cmake-commands - Man Page

Added in version 3.25.

Evaluate a group of commands with a dedicated variable and/or policy scope.

block([SCOPE_FOR [POLICIES] [VARIABLES] ] [PROPAGATE <var-name>...])
  <commands>
endblock()

All commands between block() and the matching endblock() are recorded without being invoked.  Once the endblock() is evaluated, the recorded list of commands is invoked inside the requested scopes, then the scopes created by the block() command are removed.

SCOPE_FOR

Specify which scopes must be created.

POLICIES

Create a new policy scope. This is equivalent to cmake_policy(PUSH) with an automatic cmake_policy(POP) when leaving the block scope.

VARIABLES

Create a new variable scope.

If SCOPE_FOR is not specified, this is equivalent to:

block(SCOPE_FOR VARIABLES POLICIES)

PROPAGATE

When a variable scope is created by the block() command, this option sets or unsets the specified variables in the parent scope. This is equivalent to set(PARENT_SCOPE) or unset(PARENT_SCOPE) commands.

set(var1 "INIT1")
set(var2 "INIT2")

block(PROPAGATE var1 var2)
  set(var1 "VALUE1")
  unset(var2)
endblock()

# Now var1 holds VALUE1, and var2 is unset

This option is only allowed when a variable scope is created. An error will be raised in the other cases.

When the block() is inside a foreach() or while() command, the break() and continue() commands can be used inside the block.

while(TRUE)
  block()
     ...
     # the break() command will terminate the while() command
     break()
  endblock()
endwhile()

• endblock()
• return()
• cmake_policy()

Break from an enclosing foreach or while loop.

break()

Breaks from an enclosing foreach() or while() loop.

See also the continue() command.

Query various host system information.

Query host system specific information
  cmake_host_system_information(RESULT <variable> QUERY <key> ...)

Query Windows registry
  cmake_host_system_information(RESULT <variable> QUERY WINDOWS_REGISTRY <key> ...)

cmake_host_system_information(RESULT <variable> QUERY <key> ...)

Queries system information of the host system on which cmake runs. One or more <key> can be provided to select the information to be queried.  The list of queried values is stored in <variable>.

<key> can be one of the following values:

NUMBER_OF_LOGICAL_CORES

Number of logical cores

NUMBER_OF_PHYSICAL_CORES

Number of physical cores

HOSTNAME

Hostname

FQDN

Fully qualified domain name

TOTAL_VIRTUAL_MEMORY

Total virtual memory in MiB [1]

AVAILABLE_VIRTUAL_MEMORY

Available virtual memory in MiB [1]

TOTAL_PHYSICAL_MEMORY

Total physical memory in MiB [1]

AVAILABLE_PHYSICAL_MEMORY

Available physical memory in MiB [1]

IS_64BIT

Added in version 3.10.

One if processor is 64Bit

HAS_FPU

Added in version 3.10.

One if processor has floating point unit

HAS_MMX

Added in version 3.10.

One if processor supports MMX instructions

HAS_MMX_PLUS

Added in version 3.10.

One if processor supports Ext. MMX instructions

HAS_SSE

Added in version 3.10.

One if processor supports SSE instructions

HAS_SSE2

Added in version 3.10.

One if processor supports SSE2 instructions

HAS_SSE_FP

Added in version 3.10.

One if processor supports SSE FP instructions

HAS_SSE_MMX

Added in version 3.10.

One if processor supports SSE MMX instructions

HAS_AMD_3DNOW

Added in version 3.10.

One if processor supports 3DNow instructions

HAS_AMD_3DNOW_PLUS

Added in version 3.10.

One if processor supports 3DNow+ instructions

HAS_IA64

Added in version 3.10.

One if IA64 processor emulating x86

HAS_SERIAL_NUMBER

Added in version 3.10.

One if processor has serial number

PROCESSOR_SERIAL_NUMBER

Added in version 3.10.

Processor serial number

PROCESSOR_NAME

Added in version 3.10.

Human readable processor name

PROCESSOR_DESCRIPTION

Added in version 3.10.

Human readable full processor description

OS_NAME

Added in version 3.10.

See CMAKE_HOST_SYSTEM_NAME

OS_RELEASE

Added in version 3.10.

The OS sub-type e.g. on Windows Professional

OS_VERSION

Added in version 3.10.

The OS build ID

OS_PLATFORM

Added in version 3.10.

See CMAKE_HOST_SYSTEM_PROCESSOR

MSYSTEM_PREFIX

Added in version 3.28.

Available only on Windows hosts.  In a MSYS or MinGW development environment that sets the MSYSTEM environment variable, this is its installation prefix.  Otherwise, this is the empty string.

DISTRIB_INFO

Added in version 3.22.

Read /etc/os-release file and define the given <variable> into a list of read variables

DISTRIB_<name>

Added in version 3.22.

Get the <name> variable (see man 5 os-release) if it exists in the /etc/os-release file

Example:

cmake_host_system_information(RESULT PRETTY_NAME QUERY DISTRIB_PRETTY_NAME)
message(STATUS "${PRETTY_NAME}")

cmake_host_system_information(RESULT DISTRO QUERY DISTRIB_INFO)

foreach(VAR IN LISTS DISTRO)
  message(STATUS "${VAR}=`${${VAR}}`")
endforeach()

Output:

-- Ubuntu 20.04.2 LTS
-- DISTRO_BUG_REPORT_URL=`https://bugs.launchpad.net/ubuntu/`
-- DISTRO_HOME_URL=`https://www.ubuntu.com/`
-- DISTRO_ID=`ubuntu`
-- DISTRO_ID_LIKE=`debian`
-- DISTRO_NAME=`Ubuntu`
-- DISTRO_PRETTY_NAME=`Ubuntu 20.04.2 LTS`
-- DISTRO_PRIVACY_POLICY_URL=`https://www.ubuntu.com/legal/terms-and-policies/privacy-policy`
-- DISTRO_SUPPORT_URL=`https://help.ubuntu.com/`
-- DISTRO_UBUNTU_CODENAME=`focal`
-- DISTRO_VERSION=`20.04.2 LTS (Focal Fossa)`
-- DISTRO_VERSION_CODENAME=`focal`
-- DISTRO_VERSION_ID=`20.04`

If /etc/os-release file is not found, the command tries to gather OS identification via fallback scripts.  The fallback script can use various distribution-specific files to collect OS identification data and map it into man 5 os-release variables.

CMAKE_GET_OS_RELEASE_FALLBACK_SCRIPTS

In addition to the scripts shipped with CMake, a user may append full paths to his script(s) to the this list.  The script filename has the following format: NNN-<name>.cmake, where NNN is three digits used to apply collected scripts in a specific order.

CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_<varname>

Variables collected by the user provided fallback script ought to be assigned to CMake variables using this naming convention.  Example, the ID variable from the manual becomes CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID.

CMAKE_GET_OS_RELEASE_FALLBACK_RESULT

The fallback script ought to store names of all assigned CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_<varname> variables in this list.

Example:

# Try to detect some old distribution
# See also
# - http://linuxmafia.com/faq/Admin/release-files.html
#
if(NOT EXISTS "${CMAKE_SYSROOT}/etc/foobar-release")
  return()
endif()
# Get the first string only
file(
    STRINGS "${CMAKE_SYSROOT}/etc/foobar-release" CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT
    LIMIT_COUNT 1
  )
#
# Example:
#
#   Foobar distribution release 1.2.3 (server)
#
if(CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT MATCHES "Foobar distribution release ([0-9\.]+) .*")
  set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_NAME Foobar)
  set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_PRETTY_NAME "${CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT}")
  set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID foobar)
  set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION ${CMAKE_MATCH_1})
  set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION_ID ${CMAKE_MATCH_1})
  list(
      APPEND CMAKE_GET_OS_RELEASE_FALLBACK_RESULT
      CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_NAME
      CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_PRETTY_NAME
      CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID
      CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION
      CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION_ID
    )
endif()
unset(CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT)

Added in version 3.24.

cmake_host_system_information(RESULT <variable>
                              QUERY WINDOWS_REGISTRY <key> [VALUE_NAMES|SUBKEYS|VALUE <name>]
                              [VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
                              [SEPARATOR <separator>]
                              [ERROR_VARIABLE <result>])

Performs query operations on local computer registry subkey. Returns a list of subkeys or value names that are located under the specified subkey in the registry or the data of the specified value name. The result of the queried entity is stored in <variable>.

NOTE:

<key> specify the full path of a subkey on the local computer. The <key> must include a valid root key. Valid root keys for the local computer are:

• HKLM or HKEY_LOCAL_MACHINE
• HKCU or HKEY_CURRENT_USER
• HKCR or HKEY_CLASSES_ROOT
• HKU or HKEY_USERS
• HKCC or HKEY_CURRENT_CONFIG

And, optionally, the path to a subkey under the specified root key. The path separator can be the slash or the backslash. <key> is not case sensitive. For example:

cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKLM")
cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware")
cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKCU\\SOFTWARE\\Kitware")

VALUE_NAMES

Request the list of value names defined under <key>. If a default value is defined, it will be identified with the special name (default).

SUBKEYS

Request the list of subkeys defined under <key>.

VALUE <name>

Request the data stored in value named <name>. If VALUE is not specified or argument is the special name (default), the content of the default value, if any, will be returned.

# query default value for HKLM/SOFTWARE/Kitware key
cmake_host_system_information(RESULT result
                              QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware")

# query default value for HKLM/SOFTWARE/Kitware key using special value name
cmake_host_system_information(RESULT result
                              QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware"
                              VALUE "(default)")

Supported types are:

• REG_SZ.
• REG_EXPAND_SZ. The returned data is expanded.
• REG_MULTI_SZ. The returned is expressed as a CMake list. See also SEPARATOR sub-option.
• REG_DWORD.
• REG_QWORD.

For all other types, an empty string is returned.

VIEW

Specify which registry views must be queried. When not specified, BOTH view is used.

64

Query the 64bit registry. On 32bit Windows, returns always an empty string.

32

Query the 32bit registry.

64_32

For VALUE sub-option or default value, query the registry using view 64, and if the request failed, query the registry using view 32. For VALUE_NAMES and SUBKEYS sub-options, query both views (64 and 32) and merge the results (sorted and duplicates removed).

32_64

For VALUE sub-option or default value, query the registry using view 32, and if the request failed, query the registry using view 64. For VALUE_NAMES and SUBKEYS sub-options, query both views (32 and 64) and merge the results (sorted and duplicates removed).

HOST

Query the registry matching the architecture of the host: 64 on 64bit Windows and 32 on 32bit Windows.

TARGET

Query the registry matching the architecture specified by CMAKE_SIZEOF_VOID_P variable. If not defined, fallback to HOST view.

BOTH

Query both views (32 and 64). The order depends of the following rules: If CMAKE_SIZEOF_VOID_P variable is defined. Use the following view depending of the content of this variable:

• 8: 64_32
• 4: 32_64

If CMAKE_SIZEOF_VOID_P variable is not defined, rely on architecture of the host:

• 64bit: 64_32
• 32bit: 32

SEPARATOR

Specify the separator character for REG_MULTI_SZ type. When not specified, the character \0 is used.

ERROR_VARIABLE <result>

Returns any error raised during query operation. In case of success, the variable holds an empty string.

Added in version 3.18.

Call meta-operations on CMake commands.

cmake_language(CALL <command> [<arg>...])
cmake_language(EVAL CODE <code>...)
cmake_language(DEFER <options>... CALL <command> [<arg>...])
cmake_language(SET_DEPENDENCY_PROVIDER <command> SUPPORTED_METHODS <methods>...)
cmake_language(GET_MESSAGE_LOG_LEVEL <out-var>)

This command will call meta-operations on built-in CMake commands or those created via the macro() or function() commands.

cmake_language does not introduce a new variable or policy scope.

cmake_language(CALL <command> [<arg>...])

Calls the named <command> with the given arguments (if any). For example, the code:

set(message_command "message")
cmake_language(CALL ${message_command} STATUS "Hello World!")

is equivalent to

message(STATUS "Hello World!")

NOTE:

To ensure consistency of the code, the following commands are not allowed:

• if / elseif / else / endif
• block / endblock
• while / endwhile
• foreach / endforeach
• function / endfunction
• macro / endmacro

cmake_language(EVAL CODE <code>...)

Evaluates the <code>... as CMake code.

For example, the code:

set(A TRUE)
set(B TRUE)
set(C TRUE)
set(condition "(A AND B) OR C")

cmake_language(EVAL CODE "
  if (${condition})
    message(STATUS TRUE)
  else()
    message(STATUS FALSE)
  endif()"
)

is equivalent to

set(A TRUE)
set(B TRUE)
set(C TRUE)
set(condition "(A AND B) OR C")

file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/eval.cmake "
  if (${condition})
    message(STATUS TRUE)
  else()
    message(STATUS FALSE)
  endif()"
)

include(${CMAKE_CURRENT_BINARY_DIR}/eval.cmake)

Added in version 3.19.

cmake_language(DEFER <options>... CALL <command> [<arg>...])

Schedules a call to the named <command> with the given arguments (if any) to occur at a later time.  By default, deferred calls are executed as if written at the end of the current directory's CMakeLists.txt file, except that they run even after a return() call.  Variable references in arguments are evaluated at the time the deferred call is executed.

The options are:

DIRECTORY <dir>

Schedule the call for the end of the given directory instead of the current directory.  The <dir> may reference either a source directory or its corresponding binary directory.  Relative paths are treated as relative to the current source directory.

The given directory must be known to CMake, being either the top-level directory or one added by add_subdirectory().  Furthermore, the given directory must not yet be finished processing.  This means it can be the current directory or one of its ancestors.

ID <id>

Specify an identification for the deferred call. The <id> may not be empty and may not begin with a capital letter A-Z. The <id> may begin with an underscore (_) only if it was generated automatically by an earlier call that used ID_VAR to get the id.

ID_VAR <var>

Specify a variable in which to store the identification for the deferred call.  If ID <id> is not given, a new identification will be generated and the generated id will start with an underscore (_).

The currently scheduled list of deferred calls may be retrieved:

cmake_language(DEFER [DIRECTORY <dir>] GET_CALL_IDS <var>)

This will store in <var> a semicolon-separated list of deferred call ids.  The ids are for the directory scope in which the calls have been deferred to (i.e. where they will be executed), which can be different to the scope in which they were created.  The DIRECTORY option can be used to specify the scope for which to retrieve the call ids. If that option is not given, the call ids for the current directory scope will be returned.

Details of a specific call may be retrieved from its id:

cmake_language(DEFER [DIRECTORY <dir>] GET_CALL <id> <var>)

This will store in <var> a semicolon-separated list in which the first element is the name of the command to be called, and the remaining elements are its unevaluated arguments (any contained ; characters are included literally and cannot be distinguished from multiple arguments).  If multiple calls are scheduled with the same id, this retrieves the first one.  If no call is scheduled with the given id in the specified DIRECTORY scope (or the current directory scope if no DIRECTORY option is given), this stores an empty string in the variable.

Deferred calls may be canceled by their id:

cmake_language(DEFER [DIRECTORY <dir>] CANCEL_CALL <id>...)

This cancels all deferred calls matching any of the given ids in the specified DIRECTORY scope (or the current directory scope if no DIRECTORY option is given).  Unknown ids are silently ignored.

For example, the code:

cmake_language(DEFER CALL message "${deferred_message}")
cmake_language(DEFER ID_VAR id CALL message "Canceled Message")
cmake_language(DEFER CANCEL_CALL ${id})
message("Immediate Message")
set(deferred_message "Deferred Message")

prints:

Immediate Message
Deferred Message

The Canceled Message is never printed because its command is canceled.  The deferred_message variable reference is not evaluated until the call site, so it can be set after the deferred call is scheduled.

In order to evaluate variable references immediately when scheduling a deferred call, wrap it using cmake_language(EVAL).  However, note that arguments will be re-evaluated in the deferred call, though that can be avoided by using bracket arguments.  For example:

set(deferred_message "Deferred Message 1")
set(re_evaluated [[${deferred_message}]])
cmake_language(EVAL CODE "
  cmake_language(DEFER CALL message [[${deferred_message}]])
  cmake_language(DEFER CALL message \"${re_evaluated}\")
")
message("Immediate Message")
set(deferred_message "Deferred Message 2")

also prints:

Immediate Message
Deferred Message 1
Deferred Message 2

Added in version 3.24.

NOTE:

A high-level introduction to this feature can be found in the Using Dependencies Guide.

cmake_language(SET_DEPENDENCY_PROVIDER <command> SUPPORTED_METHODS <methods>...)

When a call is made to find_package() or FetchContent_MakeAvailable(), the call may be forwarded to a dependency provider which then has the opportunity to fulfill the request. If the request is for one of the <methods> specified when the provider was set, CMake calls the provider's <command> with a set of method-specific arguments.  If the provider does not fulfill the request, or if the provider doesn't support the request's method, or no provider is set, the built-in find_package() or FetchContent_MakeAvailable() implementation is used to fulfill the request in the usual way.

One or more of the following values can be specified for the <methods> when setting the provider:

FIND_PACKAGE

The provider command accepts find_package() requests.

FETCHCONTENT_MAKEAVAILABLE_SERIAL

The provider command accepts FetchContent_MakeAvailable() requests.  It expects each dependency to be fed to the provider command one at a time, not the whole list in one go.

Only one provider can be set at any point in time.  If a provider is already set when cmake_language(SET_DEPENDENCY_PROVIDER) is called, the new provider replaces the previously set one.  The specified <command> must already exist when cmake_language(SET_DEPENDENCY_PROVIDER) is called. As a special case, providing an empty string for the <command> and no <methods> will discard any previously set provider.

The dependency provider can only be set while processing one of the files specified by the CMAKE_PROJECT_TOP_LEVEL_INCLUDES variable. Thus, dependency providers can only be set as part of the first call to project().  Calling cmake_language(SET_DEPENDENCY_PROVIDER) outside of that context will result in an error.

NOTE:

The choice of dependency provider should always be under the user's control. As a convenience, a project may choose to provide a file that users can list in their CMAKE_PROJECT_TOP_LEVEL_INCLUDES variable, but the use of such a file should always be the user's choice.

Providers define a single <command> to accept requests.  The name of the command should be specific to that provider, not something overly generic that another provider might also use.  This enables users to compose different providers in their own custom provider.  The recommended form is xxx_provide_dependency(), where xxx is the provider-specific part (e.g. vcpkg_provide_dependency(), conan_provide_dependency(), ourcompany_provide_dependency(), and so on).

xxx_provide_dependency(<method> [<method-specific-args>...])

Because some methods expect certain variables to be set in the calling scope, the provider command should typically be implemented as a macro rather than a function.  This ensures it does not introduce a new variable scope.

The arguments CMake passes to the dependency provider depend on the type of request.  The first argument is always the method, and it will only ever be one of the <methods> that was specified when setting the provider.

FIND_PACKAGE

The <method-specific-args> will be everything passed to the find_package() call that requested the dependency.  The first of these <method-specific-args> will therefore always be the name of the dependency.  Dependency names are case-sensitive for this method because find_package() treats them case-sensitively too.

If the provider command fulfills the request, it must set the same variable that find_package() expects to be set.  For a dependency named depName, the provider must set depName_FOUND to true if it fulfilled the request.  If the provider returns without setting this variable, CMake will assume the request was not fulfilled and will fall back to the built-in implementation.

If the provider needs to call the built-in find_package() implementation as part of its processing, it can do so by including the BYPASS_PROVIDER keyword as one of the arguments.

FETCHCONTENT_MAKEAVAILABE_SERIAL

The <method-specific-args> will be everything passed to the FetchContent_Declare() call that corresponds to the requested dependency, with the following exceptions:

• If SOURCE_DIR or BINARY_DIR were not part of the original declared arguments, they will be added with their default values.
• If FETCHCONTENT_TRY_FIND_PACKAGE_MODE is set to NEVER, any FIND_PACKAGE_ARGS will be omitted.
• The OVERRIDE_FIND_PACKAGE keyword is always omitted.

The first of the <method-specific-args> will always be the name of the dependency.  Dependency names are case-insensitive for this method because FetchContent also treats them case-insensitively.

If the provider fulfills the request, it should call FetchContent_SetPopulated(), passing the name of the dependency as the first argument.  The SOURCE_DIR and BINARY_DIR arguments to that command should only be given if the provider makes the dependency's source and build directories available in exactly the same way as the built-in FetchContent_MakeAvailable() command.

If the provider returns without calling FetchContent_SetPopulated() for the named dependency, CMake will assume the request was not fulfilled and will fall back to the built-in implementation.

Note that empty arguments may be significant for this method (e.g. an empty string following a GIT_SUBMODULES keyword).  Therefore, if forwarding these arguments on to another command, extra care must be taken to avoid such arguments being silently dropped.

If FETCHCONTENT_SOURCE_DIR_<uppercaseDepName> is set, then the dependency provider will never see requests for the <depName> dependency for this method. When the user sets such a variable, they are explicitly overriding where to get that dependency from and are taking on the responsibility that their overriding version meets any requirements for that dependency and is compatible with whatever else in the project uses it. Depending on the value of FETCHCONTENT_TRY_FIND_PACKAGE_MODE and whether the OVERRIDE_FIND_PACKAGE option was given to FetchContent_Declare(), having FETCHCONTENT_SOURCE_DIR_<uppercaseDepName> set may also prevent the dependency provider from seeing requests for a find_package(depName) call too.

This first example only intercepts find_package() calls.  The provider command runs an external tool which copies the relevant artifacts into a provider-specific directory, if that tool knows about the dependency. It then relies on the built-in implementation to then find those artifacts. FetchContent_MakeAvailable() calls would not go through the provider.

mycomp_provider.cmake

# Always ensure we have the policy settings this provider expects
cmake_minimum_required(VERSION 3.24)

set(MYCOMP_PROVIDER_INSTALL_DIR ${CMAKE_BINARY_DIR}/mycomp_packages
  CACHE PATH "The directory this provider installs packages to"
)
# Tell the built-in implementation to look in our area first, unless
# the find_package() call uses NO_..._PATH options to exclude it
list(APPEND CMAKE_MODULE_PATH ${MYCOMP_PROVIDER_INSTALL_DIR}/cmake)
list(APPEND CMAKE_PREFIX_PATH ${MYCOMP_PROVIDER_INSTALL_DIR})

macro(mycomp_provide_dependency method package_name)
  execute_process(
    COMMAND some_tool ${package_name} --installdir ${MYCOMP_PROVIDER_INSTALL_DIR}
    COMMAND_ERROR_IS_FATAL ANY
  )
endmacro()

cmake_language(
  SET_DEPENDENCY_PROVIDER mycomp_provide_dependency
  SUPPORTED_METHODS FIND_PACKAGE
)

The user would then typically use the above file like so:

cmake -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=/path/to/mycomp_provider.cmake ...

The next example demonstrates a provider that accepts both methods, but only handles one specific dependency.  It enforces providing Google Test using FetchContent, but leaves all other dependencies to be fulfilled by CMake's built-in implementation.  It accepts a few different names, which demonstrates one way of working around projects that hard-code an unusual or undesirable way of adding this particular dependency to the build.  The example also demonstrates how to use the list() command to preserve variables that may be overwritten by a call to FetchContent_MakeAvailable().

mycomp_provider.cmake

cmake_minimum_required(VERSION 3.24)

# Because we declare this very early, it will take precedence over any
# details the project might declare later for the same thing
include(FetchContent)
FetchContent_Declare(
  googletest
  GIT_REPOSITORY https://github.com/google/googletest.git
  GIT_TAG        e2239ee6043f73722e7aa812a459f54a28552929 # release-1.11.0
)

# Both FIND_PACKAGE and FETCHCONTENT_MAKEAVAILABLE_SERIAL methods provide
# the package or dependency name as the first method-specific argument.
macro(mycomp_provide_dependency method dep_name)
  if("${dep_name}" MATCHES "^(gtest|googletest)$")
    # Save our current command arguments in case we are called recursively
    list(APPEND mycomp_provider_args ${method} ${dep_name})

    # This will forward to the built-in FetchContent implementation,
    # which detects a recursive call for the same thing and avoids calling
    # the provider again if dep_name is the same as the current call.
    FetchContent_MakeAvailable(googletest)

    # Restore our command arguments
    list(POP_BACK mycomp_provider_args dep_name method)

    # Tell the caller we fulfilled the request
    if("${method}" STREQUAL "FIND_PACKAGE")
      # We need to set this if we got here from a find_package() call
      # since we used a different method to fulfill the request.
      # This example assumes projects only use the gtest targets,
      # not any of the variables the FindGTest module may define.
      set(${dep_name}_FOUND TRUE)
    elseif(NOT "${dep_name}" STREQUAL "googletest")
      # We used the same method, but were given a different name to the
      # one we populated with. Tell the caller about the name it used.
      FetchContent_SetPopulated(${dep_name}
        SOURCE_DIR "${googletest_SOURCE_DIR}"
        BINARY_DIR "${googletest_BINARY_DIR}"
      )
    endif()
  endif()
endmacro()

cmake_language(
  SET_DEPENDENCY_PROVIDER mycomp_provide_dependency
  SUPPORTED_METHODS
    FIND_PACKAGE
    FETCHCONTENT_MAKEAVAILABLE_SERIAL
)

The final example demonstrates how to modify arguments to a find_package() call.  It forces all such calls to have the QUIET keyword.  It uses the BYPASS_PROVIDER keyword to prevent calling the provider command recursively for the same dependency.

mycomp_provider.cmake

cmake_minimum_required(VERSION 3.24)

macro(mycomp_provide_dependency method)
  find_package(${ARGN} BYPASS_PROVIDER QUIET)
endmacro()

cmake_language(
  SET_DEPENDENCY_PROVIDER mycomp_provide_dependency
  SUPPORTED_METHODS FIND_PACKAGE
)

Added in version 3.25.

cmake_language(GET_MESSAGE_LOG_LEVEL <output_variable>)

Writes the current message() logging level into the given <output_variable>.

See message() for the possible logging levels.

The current message logging level can be set either using the --log-level command line option of the cmake(1) program or using the CMAKE_MESSAGE_LOG_LEVEL variable.

If both the command line option and the variable are set, the command line option takes precedence. If neither are set, the default logging level is returned.

Require a minimum version of cmake.

cmake_minimum_required(VERSION <min>[...<policy_max>] [FATAL_ERROR])

Added in version 3.12: The optional <policy_max> version.

Sets the minimum required version of cmake for a project. Also updates the policy settings as explained below.

<min> and the optional <policy_max> are each CMake versions of the form major.minor[.patch[.tweak]], and the ... is literal.

If the running version of CMake is lower than the <min> required version it will stop processing the project and report an error. The optional <policy_max> version, if specified, must be at least the <min> version and affects policy settings as described in Policy Settings. If the running version of CMake is older than 3.12, the extra ... dots will be seen as version component separators, resulting in the ...<max> part being ignored and preserving the pre-3.12 behavior of basing policies on <min>.

This command will set the value of the CMAKE_MINIMUM_REQUIRED_VERSION variable to <min>.

The FATAL_ERROR option is accepted but ignored by CMake 2.6 and higher.  It should be specified so CMake versions 2.4 and lower fail with an error instead of just a warning.

NOTE:

The cmake_minimum_required(VERSION) command implicitly invokes the cmake_policy(VERSION) command to specify that the current project code is written for the given range of CMake versions. All policies known to the running version of CMake and introduced in the <min> (or <max>, if specified) version or earlier will be set to use NEW behavior.  All policies introduced in later versions will be unset.  This effectively requests behavior preferred as of a given CMake version and tells newer CMake versions to warn about their new policies.

When a <min> version higher than 2.4 is specified the command implicitly invokes

cmake_policy(VERSION <min>[...<max>])

which sets CMake policies based on the range of versions specified. When a <min> version 2.4 or lower is given the command implicitly invokes

cmake_policy(VERSION 2.4[...<max>])

which enables compatibility features for CMake 2.4 and lower.

Changed in version 3.27: Compatibility with versions of CMake older than 3.5 is deprecated. Calls to cmake_minimum_required(VERSION) or cmake_policy(VERSION) that do not specify at least 3.5 as their policy version (optionally via ...<max>) will produce a deprecation warning in CMake 3.27 and above.

Changed in version 3.19: Compatibility with versions of CMake older than 2.8.12 is deprecated. Calls to cmake_minimum_required(VERSION) or cmake_policy(VERSION) that do not specify at least 2.8.12 as their policy version (optionally via ...<max>) will produce a deprecation warning in CMake 3.19 and above.

• cmake_policy()

Parse function or macro arguments.

cmake_parse_arguments(<prefix> <options> <one_value_keywords>
                      <multi_value_keywords> <args>...)

cmake_parse_arguments(PARSE_ARGV <N> <prefix> <options>
                      <one_value_keywords> <multi_value_keywords>)

Added in version 3.5: This command is implemented natively.  Previously, it has been defined in the module CMakeParseArguments.

This command is for use in macros or functions. It processes the arguments given to that macro or function, and defines a set of variables which hold the values of the respective options.

The first signature reads processes arguments passed in the <args>.... This may be used in either a macro() or a function().

Added in version 3.7: The PARSE_ARGV signature is only for use in a function() body.  In this case the arguments that are parsed come from the ARGV# variables of the calling function.  The parsing starts with the <N>-th argument, where <N> is an unsigned integer. This allows for the values to have special characters like ; in them.

The <options> argument contains all options for the respective macro, i.e.  keywords which can be used when calling the macro without any value following, like e.g.  the OPTIONAL keyword of the install() command.

The <one_value_keywords> argument contains all keywords for this macro which are followed by one value, like e.g. DESTINATION keyword of the install() command.

The <multi_value_keywords> argument contains all keywords for this macro which can be followed by more than one value, like e.g. the TARGETS or FILES keywords of the install() command.

Changed in version 3.5: All keywords shall be unique. I.e. every keyword shall only be specified once in either <options>, <one_value_keywords> or <multi_value_keywords>. A warning will be emitted if uniqueness is violated.

When done, cmake_parse_arguments will consider for each of the keywords listed in <options>, <one_value_keywords> and <multi_value_keywords> a variable composed of the given <prefix> followed by "_" and the name of the respective keyword.  These variables will then hold the respective value from the argument list or be undefined if the associated option could not be found. For the <options> keywords, these will always be defined, to TRUE or FALSE, whether the option is in the argument list or not.

All remaining arguments are collected in a variable <prefix>_UNPARSED_ARGUMENTS that will be undefined if all arguments were recognized. This can be checked afterwards to see whether your macro was called with unrecognized parameters.

Added in version 3.15: <one_value_keywords> and <multi_value_keywords> that were given no values at all are collected in a variable <prefix>_KEYWORDS_MISSING_VALUES that will be undefined if all keywords received values. This can be checked to see if there were keywords without any values given.

Consider the following example macro, my_install(), which takes similar arguments to the real install() command:

macro(my_install)
    set(options OPTIONAL FAST)
    set(oneValueArgs DESTINATION RENAME)
    set(multiValueArgs TARGETS CONFIGURATIONS)
    cmake_parse_arguments(MY_INSTALL "${options}" "${oneValueArgs}"
                          "${multiValueArgs}" ${ARGN} )

    # ...

Assume my_install() has been called like this:

my_install(TARGETS foo bar DESTINATION bin OPTIONAL blub CONFIGURATIONS)

After the cmake_parse_arguments call the macro will have set or undefined the following variables:

MY_INSTALL_OPTIONAL = TRUE
MY_INSTALL_FAST = FALSE # was not used in call to my_install
MY_INSTALL_DESTINATION = "bin"
MY_INSTALL_RENAME <UNDEFINED> # was not used
MY_INSTALL_TARGETS = "foo;bar"
MY_INSTALL_CONFIGURATIONS <UNDEFINED> # was not used
MY_INSTALL_UNPARSED_ARGUMENTS = "blub" # nothing expected after "OPTIONAL"
MY_INSTALL_KEYWORDS_MISSING_VALUES = "CONFIGURATIONS"
         # No value for "CONFIGURATIONS" given

You can then continue and process these variables.

Keywords terminate lists of values, e.g. if directly after a one_value_keyword another recognized keyword follows, this is interpreted as the beginning of the new option.  E.g. my_install(TARGETS foo DESTINATION OPTIONAL) would result in MY_INSTALL_DESTINATION set to "OPTIONAL", but as OPTIONAL is a keyword itself MY_INSTALL_DESTINATION will be empty (but added to MY_INSTALL_KEYWORDS_MISSING_VALUES) and MY_INSTALL_OPTIONAL will therefore be set to TRUE.

• function()
• macro()

Added in version 3.20.

This command is for the manipulation of paths.  Only syntactic aspects of paths are handled, there is no interaction of any kind with any underlying file system.  The path may represent a non-existing path or even one that is not allowed to exist on the current file system or platform. For operations that do interact with the filesystem, see the file() command.

NOTE:

Conventions

Path Structure And Terminology

Normalization

Decomposition
  cmake_path(GET <path-var> ROOT_NAME <out-var>)
  cmake_path(GET <path-var> ROOT_DIRECTORY <out-var>)
  cmake_path(GET <path-var> ROOT_PATH <out-var>)
  cmake_path(GET <path-var> FILENAME <out-var>)
  cmake_path(GET <path-var> EXTENSION [LAST_ONLY] <out-var>)
  cmake_path(GET <path-var> STEM [LAST_ONLY] <out-var>)
  cmake_path(GET <path-var> RELATIVE_PART <out-var>)
  cmake_path(GET <path-var> PARENT_PATH <out-var>)

Query
  cmake_path(HAS_ROOT_NAME <path-var> <out-var>)
  cmake_path(HAS_ROOT_DIRECTORY <path-var> <out-var>)
  cmake_path(HAS_ROOT_PATH <path-var> <out-var>)
  cmake_path(HAS_FILENAME <path-var> <out-var>)
  cmake_path(HAS_EXTENSION <path-var> <out-var>)
  cmake_path(HAS_STEM <path-var> <out-var>)
  cmake_path(HAS_RELATIVE_PART <path-var> <out-var>)
  cmake_path(HAS_PARENT_PATH <path-var> <out-var>)
  cmake_path(IS_ABSOLUTE <path-var> <out-var>)
  cmake_path(IS_RELATIVE <path-var> <out-var>)
  cmake_path(IS_PREFIX <path-var> <input> [NORMALIZE] <out-var>)
  cmake_path(COMPARE <input1> <OP> <input2> <out-var>)

Modification
  cmake_path(SET <path-var> [NORMALIZE] <input>)
  cmake_path(APPEND <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])
  cmake_path(APPEND_STRING <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])
  cmake_path(REMOVE_FILENAME <path-var> [OUTPUT_VARIABLE <out-var>])
  cmake_path(REPLACE_FILENAME <path-var> <input> [OUTPUT_VARIABLE <out-var>])
  cmake_path(REMOVE_EXTENSION <path-var> [LAST_ONLY] [OUTPUT_VARIABLE <out-var>])
  cmake_path(REPLACE_EXTENSION <path-var> [LAST_ONLY] <input> [OUTPUT_VARIABLE <out-var>])

Generation
  cmake_path(NORMAL_PATH <path-var> [OUTPUT_VARIABLE <out-var>])
  cmake_path(RELATIVE_PATH <path-var> [BASE_DIRECTORY <input>] [OUTPUT_VARIABLE <out-var>])
  cmake_path(ABSOLUTE_PATH <path-var> [BASE_DIRECTORY <input>] [NORMALIZE] [OUTPUT_VARIABLE <out-var>])

Native Conversion
  cmake_path(NATIVE_PATH <path-var> [NORMALIZE] <out-var>)
  cmake_path(CONVERT <input> TO_CMAKE_PATH_LIST <out-var> [NORMALIZE])
  cmake_path(CONVERT <input> TO_NATIVE_PATH_LIST <out-var> [NORMALIZE])

Hashing
  cmake_path(HASH <path-var> <out-var>)

The following conventions are used in this command's documentation:

<path-var>

Always the name of a variable.  For commands that expect a <path-var> as input, the variable must exist and it is expected to hold a single path.

<input>

A string literal which may contain a path, path fragment, or multiple paths with a special separator depending on the command.  See the description of each command to see how this is interpreted.

<input>...

Zero or more string literal arguments.

<out-var>

The name of a variable into which the result of a command will be written.

A path has the following structure (all components are optional, with some constraints):

root-name root-directory-separator (item-name directory-separator)* filename

root-name

Identifies the root on a filesystem with multiple roots (such as "C:" or "//myserver"). It is optional.

root-directory-separator

A directory separator that, if present, indicates that this path is absolute.  If it is missing and the first element other than the root-name is an item-name, then the path is relative.

item-name

A sequence of characters that aren't directory separators.  This name may identify a file, a hard link, a symbolic link, or a directory.  Two special cases are recognized:

• The item name consisting of a single dot character . is a directory name that refers to the current directory.
• The item name consisting of two dot characters .. is a directory name that refers to the parent directory.

The (...)* pattern shown above is to indicate that there can be zero or more item names, with multiple items separated by a directory-separator.  The ()* characters are not part of the path.

directory-separator

The only recognized directory separator is a forward slash character /. If this character is repeated, it is treated as a single directory separator.  In other words, /usr///////lib is the same as /usr/lib.

filename

A path has a filename if it does not end with a directory-separator. The filename is effectively the last item-name of the path, so it can also be a hard link, symbolic link or a directory.

A filename can have an extension.  By default, the extension is defined as the sub-string beginning at the left-most period (including the period) and until the end of the filename.  In commands that accept a LAST_ONLY keyword, LAST_ONLY changes the interpretation to the sub-string beginning at the right-most period.

The following exceptions apply to the above interpretation:

• If the first character in the filename is a period, that period is ignored (i.e. a filename like ".profile" is treated as having no extension).
• If the filename is either . or .., it has no extension.

The stem is the part of the filename before the extension.

Some commands refer to a root-path.  This is the concatenation of root-name and root-directory-separator, either or both of which can be empty.  A relative-part refers to the full path with any root-path removed.

While a path can be created with care using an ordinary set() command, it is recommended to use cmake_path(SET) instead, as it automatically converts the path to the required form where required.  The cmake_path(APPEND) subcommand may be another suitable alternative where a path needs to be constructed by joining fragments.  The following example compares the three methods for constructing the same path:

set(path1 "${CMAKE_CURRENT_SOURCE_DIR}/data")

cmake_path(SET path2 "${CMAKE_CURRENT_SOURCE_DIR}/data")

cmake_path(APPEND path3 "${CMAKE_CURRENT_SOURCE_DIR}" "data")

Modification and Generation sub-commands can either store the result in-place, or in a separate variable named after an OUTPUT_VARIABLE keyword.  All other sub-commands store the result in a mandatory <out-var> variable.

Some sub-commands support normalizing a path.  The algorithm used to normalize a path is as follows:

1. If the path is empty, stop (the normalized form of an empty path is also an empty path).
2. Replace each directory-separator, which may consist of multiple separators, with a single / (/a///b  --> /a/b).
3. Remove each solitary period (.) and any immediately following directory-separator (/a/./b/. --> /a/b).
4. Remove each item-name (other than ..) that is immediately followed by a directory-separator and a .., along with any immediately following directory-separator (/a/b/../c --> a/c).
5. If there is a root-directory, remove any .. and any directory-separators immediately following them.  The parent of the root directory is treated as still the root directory (/../a --> /a).
6. If the last item-name is .., remove any trailing directory-separator (../ --> ..).
7. If the path is empty by this stage, add a dot (normal form of ./ is .).

The following forms of the GET subcommand each retrieve a different component or group of components from a path.  See Path Structure And Terminology for the meaning of each path component.

cmake_path(GET <path-var> ROOT_NAME <out-var>)
cmake_path(GET <path-var> ROOT_DIRECTORY <out-var>)
cmake_path(GET <path-var> ROOT_PATH <out-var>)
cmake_path(GET <path-var> FILENAME <out-var>)
cmake_path(GET <path-var> EXTENSION [LAST_ONLY] <out-var>)
cmake_path(GET <path-var> STEM [LAST_ONLY] <out-var>)
cmake_path(GET <path-var> RELATIVE_PART <out-var>)
cmake_path(GET <path-var> PARENT_PATH <out-var>)

If a requested component is not present in the path, an empty string will be stored in <out-var>.  For example, only Windows systems have the concept of a root-name, so when the host machine is non-Windows, the ROOT_NAME subcommand will always return an empty string.

For PARENT_PATH, if the HAS_RELATIVE_PART subcommand returns false, the result is a copy of <path-var>.  Note that this implies that a root directory is considered to have a parent, with that parent being itself. Where HAS_RELATIVE_PART returns true, the result will essentially be <path-var> with one less element.

set(path "c:/a")

cmake_path(GET path ROOT_NAME rootName)
cmake_path(GET path ROOT_DIRECTORY rootDir)
cmake_path(GET path ROOT_PATH rootPath)

message("Root name is \"${rootName}\"")
message("Root directory is \"${rootDir}\"")
message("Root path is \"${rootPath}\"")

Root name is "c:"
Root directory is "/"
Root path is "c:/"

set(path "/a/b")
cmake_path(GET path FILENAME filename)
message("First filename is \"${filename}\"")

# Trailing slash means filename is empty
set(path "/a/b/")
cmake_path(GET path FILENAME filename)
message("Second filename is \"${filename}\"")

First filename is "b"
Second filename is ""

set(path "name.ext1.ext2")

cmake_path(GET path EXTENSION fullExt)
cmake_path(GET path STEM fullStem)
message("Full extension is \"${fullExt}\"")
message("Full stem is \"${fullStem}\"")

# Effect of LAST_ONLY
cmake_path(GET path EXTENSION LAST_ONLY lastExt)
cmake_path(GET path STEM LAST_ONLY lastStem)
message("Last extension is \"${lastExt}\"")
message("Last stem is \"${lastStem}\"")

# Special cases
set(dotPath "/a/.")
set(dotDotPath "/a/..")
set(someMorePath "/a/.some.more")
cmake_path(GET dotPath EXTENSION dotExt)
cmake_path(GET dotPath STEM dotStem)
cmake_path(GET dotDotPath EXTENSION dotDotExt)
cmake_path(GET dotDotPath STEM dotDotStem)
cmake_path(GET dotMorePath EXTENSION someMoreExt)
cmake_path(GET dotMorePath STEM someMoreStem)
message("Dot extension is \"${dotExt}\"")
message("Dot stem is \"${dotStem}\"")
message("Dot-dot extension is \"${dotDotExt}\"")
message("Dot-dot stem is \"${dotDotStem}\"")
message(".some.more extension is \"${someMoreExt}\"")
message(".some.more stem is \"${someMoreStem}\"")

Full extension is ".ext1.ext2"
Full stem is "name"
Last extension is ".ext2"
Last stem is "name.ext1"
Dot extension is ""
Dot stem is "."
Dot-dot extension is ""
Dot-dot stem is ".."
.some.more extension is ".more"
.some.more stem is ".some"

set(path "c:/a/b")
cmake_path(GET path RELATIVE_PART result)
message("Relative part is \"${result}\"")

set(path "c/d")
cmake_path(GET path RELATIVE_PART result)
message("Relative part is \"${result}\"")

set(path "/")
cmake_path(GET path RELATIVE_PART result)
message("Relative part is \"${result}\"")

Relative part is "a/b"
Relative part is "c/d"
Relative part is ""

set(path "c:/a/b")
cmake_path(GET path PARENT_PATH result)
message("Parent path is \"${result}\"")

set(path "c:/")
cmake_path(GET path PARENT_PATH result)
message("Parent path is \"${result}\"")

Parent path is "c:/a"
Parent path is "c:/"

Each of the GET subcommands has a corresponding HAS_... subcommand which can be used to discover whether a particular path component is present.  See Path Structure And Terminology for the meaning of each path component.

cmake_path(HAS_ROOT_NAME <path-var> <out-var>)
cmake_path(HAS_ROOT_DIRECTORY <path-var> <out-var>)
cmake_path(HAS_ROOT_PATH <path-var> <out-var>)
cmake_path(HAS_FILENAME <path-var> <out-var>)
cmake_path(HAS_EXTENSION <path-var> <out-var>)
cmake_path(HAS_STEM <path-var> <out-var>)
cmake_path(HAS_RELATIVE_PART <path-var> <out-var>)
cmake_path(HAS_PARENT_PATH <path-var> <out-var>)

Each of the above follows the predictable pattern of setting <out-var> to true if the path has the associated component, or false otherwise. Note the following special cases:

• For HAS_ROOT_PATH, a true result will only be returned if at least one of root-name or root-directory is non-empty.

• For HAS_PARENT_PATH, the root directory is also considered to have a parent, which will be itself.  The result is true except if the path consists of just a filename.

  cmake_path(IS_ABSOLUTE <path-var> <out-var>)

Sets <out-var> to true if <path-var> is absolute.  An absolute path is a path that unambiguously identifies the location of a file without reference to an additional starting location.  On Windows, this means the path must have both a root-name and a root-directory-separator to be considered absolute.  On other platforms, just a root-directory-separator is sufficient.  Note that this means on Windows, IS_ABSOLUTE can be false while HAS_ROOT_DIRECTORY can be true.

cmake_path(IS_RELATIVE <path-var> <out-var>)

This will store the opposite of IS_ABSOLUTE in <out-var>.

cmake_path(IS_PREFIX <path-var> <input> [NORMALIZE] <out-var>)

Checks if <path-var> is the prefix of <input>.

When the NORMALIZE option is specified, <path-var> and <input> are normalized before the check.

set(path "/a/b/c")
cmake_path(IS_PREFIX path "/a/b/c/d" result) # result = true
cmake_path(IS_PREFIX path "/a/b" result)     # result = false
cmake_path(IS_PREFIX path "/x/y/z" result)   # result = false

set(path "/a/b")
cmake_path(IS_PREFIX path "/a/c/../b" NORMALIZE result)   # result = true

cmake_path(COMPARE <input1> EQUAL <input2> <out-var>)
cmake_path(COMPARE <input1> NOT_EQUAL <input2> <out-var>)

Compares the lexical representations of two paths provided as string literals. No normalization is performed on either path, except multiple consecutive directory separators are effectively collapsed into a single separator. Equality is determined according to the following pseudo-code logic:

if(NOT <input1>.root_name() STREQUAL <input2>.root_name())
  return FALSE

if(<input1>.has_root_directory() XOR <input2>.has_root_directory())
  return FALSE

Return FALSE if a relative portion of <input1> is not lexicographically
equal to the relative portion of <input2>. This comparison is performed path
component-wise. If all of the components compare equal, then return TRUE.

NOTE:

Unlike most other cmake_path() subcommands, the COMPARE subcommand takes literal strings as input, not the names of variables.

cmake_path(SET <path-var> [NORMALIZE] <input>)

Assign the <input> path to <path-var>.  If <input> is a native path, it is converted into a cmake-style path with forward-slashes (/). On Windows, the long filename marker is taken into account.

When the NORMALIZE option is specified, the path is normalized after the conversion.

For example:

set(native_path "c:\\a\\b/..\\c")
cmake_path(SET path "${native_path}")
message("CMake path is \"${path}\"")

cmake_path(SET path NORMALIZE "${native_path}")
message("Normalized CMake path is \"${path}\"")

Output:

CMake path is "c:/a/b/../c"
Normalized CMake path is "c:/a/c"

cmake_path(APPEND <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])

Append all the <input> arguments to the <path-var> using / as the directory-separator.  Depending on the <input>, the previous contents of <path-var> may be discarded.  For each <input> argument, the following algorithm (pseudo-code) applies:

# <path> is the contents of <path-var>

if(<input>.is_absolute() OR
   (<input>.has_root_name() AND
    NOT <input>.root_name() STREQUAL <path>.root_name()))
  replace <path> with <input>
  return()
endif()

if(<input>.has_root_directory())
  remove any root-directory and the entire relative path from <path>
elseif(<path>.has_filename() OR
       (NOT <path-var>.has_root_directory() OR <path>.is_absolute()))
  append directory-separator to <path>
endif()

append <input> omitting any root-name to <path>

cmake_path(APPEND_STRING <path-var> [<input>...] [OUTPUT_VARIABLE <out-var>])

Append all the <input> arguments to the <path-var> without adding any directory-separator.

cmake_path(REMOVE_FILENAME <path-var> [OUTPUT_VARIABLE <out-var>])

Removes the filename component (as returned by GET ... FILENAME) from <path-var>.  After removal, any trailing directory-separator is left alone, if present.

If OUTPUT_VARIABLE is not given, then after this function returns, HAS_FILENAME returns false for <path-var>.

For example:

set(path "/a/b")
cmake_path(REMOVE_FILENAME path)
message("First path is \"${path}\"")

# filename is now already empty, the following removes nothing
cmake_path(REMOVE_FILENAME path)
message("Second path is \"${result}\"")

Output:

First path is "/a/"
Second path is "/a/"

cmake_path(REPLACE_FILENAME <path-var> <input> [OUTPUT_VARIABLE <out-var>])

Replaces the filename component from <path-var> with <input>.  If <path-var> has no filename component (i.e. HAS_FILENAME returns false), the path is unchanged.  The operation is equivalent to the following:

cmake_path(HAS_FILENAME path has_filename)
if(has_filename)
  cmake_path(REMOVE_FILENAME path)
  cmake_path(APPEND path input);
endif()

cmake_path(REMOVE_EXTENSION <path-var> [LAST_ONLY]
                                       [OUTPUT_VARIABLE <out-var>])

Removes the extension, if any, from <path-var>.

cmake_path(REPLACE_EXTENSION <path-var> [LAST_ONLY] <input>
                             [OUTPUT_VARIABLE <out-var>])

Replaces the extension with <input>.  Its effect is equivalent to the following:

cmake_path(REMOVE_EXTENSION path)
if(NOT "input" MATCHES "^\\.")
  cmake_path(APPEND_STRING path ".")
endif()
cmake_path(APPEND_STRING path "input")

cmake_path(NORMAL_PATH <path-var> [OUTPUT_VARIABLE <out-var>])

Normalize <path-var> according the steps described in Normalization.

cmake_path(RELATIVE_PATH <path-var> [BASE_DIRECTORY <input>]
                                    [OUTPUT_VARIABLE <out-var>])

Modifies <path-var> to make it relative to the BASE_DIRECTORY argument. If BASE_DIRECTORY is not specified, the default base directory will be CMAKE_CURRENT_SOURCE_DIR.

For reference, the algorithm used to compute the relative path is the same as that used by C++ std::filesystem::path::lexically_relative.

cmake_path(ABSOLUTE_PATH <path-var> [BASE_DIRECTORY <input>] [NORMALIZE]
                                    [OUTPUT_VARIABLE <out-var>])

If <path-var> is a relative path (IS_RELATIVE is true), it is evaluated relative to the given base directory specified by BASE_DIRECTORY option. If BASE_DIRECTORY is not specified, the default base directory will be CMAKE_CURRENT_SOURCE_DIR.

When the NORMALIZE option is specified, the path is normalized after the path computation.

Because cmake_path() does not access the filesystem, symbolic links are not resolved and any leading tilde is not expanded.  To compute a real path with symbolic links resolved and leading tildes expanded, use the file(REAL_PATH) command instead.

For commands in this section, native refers to the host platform, not the target platform when cross-compiling.

cmake_path(NATIVE_PATH <path-var> [NORMALIZE] <out-var>)

Converts a cmake-style <path-var> into a native path with platform-specific slashes (\ on Windows hosts and / elsewhere).

When the NORMALIZE option is specified, the path is normalized before the conversion.

cmake_path(CONVERT <input> TO_CMAKE_PATH_LIST <out-var> [NORMALIZE])

Converts a native <input> path into a cmake-style path with forward slashes (/).  On Windows hosts, the long filename marker is taken into account.  The input can be a single path or a system search path like $ENV{PATH}.  A search path will be converted to a cmake-style list separated by ; characters (on non-Windows platforms, this essentially means : separators are replaced with ;).  The result of the conversion is stored in the <out-var> variable.

When the NORMALIZE option is specified, the path is normalized before the conversion.

NOTE:

cmake_path(CONVERT <input> TO_NATIVE_PATH_LIST <out-var> [NORMALIZE])

Converts a cmake-style <input> path into a native path with platform-specific slashes (\ on Windows hosts and / elsewhere). The input can be a single path or a cmake-style list.  A list will be converted into a native search path (;-separated on Windows, :-separated on other platforms).  The result of the conversion is stored in the <out-var> variable.

When the NORMALIZE option is specified, the path is normalized before the conversion.

NOTE:

For example:

set(paths "/a/b/c" "/x/y/z")
cmake_path(CONVERT "${paths}" TO_NATIVE_PATH_LIST native_paths)
message("Native path list is \"${native_paths}\"")

Output on Windows:

Native path list is "\a\b\c;\x\y\z"

Output on all other platforms:

Native path list is "/a/b/c:/x/y/z"

cmake_path(HASH <path-var> <out-var>)

Compute a hash value of <path-var> such that for two paths p1 and p2 that compare equal (COMPARE ... EQUAL), the hash value of p1 is equal to the hash value of p2.  The path is always normalized before the hash is computed.

Manage CMake Policy settings.  See the cmake-policies(7) manual for defined policies.

As CMake evolves it is sometimes necessary to change existing behavior in order to fix bugs or improve implementations of existing features. The CMake Policy mechanism is designed to help keep existing projects building as new versions of CMake introduce changes in behavior.  Each new policy (behavioral change) is given an identifier of the form CMP<NNNN> where <NNNN> is an integer index.  Documentation associated with each policy describes the OLD and NEW behavior and the reason the policy was introduced.  Projects may set each policy to select the desired behavior.  When CMake needs to know which behavior to use it checks for a setting specified by the project.  If no setting is available the OLD behavior is assumed and a warning is produced requesting that the policy be set.

The cmake_policy command is used to set policies to OLD or NEW behavior.  While setting policies individually is supported, we encourage projects to set policies based on CMake versions:

cmake_policy(VERSION <min>[...<max>])

Added in version 3.12: The optional <max> version.

<min> and the optional <max> are each CMake versions of the form major.minor[.patch[.tweak]], and the ... is literal.  The <min> version must be at least 2.4 and at most the running version of CMake. The <max> version, if specified, must be at least the <min> version but may exceed the running version of CMake.  If the running version of CMake is older than 3.12, the extra ... dots will be seen as version component separators, resulting in the ...<max> part being ignored and preserving the pre-3.12 behavior of basing policies on <min>.

This specifies that the current CMake code is written for the given range of CMake versions.  All policies known to the running version of CMake and introduced in the <min> (or <max>, if specified) version or earlier will be set to use NEW behavior.  All policies introduced in later versions will be unset (unless the CMAKE_POLICY_DEFAULT_CMP<NNNN> variable sets a default). This effectively requests behavior preferred as of a given CMake version and tells newer CMake versions to warn about their new policies.

Note that the cmake_minimum_required(VERSION) command implicitly calls cmake_policy(VERSION) too.

Changed in version 3.27: Compatibility with versions of CMake older than 3.5 is deprecated. Calls to cmake_minimum_required(VERSION) or cmake_policy(VERSION) that do not specify at least 3.5 as their policy version (optionally via ...<max>) will produce a deprecation warning in CMake 3.27 and above.

Changed in version 3.19: Compatibility with versions of CMake older than 2.8.12 is deprecated. Calls to cmake_minimum_required(VERSION) or cmake_policy(VERSION) that do not specify at least 2.8.12 as their policy version (optionally via ...<max>) will produce a deprecation warning in CMake 3.19 and above.

cmake_policy(SET CMP<NNNN> NEW|OLD)

Tell CMake to use the OLD or NEW behavior for a given policy. Projects depending on the old behavior of a given policy may silence a policy warning by setting the policy state to OLD.  Alternatively one may fix the project to work with the new behavior and set the policy state to NEW.

NOTE:

cmake_policy(GET CMP<NNNN> <variable>)

Check whether a given policy is set to OLD or NEW behavior. The output <variable> value will be OLD or NEW if the policy is set, and empty otherwise.

CMake keeps policy settings on a stack, so changes made by the cmake_policy command affect only the top of the stack.  A new entry on the policy stack is managed automatically for each subdirectory to protect its parents and siblings.  CMake also manages a new entry for scripts loaded by include() and find_package() commands except when invoked with the NO_POLICY_SCOPE option (see also policy CMP0011). The cmake_policy command provides an interface to manage custom entries on the policy stack:

cmake_policy(PUSH)

Create a new entry on the policy stack.

cmake_policy(POP)

Remove the last policy stack entry created with cmake_policy(PUSH).

Each PUSH must have a matching POP to erase any changes. This is useful to make temporary changes to policy settings. Calls to the cmake_minimum_required(VERSION), cmake_policy(VERSION), or cmake_policy(SET) commands influence only the current top of the policy stack.

Added in version 3.25: The block(SCOPE_FOR POLICIES) command offers a more flexible and more secure way to manage the policy stack. The pop action is done automatically when leaving the block scope, so there is no need to precede each return() with a call to cmake_policy(POP).

# stack management with cmake_policy()
function(my_func)
  cmake_policy(PUSH)
  cmake_policy(SET ...)
  if (<cond1>)
    ...
    cmake_policy(POP)
    return()
  elseif(<cond2>)
    ...
    cmake_policy(POP)
    return()
  endif()
  ...
  cmake_policy(POP)
endfunction()

# stack management with block()/endblock()
function(my_func)
  block(SCOPE_FOR POLICIES)
    cmake_policy(SET ...)
    if (<cond1>)
      ...
      return()
    elseif(<cond2>)
      ...
      return()
    endif()
    ...
  endblock()
endfunction()

Commands created by the function() and macro() commands record policy settings when they are created and use the pre-record policies when they are invoked.  If the function or macro implementation sets policies, the changes automatically propagate up through callers until they reach the closest nested policy stack entry.

• cmake_minimum_required()

Copy a file to another location and modify its contents.

configure_file(<input> <output>
               [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS |
                FILE_PERMISSIONS <permissions>...]
               [COPYONLY] [ESCAPE_QUOTES] [@ONLY]
               [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])

Copies an <input> file to an <output> file and substitutes variable values referenced as @VAR@, ${VAR}, $CACHE{VAR} or $ENV{VAR} in the input file content.  Each variable reference will be replaced with the current value of the variable, or the empty string if the variable is not defined.  Furthermore, input lines of the form

#cmakedefine VAR ...

will be replaced with either

#define VAR ...

or

/* #undef VAR */

depending on whether VAR is set in CMake to any value not considered a false constant by the if() command.  The "..." content on the line after the variable name, if any, is processed as above.

Unlike lines of the form #cmakedefine VAR ..., in lines of the form #cmakedefine01 VAR, VAR itself will expand to VAR 0 or VAR 1 rather than being assigned the value .... Therefore, input lines of the form

#cmakedefine01 VAR

will be replaced with either

#define VAR 0

or

#define VAR 1

Input lines of the form #cmakedefine01 VAR ... will expand as #cmakedefine01 VAR ... 0 or #cmakedefine01 VAR ... 1, which may lead to undefined behavior.

Added in version 3.10: The result lines (with the exception of the #undef comments) can be indented using spaces and/or tabs between the # character and the cmakedefine or cmakedefine01 words. This whitespace indentation will be preserved in the output lines:

#  cmakedefine VAR
#  cmakedefine01 VAR

will be replaced, if VAR is defined, with

#  define VAR
#  define VAR 1

If the input file is modified the build system will re-run CMake to re-configure the file and generate the build system again. The generated file is modified and its timestamp updated on subsequent cmake runs only if its content is changed.

The arguments are:

<input>

Path to the input file.  A relative path is treated with respect to the value of CMAKE_CURRENT_SOURCE_DIR.  The input path must be a file, not a directory.

<output>

Path to the output file or directory.  A relative path is treated with respect to the value of CMAKE_CURRENT_BINARY_DIR. If the path names an existing directory the output file is placed in that directory with the same file name as the input file. If the path contains non-existent directories, they are created.

NO_SOURCE_PERMISSIONS

Added in version 3.19.

Do not transfer the permissions of the input file to the output file. The copied file permissions default to the standard 644 value (-rw-r--r--).

USE_SOURCE_PERMISSIONS

Added in version 3.20.

Transfer the permissions of the input file to the output file. This is already the default behavior if none of the three permissions-related keywords are given (NO_SOURCE_PERMISSIONS, USE_SOURCE_PERMISSIONS or FILE_PERMISSIONS).  The USE_SOURCE_PERMISSIONS keyword mostly serves as a way of making the intended behavior clearer at the call site.

FILE_PERMISSIONS <permissions>...

Added in version 3.20.

Ignore the input file's permissions and use the specified <permissions> for the output file instead.

COPYONLY

Copy the file without replacing any variable references or other content.  This option may not be used with NEWLINE_STYLE.

ESCAPE_QUOTES

Escape any substituted quotes with backslashes (C-style).

@ONLY

Restrict variable replacement to references of the form @VAR@. This is useful for configuring scripts that use ${VAR} syntax.

NEWLINE_STYLE <style>

Specify the newline style for the output file.  Specify UNIX or LF for \n newlines, or specify DOS, WIN32, or CRLF for \r\n newlines. This option may not be used with COPYONLY.

Consider a source tree containing a foo.h.in file:

#cmakedefine FOO_ENABLE
#cmakedefine FOO_STRING "@FOO_STRING@"

An adjacent CMakeLists.txt may use configure_file to configure the header:

option(FOO_ENABLE "Enable Foo" ON)
if(FOO_ENABLE)
  set(FOO_STRING "foo")
endif()
configure_file(foo.h.in foo.h @ONLY)

This creates a foo.h in the build directory corresponding to this source directory.  If the FOO_ENABLE option is on, the configured file will contain:

#define FOO_ENABLE
#define FOO_STRING "foo"

Otherwise it will contain:

/* #undef FOO_ENABLE */
/* #undef FOO_STRING */

One may then use the target_include_directories() command to specify the output directory as an include directory:

target_include_directories(<target> [SYSTEM] <INTERFACE|PUBLIC|PRIVATE> "${CMAKE_CURRENT_BINARY_DIR}")

so that sources may include the header as #include <foo.h>.

• file(GENERATE)

Added in version 3.2.

Continue to the top of enclosing foreach or while loop.

continue()

The continue() command allows a cmake script to abort the rest of the current iteration of a foreach() or while() loop, and start at the top of the next iteration.

See also the break() command.

Starts the else portion of an if block.

else([<condition>])

See the if() command.

Starts an elseif portion of an if block.

elseif(<condition>)

See the if() command, especially for the syntax and logic of the <condition>.

Added in version 3.25.

Ends a list of commands in a block() and removes the scopes created by the block() command.

endblock()

Ends a list of commands in a foreach block.

endforeach([<loop_var>])

See the foreach() command.

The optional <loop_var> argument is supported for backward compatibility only. If used it must be a verbatim repeat of the <loop_var> argument of the opening foreach clause.

Ends a list of commands in a function block.

endfunction([<name>])

See the function() command.

The optional <name> argument is supported for backward compatibility only. If used it must be a verbatim repeat of the <name> argument of the opening function command.

Ends a list of commands in an if block.

endif([<condition>])

See the if() command.

The optional <condition> argument is supported for backward compatibility only. If used it must be a verbatim repeat of the argument of the opening if clause.

Ends a list of commands in a macro block.

endmacro([<name>])

See the macro() command.

The optional <name> argument is supported for backward compatibility only. If used it must be a verbatim repeat of the <name> argument of the opening macro command.

Ends a list of commands in a while block.

endwhile([<condition>])

See the while() command.

The optional <condition> argument is supported for backward compatibility only. If used it must be a verbatim repeat of the argument of the opening while clause.

Execute one or more child processes.

execute_process(COMMAND <cmd1> [<arguments>]
                [COMMAND <cmd2> [<arguments>]]...
                [WORKING_DIRECTORY <directory>]
                [TIMEOUT <seconds>]
                [RESULT_VARIABLE <variable>]
                [RESULTS_VARIABLE <variable>]
                [OUTPUT_VARIABLE <variable>]
                [ERROR_VARIABLE <variable>]
                [INPUT_FILE <file>]
                [OUTPUT_FILE <file>]
                [ERROR_FILE <file>]
                [OUTPUT_QUIET]
                [ERROR_QUIET]
                [COMMAND_ECHO <where>]
                [OUTPUT_STRIP_TRAILING_WHITESPACE]
                [ERROR_STRIP_TRAILING_WHITESPACE]
                [ENCODING <name>]
                [ECHO_OUTPUT_VARIABLE]
                [ECHO_ERROR_VARIABLE]
                [COMMAND_ERROR_IS_FATAL <ANY|LAST>])

Runs the given sequence of one or more commands.

Commands are executed concurrently as a pipeline, with the standard output of each process piped to the standard input of the next. A single standard error pipe is used for all processes.

execute_process runs commands while CMake is configuring the project, prior to build system generation.  Use the add_custom_target() and add_custom_command() commands to create custom commands that run at build time.

Options:

COMMAND

A child process command line.

CMake executes the child process using operating system APIs directly:

• On POSIX platforms, the command line is passed to the child process in an argv[] style array.
• On Windows platforms, the command line is encoded as a string such that child processes using CommandLineToArgvW will decode the original arguments.

No intermediate shell is used, so shell operators such as > are treated as normal arguments. (Use the INPUT_*, OUTPUT_*, and ERROR_* options to redirect stdin, stdout, and stderr.)

For sequential execution of multiple commands use multiple execute_process calls each with a single COMMAND argument.

WORKING_DIRECTORY

The named directory will be set as the current working directory of the child processes.

TIMEOUT

After the specified number of seconds (fractions allowed), all unfinished child processes will be terminated, and the RESULT_VARIABLE will be set to a string mentioning the "timeout".

RESULT_VARIABLE

The variable will be set to contain the result of last child process. This will be an integer return code from the last child or a string describing an error condition.

RESULTS_VARIABLE <variable>

Added in version 3.10.

The variable will be set to contain the result of all processes as a semicolon-separated list, in order of the given COMMAND arguments.  Each entry will be an integer return code from the corresponding child or a string describing an error condition.

INPUT_FILE <file>

<file> is attached to the standard input pipe of the first COMMAND process.

OUTPUT_FILE <file>

<file> is attached to the standard output pipe of the last COMMAND process.

ERROR_FILE <file>

<file> is attached to the standard error pipe of all COMMAND processes.

Added in version 3.3: If the same <file> is named for both OUTPUT_FILE and ERROR_FILE then it will be used for both standard output and standard error pipes.

OUTPUT_QUIET, ERROR_QUIET

The standard output on OUTPUT_VARIABLE or standard error on ERROR_VARIABLE are not connected (no variable content). The  *_FILE and ECHO_*_VARIABLE options are not affected.

OUTPUT_VARIABLE, ERROR_VARIABLE

The variable named will be set with the contents of the standard output and standard error pipes, respectively.  If the same variable is named for both pipes their output will be merged in the order produced.

ECHO_OUTPUT_VARIABLE, ECHO_ERROR_VARIABLE

Added in version 3.18.

The standard output or standard error will not be exclusively redirected to the specified variables.

The output will be duplicated into the specified variables and also onto standard output or standard error analogous to the tee Unix command.

NOTE:

If more than one OUTPUT_* or ERROR_* option is given for the same pipe the precedence is not specified. If no OUTPUT_* or ERROR_* options are given the output will be shared with the corresponding pipes of the CMake process itself.

COMMAND_ECHO <where>

Added in version 3.15.

The command being run will be echo'ed to <where> with <where> being set to one of STDERR, STDOUT or NONE. See the CMAKE_EXECUTE_PROCESS_COMMAND_ECHO variable for a way to control the default behavior when this option is not present.

ENCODING <name>

Added in version 3.8.

On Windows, the encoding that is used to decode output from the process. Ignored on other platforms. Valid encoding names are:

NONE

Perform no decoding.  This assumes that the process output is encoded in the same way as CMake's internal encoding (UTF-8). This is the default.

AUTO

Use the current active console's codepage or if that isn't available then use ANSI.

ANSI

Use the ANSI codepage.

OEM

Use the original equipment manufacturer (OEM) code page.

UTF8 or UTF-8

Use the UTF-8 codepage.

Added in version 3.11: Accept UTF-8 spelling for consistency with the UTF-8 RFC naming convention.

COMMAND_ERROR_IS_FATAL <ANY|LAST>

Added in version 3.19.

The option following COMMAND_ERROR_IS_FATAL determines the behavior when an error is encountered:

ANY If any of the commands in the list of commands fail, the execute_process() command halts with an error.

LAST If the last command in the list of commands fails, the execute_process() command halts with an error.  Commands earlier in the list will not cause a fatal error.

File manipulation command.

This command is dedicated to file and path manipulation requiring access to the filesystem.

For other path manipulation, handling only syntactic aspects, have a look at cmake_path() command.

NOTE:

Reading
  file(READ <filename> <out-var> [...])
  file(STRINGS <filename> <out-var> [...])
  file(<HASH> <filename> <out-var>)
  file(TIMESTAMP <filename> <out-var> [...])
  file(GET_RUNTIME_DEPENDENCIES [...])

Writing
  file({WRITE | APPEND} <filename> <content>...)
  file({TOUCH | TOUCH_NOCREATE} [<file>...])
  file(GENERATE OUTPUT <output-file> [...])
  file(CONFIGURE OUTPUT <output-file> CONTENT <content> [...])

Filesystem
  file({GLOB | GLOB_RECURSE} <out-var> [...] [<globbing-expr>...])
  file(MAKE_DIRECTORY [<dir>...])
  file({REMOVE | REMOVE_RECURSE } [<files>...])
  file(RENAME <oldname> <newname> [...])
  file(COPY_FILE <oldname> <newname> [...])
  file({COPY | INSTALL} <file>... DESTINATION <dir> [...])
  file(SIZE <filename> <out-var>)
  file(READ_SYMLINK <linkname> <out-var>)
  file(CREATE_LINK <original> <linkname> [...])
  file(CHMOD <files>... <directories>... PERMISSIONS <permissions>... [...])
  file(CHMOD_RECURSE <files>... <directories>... PERMISSIONS <permissions>... [...])

Path Conversion
  file(REAL_PATH <path> <out-var> [BASE_DIRECTORY <dir>] [EXPAND_TILDE])
  file(RELATIVE_PATH <out-var> <directory> <file>)
  file({TO_CMAKE_PATH | TO_NATIVE_PATH} <path> <out-var>)

Transfer
  file(DOWNLOAD <url> [<file>] [...])
  file(UPLOAD <file> <url> [...])

Locking
  file(LOCK <path> [...])

Archiving
  file(ARCHIVE_CREATE OUTPUT <archive> PATHS <paths>... [...])
  file(ARCHIVE_EXTRACT INPUT <archive> [...])

file(READ <filename> <variable> [OFFSET <offset>] [LIMIT <max-in>] [HEX])

Read content from a file called <filename> and store it in a <variable>.  Optionally start from the given <offset> and read at most <max-in> bytes.  The HEX option causes data to be converted to a hexadecimal representation (useful for binary data). If the HEX option is specified, letters in the output (a through f) are in lowercase.

file(STRINGS <filename> <variable> [<options>...])

Parse a list of ASCII strings from <filename> and store it in <variable>.  Binary data in the file are ignored.  Carriage return (\r, CR) characters are ignored.  The options are:

LENGTH_MAXIMUM <max-len>

Consider only strings of at most a given length.

LENGTH_MINIMUM <min-len>

Consider only strings of at least a given length.

LIMIT_COUNT <max-num>

Limit the number of distinct strings to be extracted.

LIMIT_INPUT <max-in>

Limit the number of input bytes to read from the file.

LIMIT_OUTPUT <max-out>

Limit the number of total bytes to store in the <variable>.

NEWLINE_CONSUME

Treat newline characters (\n, LF) as part of string content instead of terminating at them.

NO_HEX_CONVERSION

Intel Hex and Motorola S-record files are automatically converted to binary while reading unless this option is given.

REGEX <regex>

Consider only strings that match the given regular expression, as described under string(REGEX).

ENCODING <encoding-type>

Added in version 3.1.

Consider strings of a given encoding.  Currently supported encodings are: UTF-8, UTF-16LE, UTF-16BE, UTF-32LE, UTF-32BE. If the ENCODING option is not provided and the file has a Byte Order Mark, the ENCODING option will be defaulted to respect the Byte Order Mark.

Added in version 3.2: Added the UTF-16LE, UTF-16BE, UTF-32LE, UTF-32BE encodings.

For example, the code

file(STRINGS myfile.txt myfile)

stores a list in the variable myfile in which each item is a line from the input file.

file(<HASH> <filename> <variable>)

Compute a cryptographic hash of the content of <filename> and store it in a <variable>.  The supported <HASH> algorithm names are those listed by the string(<HASH>) command.

file(TIMESTAMP <filename> <variable> [<format>] [UTC])

Compute a string representation of the modification time of <filename> and store it in <variable>.  Should the command be unable to obtain a timestamp variable will be set to the empty string ("").

See the string(TIMESTAMP) command for documentation of the <format> and UTC options.

file(GET_RUNTIME_DEPENDENCIES [...])

Added in version 3.16.

Recursively get the list of libraries depended on by the given files:

file(GET_RUNTIME_DEPENDENCIES
  [RESOLVED_DEPENDENCIES_VAR <deps_var>]
  [UNRESOLVED_DEPENDENCIES_VAR <unresolved_deps_var>]
  [CONFLICTING_DEPENDENCIES_PREFIX <conflicting_deps_prefix>]
  [EXECUTABLES [<executable_files>...]]
  [LIBRARIES [<library_files>...]]
  [MODULES [<module_files>...]]
  [DIRECTORIES [<directories>...]]
  [BUNDLE_EXECUTABLE <bundle_executable_file>]
  [PRE_INCLUDE_REGEXES [<regexes>...]]
  [PRE_EXCLUDE_REGEXES [<regexes>...]]
  [POST_INCLUDE_REGEXES [<regexes>...]]
  [POST_EXCLUDE_REGEXES [<regexes>...]]
  [POST_INCLUDE_FILES [<files>...]]
  [POST_EXCLUDE_FILES [<files>...]]
  )

Please note that this sub-command is not intended to be used in project mode. It is intended for use at install time, either from code generated by the install(RUNTIME_DEPENDENCY_SET) command, or from code provided by the project via install(CODE) or install(SCRIPT). For example:

install(CODE [[
  file(GET_RUNTIME_DEPENDENCIES
    # ...
    )
  ]])

The arguments are as follows:

RESOLVED_DEPENDENCIES_VAR <deps_var>

Name of the variable in which to store the list of resolved dependencies.

UNRESOLVED_DEPENDENCIES_VAR <unresolved_deps_var>

Name of the variable in which to store the list of unresolved dependencies. If this variable is not specified, and there are any unresolved dependencies, an error is issued.

CONFLICTING_DEPENDENCIES_PREFIX <conflicting_deps_prefix>

Variable prefix in which to store conflicting dependency information. Dependencies are conflicting if two files with the same name are found in two different directories. The list of filenames that conflict are stored in <conflicting_deps_prefix>_FILENAMES. For each filename, the list of paths that were found for that filename are stored in <conflicting_deps_prefix>_<filename>.

EXECUTABLES <executable_files>

List of executable files to read for dependencies. These are executables that are typically created with add_executable(), but they do not have to be created by CMake. On Apple platforms, the paths to these files determine the value of @executable_path when recursively resolving the libraries. Specifying any kind of library (STATIC, MODULE, or SHARED) here will result in undefined behavior.

LIBRARIES <library_files>

List of library files to read for dependencies. These are libraries that are typically created with add_library(SHARED), but they do not have to be created by CMake. Specifying STATIC libraries, MODULE libraries, or executables here will result in undefined behavior.

MODULES <module_files>

List of loadable module files to read for dependencies. These are modules that are typically created with add_library(MODULE), but they do not have to be created by CMake. They are typically used by calling dlopen() at runtime rather than linked at link time with ld -l. Specifying STATIC libraries, SHARED libraries, or executables here will result in undefined behavior.

DIRECTORIES <directories>

List of additional directories to search for dependencies. On Linux platforms, these directories are searched if the dependency is not found in any of the other usual paths. If it is found in such a directory, a warning is issued, because it means that the file is incomplete (it does not list all of the directories that contain its dependencies). On Windows platforms, these directories are searched if the dependency is not found in any of the other search paths, but no warning is issued, because searching other paths is a normal part of Windows dependency resolution. On Apple platforms, this argument has no effect.

BUNDLE_EXECUTABLE <bundle_executable_file>

Executable to treat as the "bundle executable" when resolving libraries. On Apple platforms, this argument determines the value of @executable_path when recursively resolving libraries for LIBRARIES and MODULES files. It has no effect on EXECUTABLES files. On other platforms, it has no effect. This is typically (but not always) one of the executables in the EXECUTABLES argument which designates the "main" executable of the package.

The following arguments specify filters for including or excluding libraries to be resolved. See below for a full description of how they work.

PRE_INCLUDE_REGEXES <regexes>

List of pre-include regexes through which to filter the names of not-yet-resolved dependencies.

PRE_EXCLUDE_REGEXES <regexes>

List of pre-exclude regexes through which to filter the names of not-yet-resolved dependencies.

POST_INCLUDE_REGEXES <regexes>

List of post-include regexes through which to filter the names of resolved dependencies.

POST_EXCLUDE_REGEXES <regexes>

List of post-exclude regexes through which to filter the names of resolved dependencies.

POST_INCLUDE_FILES <files>

Added in version 3.21.

List of post-include filenames through which to filter the names of resolved dependencies. Symlinks are resolved when attempting to match these filenames.

POST_EXCLUDE_FILES <files>

Added in version 3.21.

List of post-exclude filenames through which to filter the names of resolved dependencies. Symlinks are resolved when attempting to match these filenames.

These arguments can be used to exclude unwanted system libraries when resolving the dependencies, or to include libraries from a specific directory. The filtering works as follows:

1. If the not-yet-resolved dependency matches any of the PRE_INCLUDE_REGEXES, steps 2 and 3 are skipped, and the dependency resolution proceeds to step 4.
2. If the not-yet-resolved dependency matches any of the PRE_EXCLUDE_REGEXES, dependency resolution stops for that dependency.
3. Otherwise, dependency resolution proceeds.
4. file(GET_RUNTIME_DEPENDENCIES) searches for the dependency according to the linking rules of the platform (see below).
5. If the dependency is found, and its full path matches one of the POST_INCLUDE_REGEXES or POST_INCLUDE_FILES, the full path is added to the resolved dependencies, and file(GET_RUNTIME_DEPENDENCIES) recursively resolves that library's own dependencies. Otherwise, resolution proceeds to step 6.
6. If the dependency is found, but its full path matches one of the POST_EXCLUDE_REGEXES or POST_EXCLUDE_FILES, it is not added to the resolved dependencies, and dependency resolution stops for that dependency.
7. If the dependency is found, and its full path does not match either POST_INCLUDE_REGEXES, POST_INCLUDE_FILES, POST_EXCLUDE_REGEXES, or POST_EXCLUDE_FILES, the full path is added to the resolved dependencies, and file(GET_RUNTIME_DEPENDENCIES)  recursively resolves that library's own dependencies.

Different platforms have different rules for how dependencies are resolved. These specifics are described here.

On Linux platforms, library resolution works as follows:

1. If the depending file does not have any RUNPATH entries, and the library exists in one of the depending file's RPATH entries, or its parents', in that order, the dependency is resolved to that file.
2. Otherwise, if the depending file has any RUNPATH entries, and the library exists in one of those entries, the dependency is resolved to that file.
3. Otherwise, if the library exists in one of the directories listed by ldconfig, the dependency is resolved to that file.
4. Otherwise, if the library exists in one of the DIRECTORIES entries, the dependency is resolved to that file. In this case, a warning is issued, because finding a file in one of the DIRECTORIES means that the depending file is not complete (it does not list all the directories from which it pulls dependencies).
5. Otherwise, the dependency is unresolved.

On Windows platforms, library resolution works as follows:

1. DLL dependency names are converted to lowercase for matching filters. Windows DLL names are case-insensitive, and some linkers mangle the case of the DLL dependency names.  However, this makes it more difficult for PRE_INCLUDE_REGEXES, PRE_EXCLUDE_REGEXES, POST_INCLUDE_REGEXES, and POST_EXCLUDE_REGEXES to properly filter DLL names - every regex would have to check for both uppercase and lowercase letters.  For example:

   file(GET_RUNTIME_DEPENDENCIES
     # ...
     PRE_INCLUDE_REGEXES "^[Mm][Yy][Ll][Ii][Bb][Rr][Aa][Rr][Yy]\\.[Dd][Ll][Ll]$"
     )

   Converting the DLL name to lowercase allows the regexes to only match lowercase names, thus simplifying the regex. For example:

   file(GET_RUNTIME_DEPENDENCIES
     # ...
     PRE_INCLUDE_REGEXES "^mylibrary\\.dll$"
     )

   This regex will match mylibrary.dll regardless of how it is cased, either on disk or in the depending file. (For example, it will match mylibrary.dll, MyLibrary.dll, and MYLIBRARY.DLL.)

   Changed in version 3.27: The conversion to lowercase only applies while matching filters. Results reported after filtering case-preserve each DLL name as it is found on disk, if resolved, and otherwise as it is referenced by the dependent binary.

   Prior to CMake 3.27, the results were reported with lowercase DLL file names, but the directory portion retained its casing.

2. (Not yet implemented) If the depending file is a Windows Store app, and the dependency is listed as a dependency in the application's package manifest, the dependency is resolved to that file.
3. Otherwise, if the library exists in the same directory as the depending file, the dependency is resolved to that file.
4. Otherwise, if the library exists in either the operating system's system32 directory or the Windows directory, in that order, the dependency is resolved to that file.
5. Otherwise, if the library exists in one of the directories specified by DIRECTORIES, in the order they are listed, the dependency is resolved to that file. In this case, a warning is not issued, because searching other directories is a normal part of Windows library resolution.
6. Otherwise, the dependency is unresolved.

On Apple platforms, library resolution works as follows:

1. If the dependency starts with @executable_path/, and an EXECUTABLES argument is in the process of being resolved, and replacing @executable_path/ with the directory of the executable yields an existing file, the dependency is resolved to that file.
2. Otherwise, if the dependency starts with @executable_path/, and there is a BUNDLE_EXECUTABLE argument, and replacing @executable_path/ with the directory of the bundle executable yields an existing file, the dependency is resolved to that file.
3. Otherwise, if the dependency starts with @loader_path/, and replacing @loader_path/ with the directory of the depending file yields an existing file, the dependency is resolved to that file.
4. Otherwise, if the dependency starts with @rpath/, and replacing @rpath/ with one of the RPATH entries of the depending file yields an existing file, the dependency is resolved to that file. Note that RPATH entries that start with @executable_path/ or @loader_path/ also have these items replaced with the appropriate path.
5. Otherwise, if the dependency is an absolute file that exists, the dependency is resolved to that file.
6. Otherwise, the dependency is unresolved.

This function accepts several variables that determine which tool is used for dependency resolution:

CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM

Determines which operating system and executable format the files are built for. This could be one of several values:

• linux+elf
• windows+pe
• macos+macho

If this variable is not specified, it is determined automatically by system introspection.

CMAKE_GET_RUNTIME_DEPENDENCIES_TOOL

Determines the tool to use for dependency resolution. It could be one of several values, depending on the value of CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM:

CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM	CMAKE_GET_RUNTIME_DEPENDENCIES_TOOL
linux+elf	objdump
windows+pe	objdump or dumpbin
macos+macho	otool

If this variable is not specified, it is determined automatically by system introspection.

CMAKE_GET_RUNTIME_DEPENDENCIES_COMMAND

Determines the path to the tool to use for dependency resolution. This is the actual path to objdump, dumpbin, or otool.

If this variable is not specified, it is determined by the value of CMAKE_OBJDUMP if set, else by system introspection.

Added in version 3.18: Use CMAKE_OBJDUMP if set.

file(WRITE <filename> <content>...)

file(APPEND <filename> <content>...)

Write <content> into a file called <filename>.  If the file does not exist, it will be created.  If the file already exists, WRITE mode will overwrite it and APPEND mode will append to the end. Any directories in the path specified by <filename> that do not exist will be created.

If the file is a build input, use the configure_file() command to update the file only when its content changes.

file(TOUCH [<files>...])

file(TOUCH_NOCREATE [<files>...])

Added in version 3.12.

Create a file with no content if it does not yet exist. If the file already exists, its access and/or modification will be updated to the time when the function call is executed.

Use TOUCH_NOCREATE to touch a file if it exists but not create it. If a file does not exist it will be silently ignored.

With TOUCH and TOUCH_NOCREATE, the contents of an existing file will not be modified.

file(GENERATE [...])

Generate an output file for each build configuration supported by the current CMake Generator.  Evaluate generator expressions from the input content to produce the output content.

file(GENERATE OUTPUT <output-file>
     <INPUT <input-file>|CONTENT <content>>
     [CONDITION <expression>] [TARGET <target>]
     [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS |
      FILE_PERMISSIONS <permissions>...]
     [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])

The options are:

CONDITION <condition>

Generate the output file for a particular configuration only if the condition is true.  The condition must be either 0 or 1 after evaluating generator expressions.

CONTENT <content>

Use the content given explicitly as input.

INPUT <input-file>

Use the content from a given file as input.

Changed in version 3.10: A relative path is treated with respect to the value of CMAKE_CURRENT_SOURCE_DIR.  See policy CMP0070.

OUTPUT <output-file>

Specify the output file name to generate.  Use generator expressions such as $<CONFIG> to specify a configuration-specific output file name.  Multiple configurations may generate the same output file only if the generated content is identical.  Otherwise, the <output-file> must evaluate to an unique name for each configuration.

Changed in version 3.10: A relative path (after evaluating generator expressions) is treated with respect to the value of CMAKE_CURRENT_BINARY_DIR. See policy CMP0070.

TARGET <target>

Added in version 3.19.

Specify which target to use when evaluating generator expressions that require a target for evaluation (e.g. $<COMPILE_FEATURES:...>, $<TARGET_PROPERTY:prop>).

NO_SOURCE_PERMISSIONS

Added in version 3.20.

The generated file permissions default to the standard 644 value (-rw-r--r--).

USE_SOURCE_PERMISSIONS

Added in version 3.20.

Transfer the file permissions of the INPUT file to the generated file. This is already the default behavior if none of the three permissions-related keywords are given (NO_SOURCE_PERMISSIONS, USE_SOURCE_PERMISSIONS or FILE_PERMISSIONS).  The USE_SOURCE_PERMISSIONS keyword mostly serves as a way of making the intended behavior clearer at the call site. It is an error to specify this option without INPUT.

FILE_PERMISSIONS <permissions>...

Added in version 3.20.

Use the specified permissions for the generated file.

NEWLINE_STYLE <style>

Added in version 3.20.

Specify the newline style for the generated file.  Specify UNIX or LF for \n newlines, or specify DOS, WIN32, or CRLF for \r\n newlines.

Exactly one CONTENT or INPUT option must be given.  A specific OUTPUT file may be named by at most one invocation of file(GENERATE). Generated files are modified and their timestamp updated on subsequent cmake runs only if their content is changed.

Note also that file(GENERATE) does not create the output file until the generation phase. The output file will not yet have been written when the file(GENERATE) command returns, it is written only after processing all of a project's CMakeLists.txt files.

file(CONFIGURE OUTPUT <output-file> CONTENT <content> [ESCAPE_QUOTES] [@ONLY] [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])

Added in version 3.18.

Generate an output file using the input given by CONTENT and substitute variable values referenced as @VAR@ or ${VAR} contained therein. The substitution rules behave the same as the configure_file() command. In order to match configure_file()'s behavior, generator expressions are not supported for both OUTPUT and CONTENT.

The arguments are:

OUTPUT <output-file>

Specify the output file name to generate. A relative path is treated with respect to the value of CMAKE_CURRENT_BINARY_DIR. <output-file> does not support generator expressions.

CONTENT <content>

Use the content given explicitly as input. <content> does not support generator expressions.

ESCAPE_QUOTES

Escape any substituted quotes with backslashes (C-style).

@ONLY

Restrict variable replacement to references of the form @VAR@. This is useful for configuring scripts that use ${VAR} syntax.

NEWLINE_STYLE <style>

Specify the newline style for the output file.  Specify UNIX or LF for \n newlines, or specify DOS, WIN32, or CRLF for \r\n newlines.

file(GLOB <variable> [LIST_DIRECTORIES true|false] [RELATIVE <path>] [CONFIGURE_DEPENDS] [<globbing-expressions>...])

file(GLOB_RECURSE <variable> [FOLLOW_SYMLINKS] [LIST_DIRECTORIES true|false] [RELATIVE <path>] [CONFIGURE_DEPENDS] [<globbing-expressions>...])

Generate a list of files that match the <globbing-expressions> and store it into the <variable>.  Globbing expressions are similar to regular expressions, but much simpler.  If RELATIVE flag is specified, the results will be returned as relative paths to the given path.

Changed in version 3.6: The results will be ordered lexicographically.

On Windows and macOS, globbing is case-insensitive even if the underlying filesystem is case-sensitive (both filenames and globbing expressions are converted to lowercase before matching).  On other platforms, globbing is case-sensitive.

Added in version 3.3: By default GLOB lists directories. Directories are omitted in the result if LIST_DIRECTORIES is set to false.

Added in version 3.12: If the CONFIGURE_DEPENDS flag is specified, CMake will add logic to the main build system check target to rerun the flagged GLOB commands at build time. If any of the outputs change, CMake will regenerate the build system.

NOTE:

We do not recommend using GLOB to collect a list of source files from your source tree.  If no CMakeLists.txt file changes when a source is added or removed then the generated build system cannot know when to ask CMake to regenerate. The CONFIGURE_DEPENDS flag may not work reliably on all generators, or if a new generator is added in the future that cannot support it, projects using it will be stuck. Even if CONFIGURE_DEPENDS works reliably, there is still a cost to perform the check on every rebuild.

Examples of globbing expressions include:

*.cxx	match all files with extension cxx
*.vt?	match all files with extension vta, ..., vtz
f[3-5].txt	match files f3.txt, f4.txt, f5.txt

The GLOB_RECURSE mode will traverse all the subdirectories of the matched directory and match the files.  Subdirectories that are symlinks are only traversed if FOLLOW_SYMLINKS is given or policy CMP0009 is not set to NEW.

Added in version 3.3: By default GLOB_RECURSE omits directories from result list. Setting LIST_DIRECTORIES to true adds directories to result list. If FOLLOW_SYMLINKS is given or policy CMP0009 is not set to NEW then LIST_DIRECTORIES treats symlinks as directories.

Examples of recursive globbing include:

/dir/*.py

match all python files in /dir and subdirectories

file(MAKE_DIRECTORY [<directories>...])

Create the given directories and their parents as needed.

file(REMOVE [<files>...])

file(REMOVE_RECURSE [<files>...])

Remove the given files.  The REMOVE_RECURSE mode will remove the given files and directories, including non-empty directories. No error is emitted if a given file does not exist.  Relative input paths are evaluated with respect to the current source directory.

Changed in version 3.15: Empty input paths are ignored with a warning.  Previous versions of CMake interpreted empty strings as a relative path with respect to the current directory and removed its contents.

file(RENAME <oldname> <newname> [RESULT <result>] [NO_REPLACE])

Move a file or directory within a filesystem from <oldname> to <newname>, replacing the destination atomically.

The options are:

RESULT <result>

Added in version 3.21.

Set <result> variable to 0 on success or an error message otherwise. If RESULT is not specified and the operation fails, an error is emitted.

NO_REPLACE

Added in version 3.21.

If the <newname> path already exists, do not replace it. If RESULT <result> is used, the result variable will be set to NO_REPLACE.  Otherwise, an error is emitted.

file(COPY_FILE <oldname> <newname> [RESULT <result>] [ONLY_IF_DIFFERENT] [INPUT_MAY_BE_RECENT])

Added in version 3.21.

Copy a file from <oldname> to <newname>. Directories are not supported. Symlinks are ignored and <oldfile>'s content is read and written to <newname> as a new file.

The options are:

RESULT <result>

Set <result> variable to 0 on success or an error message otherwise.  If RESULT is not specified and the operation fails, an error is emitted.

ONLY_IF_DIFFERENT

If the <newname> path already exists, do not replace it if the file's contents are already the same as <oldname> (this avoids updating <newname>'s timestamp).

INPUT_MAY_BE_RECENT

Added in version 3.26.

Tell CMake that the input file may have been recently created.  This is meaningful only on Windows, where files may be inaccessible for a short time after they are created.  With this option, if permission is denied, CMake will retry reading the input a few times.

This sub-command has some similarities to configure_file() with the COPYONLY option.  An important difference is that configure_file() creates a dependency on the source file, so CMake will be re-run if it changes. The file(COPY_FILE) sub-command does not create such a dependency.

See also the file(COPY) sub-command just below which provides further file-copying capabilities.

file(COPY [...])

file(INSTALL [...])

The COPY signature copies files, directories, and symlinks to a destination folder.  Relative input paths are evaluated with respect to the current source directory, and a relative destination is evaluated with respect to the current build directory.  Copying preserves input file timestamps, and optimizes out a file if it exists at the destination with the same timestamp.  Copying preserves input permissions unless explicit permissions or NO_SOURCE_PERMISSIONS are given (default is USE_SOURCE_PERMISSIONS).

file(<COPY|INSTALL> <files>... DESTINATION <dir>
     [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS]
     [FILE_PERMISSIONS <permissions>...]
     [DIRECTORY_PERMISSIONS <permissions>...]
     [FOLLOW_SYMLINK_CHAIN]
     [FILES_MATCHING]
     [[PATTERN <pattern> | REGEX <regex>]
      [EXCLUDE] [PERMISSIONS <permissions>...]] [...])

NOTE:

For a simple file copying operation, the file(COPY_FILE) sub-command just above may be easier to use.

Added in version 3.15: If FOLLOW_SYMLINK_CHAIN is specified, COPY will recursively resolve the symlinks at the paths given until a real file is found, and install a corresponding symlink in the destination for each symlink encountered. For each symlink that is installed, the resolution is stripped of the directory, leaving only the filename, meaning that the new symlink points to a file in the same directory as the symlink. This feature is useful on some Unix systems, where libraries are installed as a chain of symlinks with version numbers, with less specific versions pointing to more specific versions. FOLLOW_SYMLINK_CHAIN will install all of these symlinks and the library itself into the destination directory. For example, if you have the following directory structure:

• /opt/foo/lib/libfoo.so.1.2.3
• /opt/foo/lib/libfoo.so.1.2 -> libfoo.so.1.2.3
• /opt/foo/lib/libfoo.so.1 -> libfoo.so.1.2
• /opt/foo/lib/libfoo.so -> libfoo.so.1

and you do:

file(COPY /opt/foo/lib/libfoo.so DESTINATION lib FOLLOW_SYMLINK_CHAIN)

This will install all of the symlinks and libfoo.so.1.2.3 itself into lib.

See the install(DIRECTORY) command for documentation of permissions, FILES_MATCHING, PATTERN, REGEX, and EXCLUDE options.  Copying directories preserves the structure of their content even if options are used to select a subset of files.

The INSTALL signature differs slightly from COPY: it prints status messages, and NO_SOURCE_PERMISSIONS is default. Installation scripts generated by the install() command use this signature (with some undocumented options for internal use).

Changed in version 3.22: The environment variable CMAKE_INSTALL_MODE can override the default copying behavior of file(INSTALL).

file(SIZE <filename> <variable>)

Added in version 3.14.

Determine the file size of the <filename> and put the result in <variable> variable. Requires that <filename> is a valid path pointing to a file and is readable.

file(READ_SYMLINK <linkname> <variable>)

Added in version 3.14.

Query the symlink <linkname> and stores the path it points to in the result <variable>.  If <linkname> does not exist or is not a symlink, CMake issues a fatal error.

Note that this command returns the raw symlink path and does not resolve a relative path.  The following is an example of how to ensure that an absolute path is obtained:

set(linkname "/path/to/foo.sym")
file(READ_SYMLINK "${linkname}" result)
if(NOT IS_ABSOLUTE "${result}")
  get_filename_component(dir "${linkname}" DIRECTORY)
  set(result "${dir}/${result}")
endif()

file(CREATE_LINK <original> <linkname> [RESULT <result>] [COPY_ON_ERROR] [SYMBOLIC])

Added in version 3.14.

Create a link <linkname> that points to <original>. It will be a hard link by default, but providing the SYMBOLIC option results in a symbolic link instead.  Hard links require that original exists and is a file, not a directory.  If <linkname> already exists, it will be overwritten.

The <result> variable, if specified, receives the status of the operation.  It is set to 0 upon success or an error message otherwise. If RESULT is not specified and the operation fails, a fatal error is emitted.

Specifying COPY_ON_ERROR enables copying the file as a fallback if creating the link fails.  It can be useful for handling situations such as <original> and <linkname> being on different drives or mount points, which would make them unable to support a hard link.

file(CHMOD <files>... <directories>... [PERMISSIONS <permissions>...] [FILE_PERMISSIONS <permissions>...] [DIRECTORY_PERMISSIONS <permissions>...])

Added in version 3.19.

Set the permissions for the <files>... and <directories>... specified. Valid permissions are  OWNER_READ, OWNER_WRITE, OWNER_EXECUTE, GROUP_READ, GROUP_WRITE, GROUP_EXECUTE, WORLD_READ, WORLD_WRITE, WORLD_EXECUTE, SETUID, SETGID.

Valid combination of keywords are:

PERMISSIONS

All items are changed.

FILE_PERMISSIONS

Only files are changed.

DIRECTORY_PERMISSIONS

Only directories are changed.

PERMISSIONS and FILE_PERMISSIONS

FILE_PERMISSIONS overrides PERMISSIONS for files.

PERMISSIONS and DIRECTORY_PERMISSIONS

DIRECTORY_PERMISSIONS overrides PERMISSIONS for directories.

FILE_PERMISSIONS and DIRECTORY_PERMISSIONS

Use FILE_PERMISSIONS for files and DIRECTORY_PERMISSIONS for directories.

file(CHMOD_RECURSE <files>... <directories>... [PERMISSIONS <permissions>...] [FILE_PERMISSIONS <permissions>...] [DIRECTORY_PERMISSIONS <permissions>...])

Added in version 3.19.

Same as CHMOD, but change the permissions of files and directories present in the <directories>... recursively.

file(REAL_PATH <path> <out-var> [BASE_DIRECTORY <dir>] [EXPAND_TILDE])

Added in version 3.19.

Compute the absolute path to an existing file or directory with symlinks resolved.  The options are:

BASE_DIRECTORY <dir>

If the provided <path> is a relative path, it is evaluated relative to the given base directory <dir>. If no base directory is provided, the default base directory will be CMAKE_CURRENT_SOURCE_DIR.

EXPAND_TILDE

Added in version 3.21.

If the <path> is ~ or starts with ~/, the ~ is replaced by the user's home directory.  The path to the home directory is obtained from environment variables.  On Windows, the USERPROFILE environment variable is used, falling back to the HOME environment variable if USERPROFILE is not defined.  On all other platforms, only HOME is used.

Changed in version 3.28: All symlinks are resolved before collapsing ../ components. See policy CMP0152.

file(RELATIVE_PATH <variable> <directory> <file>)

Compute the relative path from a <directory> to a <file> and store it in the <variable>.

file(TO_CMAKE_PATH "<path>" <variable>)

file(TO_NATIVE_PATH "<path>" <variable>)

The TO_CMAKE_PATH mode converts a native <path> into a cmake-style path with forward-slashes (/).  The input can be a single path or a system search path like $ENV{PATH}.  A search path will be converted to a cmake-style list separated by ; characters.

The TO_NATIVE_PATH mode converts a cmake-style <path> into a native path with platform-specific slashes (\ on Windows hosts and / elsewhere).

Always use double quotes around the <path> to be sure it is treated as a single argument to this command.

file(DOWNLOAD <url> [<file>] [<options>...])

file(UPLOAD <file> <url> [<options>...])

The DOWNLOAD subcommand downloads the given <url> to a local <file>.  The UPLOAD mode uploads a local <file> to a given <url>.

Added in version 3.19: If <file> is not specified for file(DOWNLOAD), the file is not saved. This can be useful if you want to know if a file can be downloaded (for example, to check that it exists) without actually saving it anywhere.

Options to both DOWNLOAD and UPLOAD are:

INACTIVITY_TIMEOUT <seconds>

Terminate the operation after a period of inactivity.

LOG <variable>

Store a human-readable log of the operation in a variable.

SHOW_PROGRESS

Print progress information as status messages until the operation is complete.

STATUS <variable>

Store the resulting status of the operation in a variable. The status is a ; separated list of length 2. The first element is the numeric return value for the operation, and the second element is a string value for the error. A 0 numeric error means no error in the operation.

TIMEOUT <seconds>

Terminate the operation after a given total time has elapsed.

USERPWD <username>:<password>

Added in version 3.7.

Set username and password for operation.

HTTPHEADER <HTTP-header>

Added in version 3.7.

HTTP header for DOWNLOAD and UPLOAD operations. HTTPHEADER can be repeated for multiple options:

file(DOWNLOAD <url>
     HTTPHEADER "Authorization: Bearer <auth-token>"
     HTTPHEADER "UserAgent: Mozilla/5.0")

NETRC <level>

Added in version 3.11.

Specify whether the .netrc file is to be used for operation.  If this option is not specified, the value of the CMAKE_NETRC variable will be used instead.

Valid levels are:

IGNORED

The .netrc file is ignored. This is the default.

OPTIONAL

The .netrc file is optional, and information in the URL is preferred. The file will be scanned to find which ever information is not specified in the URL.

REQUIRED

The .netrc file is required, and information in the URL is ignored.

NETRC_FILE <file>

Added in version 3.11.

Specify an alternative .netrc file to the one in your home directory, if the NETRC level is OPTIONAL or REQUIRED. If this option is not specified, the value of the CMAKE_NETRC_FILE variable will be used instead.

TLS_VERIFY <ON|OFF>

Specify whether to verify the server certificate for https:// URLs. The default is to not verify. If this option is not specified, the value of the CMAKE_TLS_VERIFY variable will be used instead.

Added in version 3.18: Added support to file(UPLOAD).

TLS_CAINFO <file>

Specify a custom Certificate Authority file for https:// URLs. If this option is not specified, the value of the CMAKE_TLS_CAINFO variable will be used instead.

Added in version 3.18: Added support to file(UPLOAD).

For https:// URLs CMake must be built with OpenSSL support.  TLS/SSL certificates are not checked by default.  Set TLS_VERIFY to ON to check certificates.

Additional options to DOWNLOAD are:

EXPECTED_HASH <algorithm>=<value>

Verify that the downloaded content hash matches the expected value, where <algorithm> is one of the algorithms supported by <HASH>. If the file already exists and matches the hash, the download is skipped. If the file already exists and does not match the hash, the file is downloaded again. If after download the file does not match the hash, the operation fails with an error. It is an error to specify this option if DOWNLOAD is not given a <file>.

EXPECTED_MD5 <value>

Historical short-hand for EXPECTED_HASH MD5=<value>. It is an error to specify this if DOWNLOAD is not given a <file>.

RANGE_START <value>

Added in version 3.24.

Offset of the start of the range in file in bytes. Could be omitted to download up to the specified RANGE_END.

RANGE_END <value>

Added in version 3.24.

Offset of the end of the range in file in bytes. Could be omitted to download everything from the specified RANGE_START to the end of file.

file(LOCK <path> [DIRECTORY] [RELEASE] [GUARD <FUNCTION|FILE|PROCESS>] [RESULT_VARIABLE <variable>] [TIMEOUT <seconds>])

Added in version 3.2.

Lock a file specified by <path> if no DIRECTORY option present and file <path>/cmake.lock otherwise.  The file will be locked for the scope defined by the GUARD option (default value is PROCESS).  The RELEASE option can be used to unlock the file explicitly.  If the TIMEOUT option is not specified, CMake will wait until the lock succeeds or until a fatal error occurs.  If TIMEOUT is set to 0, locking will be tried once and the result will be reported immediately.  If TIMEOUT is not 0, CMake will try to lock the file for the period specified by the TIMEOUT <seconds> value.  Any errors will be interpreted as fatal if there is no RESULT_VARIABLE option.  Otherwise, the result will be stored in <variable> and will be 0 on success or an error message on failure.

Note that lock is advisory; there is no guarantee that other processes will respect this lock, i.e. lock synchronize two or more CMake instances sharing some modifiable resources. Similar logic applies to the DIRECTORY option; locking a parent directory doesn't prevent other LOCK commands from locking any child directory or file.

Trying to lock the same file twice is not allowed.  Any intermediate directories and the file itself will be created if they not exist.  The GUARD and TIMEOUT options are ignored on the RELEASE operation.

file(ARCHIVE_CREATE OUTPUT <archive> PATHS <paths>... [FORMAT <format>] [COMPRESSION <compression> [COMPRESSION_LEVEL <compression-level>]] [MTIME <mtime>] [VERBOSE])

Added in version 3.18.

Creates the specified <archive> file with the files and directories listed in <paths>.  Note that <paths> must list actual files or directories; wildcards are not supported.

Use the FORMAT option to specify the archive format.  Supported values for <format> are 7zip, gnutar, pax, paxr, raw and zip.  If FORMAT is not given, the default format is paxr.

Some archive formats allow the type of compression to be specified. The 7zip and zip archive formats already imply a specific type of compression.  The other formats use no compression by default, but can be directed to do so with the COMPRESSION option.  Valid values for <compression> are None, BZip2, GZip, XZ, and Zstd.

Added in version 3.19: The compression level can be specified with the COMPRESSION_LEVEL option.  The <compression-level> should be between 0-9, with the default being 0.  The COMPRESSION option must be present when COMPRESSION_LEVEL is given.

Added in version 3.26: The <compression-level> of the Zstd algorithm can be set between 0-19.

NOTE:

With FORMAT set to raw, only one file will be compressed with the compression type specified by COMPRESSION.

The VERBOSE option enables verbose output for the archive operation.

To specify the modification time recorded in tarball entries, use the MTIME option.

file(ARCHIVE_EXTRACT INPUT <archive> [DESTINATION <dir>] [PATTERNS <patterns>...] [LIST_ONLY] [VERBOSE] [TOUCH])

Added in version 3.18.

Extracts or lists the content of the specified <archive>.

The directory where the content of the archive will be extracted to can be specified using the DESTINATION option.  If the directory does not exist, it will be created.  If DESTINATION is not given, the current binary directory will be used.

If required, you may select which files and directories to list or extract from the archive using the specified <patterns>.  Wildcards are supported.  If the PATTERNS option is not given, the entire archive will be listed or extracted.

LIST_ONLY will list the files in the archive rather than extract them.

Added in version 3.24: The TOUCH option gives extracted files a current local timestamp instead of extracting file timestamps from the archive.

With VERBOSE, the command will produce verbose output.

A short-hand signature is:

find_file (<VAR> name1 [path1 path2 ...])

The general signature is:

find_file (
          <VAR>
          name | NAMES name1 [name2 ...]
          [HINTS [path | ENV var]... ]
          [PATHS [path | ENV var]... ]
          [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
          [PATH_SUFFIXES suffix1 [suffix2 ...]]
          [VALIDATOR function]
          [DOC "cache documentation string"]
          [NO_CACHE]
          [REQUIRED]
          [NO_DEFAULT_PATH]
          [NO_PACKAGE_ROOT_PATH]
          [NO_CMAKE_PATH]
          [NO_CMAKE_ENVIRONMENT_PATH]
          [NO_SYSTEM_ENVIRONMENT_PATH]
          [NO_CMAKE_SYSTEM_PATH]
          [NO_CMAKE_INSTALL_PREFIX]
          [CMAKE_FIND_ROOT_PATH_BOTH |
           ONLY_CMAKE_FIND_ROOT_PATH |
           NO_CMAKE_FIND_ROOT_PATH]
         )

This command is used to find a full path to named file. A cache entry, or a normal variable if NO_CACHE is specified, named by <VAR> is created to store the result of this command. If the full path to a file is found the result is stored in the variable and the search will not be repeated unless the variable is cleared. If nothing is found, the result will be <VAR>-NOTFOUND.

Options include:

NAMES

Specify one or more possible names for the full path to a file.

When using this to specify names with and without a version suffix, we recommend specifying the unversioned name first so that locally-built packages can be found before those provided by distributions.

HINTS, PATHS

Specify directories to search in addition to the default locations. The ENV var sub-option reads paths from a system environment variable.

Changed in version 3.24: On Windows platform, it is possible to include registry queries as part of the directories, using a dedicated syntax. Such specifications will be ignored on all other platforms.

REGISTRY_VIEW

Added in version 3.24.

Specify which registry views must be queried. This option is only meaningful on Windows platforms and will be ignored on other ones. When not specified, the TARGET view is used when the CMP0134 policy is NEW. Refer to CMP0134 for the default view when the policy is OLD.

64

Query the 64-bit registry. On 32-bit Windows, it always returns the string /REGISTRY-NOTFOUND.

32

Query the 32-bit registry.

64_32

Query both views (64 and 32) and generate a path for each.

32_64

Query both views (32 and 64) and generate a path for each.

HOST

Query the registry matching the architecture of the host: 64 on 64-bit Windows and 32 on 32-bit Windows.

TARGET

Query the registry matching the architecture specified by the CMAKE_SIZEOF_VOID_P variable. If not defined, fall back to HOST view.

BOTH

Query both views (32 and 64). The order depends on the following rules: If the CMAKE_SIZEOF_VOID_P variable is defined, use the following view depending on the content of this variable:

• 8: 64_32
• 4: 32_64

If the CMAKE_SIZEOF_VOID_P variable is not defined, rely on the architecture of the host:

• 64-bit: 64_32
• 32-bit: 32

PATH_SUFFIXES

Specify additional subdirectories to check below each directory location otherwise considered.

VALIDATOR

Added in version 3.25.

Specify a function() to be called for each candidate item found (a macro() cannot be provided, that will result in an error). Two arguments will be passed to the validator function: the name of a result variable, and the absolute path to the candidate item.  The item will be accepted and the search will end unless the function sets the value in the result variable to false in the calling scope.  The result variable will hold a true value when the validator function is entered.

function(my_check validator_result_var item)
  if(NOT item MATCHES ...)
    set(${validator_result_var} FALSE PARENT_SCOPE)
  endif()
endfunction()

find_file (result NAMES ... VALIDATOR my_check)

Note that if a cached result is used, the search is skipped and any VALIDATOR is ignored.  The cached result is not required to pass the validation function.

DOC

Specify the documentation string for the <VAR> cache entry.

NO_CACHE

Added in version 3.21.

The result of the search will be stored in a normal variable rather than a cache entry.

NOTE:

If the variable is already set before the call (as a normal or cache variable) then the search will not occur.

WARNING:

This option should be used with caution because it can greatly increase the cost of repeated configure steps.

REQUIRED

Added in version 3.18.

Stop processing with an error message if nothing is found, otherwise the search will be attempted again the next time find_file is invoked with the same variable.

If NO_DEFAULT_PATH is specified, then no additional paths are added to the search. If NO_DEFAULT_PATH is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to find_package(<PackageName>), search prefixes unique to the current package being found.  See policy CMP0074.

   Added in version 3.12.

   Specifically, search paths specified by the following variables, in order:

   a.

   <PackageName>_ROOT CMake variable, where <PackageName> is the case-preserved package name.

   b.

   <PACKAGENAME>_ROOT CMake variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   c.

   <PackageName>_ROOT environment variable, where <PackageName> is the case-preserved package name.

   d.

   <PACKAGENAME>_ROOT environment variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   The package root variables are maintained as a stack, so if called from nested find modules or config packages, root paths from the parent's find module or config package will be searched after paths from the current module or package.  In other words, the search order would be <CurrentPackage>_ROOT, ENV{<CurrentPackage>_ROOT}, <ParentPackage>_ROOT, ENV{<ParentPackage>_ROOT}, etc. This can be skipped if NO_PACKAGE_ROOT_PATH is passed or by setting the CMAKE_FIND_USE_PACKAGE_ROOT_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in the <PackageName>_ROOT CMake variable and the <PackageName>_ROOT environment variable if called from within a find module loaded by find_package(<PackageName>)

2. Search paths specified in cmake-specific cache variables. These are intended to be used on the command line with a -DVAR=value. The values are interpreted as semicolon-separated lists. This can be skipped if NO_CMAKE_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_INCLUDE_PATH
   • CMAKE_FRAMEWORK_PATH

3. Search paths specified in cmake-specific environment variables. These are intended to be set in the user's shell configuration, and therefore use the host's native path separator (; on Windows and : on UNIX). This can be skipped if NO_CMAKE_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_INCLUDE_PATH
   • CMAKE_FRAMEWORK_PATH
4. Search the paths specified by the HINTS option. These should be paths computed by system introspection, such as a hint provided by the location of another item already found. Hard-coded guesses should be specified with the PATHS option.

5. Search the standard system environment variables. This can be skipped if NO_SYSTEM_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH to FALSE.

   • The directories in INCLUDE and PATH.

   On Windows hosts, CMake 3.3 through 3.27 searched additional paths: <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix>/[s]bin in PATH, and <entry>/include for other entries in PATH. This behavior was removed by CMake 3.28.

6. Search cmake variables defined in the Platform files for the current system.  The searching of CMAKE_INSTALL_PREFIX and CMAKE_STAGING_PREFIX can be skipped if NO_CMAKE_INSTALL_PREFIX is passed or by setting the CMAKE_FIND_USE_INSTALL_PREFIX to FALSE. All these locations can be skipped if NO_CMAKE_SYSTEM_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_SYSTEM_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in CMAKE_SYSTEM_PREFIX_PATH
   • CMAKE_SYSTEM_INCLUDE_PATH
   • CMAKE_SYSTEM_FRAMEWORK_PATH

   The platform paths that these variables contain are locations that typically include installed software. An example being /usr/local for UNIX based platforms.

7. Search the paths specified by the PATHS option or in the short-hand version of the command. These are typically hard-coded guesses.

The CMAKE_IGNORE_PATH, CMAKE_IGNORE_PREFIX_PATH, CMAKE_SYSTEM_IGNORE_PATH and CMAKE_SYSTEM_IGNORE_PREFIX_PATH variables can also cause some of the above locations to be ignored.

Added in version 3.16: Added CMAKE_FIND_USE_<CATEGORY>_PATH variables to globally disable various search locations.

On macOS the CMAKE_FIND_FRAMEWORK and CMAKE_FIND_APPBUNDLE variables determine the order of preference between Apple-style and unix-style package components.

The CMake variable CMAKE_FIND_ROOT_PATH specifies one or more directories to be prepended to all other search directories.  This effectively "re-roots" the entire search under given locations. Paths which are descendants of the CMAKE_STAGING_PREFIX are excluded from this re-rooting, because that variable is always a path on the host system. By default the CMAKE_FIND_ROOT_PATH is empty.

The CMAKE_SYSROOT variable can also be used to specify exactly one directory to use as a prefix.  Setting CMAKE_SYSROOT also has other effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to point to the root directory of the target environment and CMake will search there too.  By default at first the directories listed in CMAKE_FIND_ROOT_PATH are searched, then the CMAKE_SYSROOT directory is searched, and then the non-rooted directories will be searched.  The default behavior can be adjusted by setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE.  This behavior can be manually overridden on a per-call basis using options:

CMAKE_FIND_ROOT_PATH_BOTH

Search in the order described above.

NO_CMAKE_FIND_ROOT_PATH

Do not use the CMAKE_FIND_ROOT_PATH variable.

ONLY_CMAKE_FIND_ROOT_PATH

Search only the re-rooted directories and directories below CMAKE_STAGING_PREFIX.

The default search order is designed to be most-specific to least-specific for common use cases. Projects may override the order by simply calling the command multiple times and using the NO_* options:

find_file (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
find_file (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set and stored in the cache so that no call will search again.

A short-hand signature is:

find_library (<VAR> name1 [path1 path2 ...])

The general signature is:

find_library (
          <VAR>
          name | NAMES name1 [name2 ...] [NAMES_PER_DIR]
          [HINTS [path | ENV var]... ]
          [PATHS [path | ENV var]... ]
          [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
          [PATH_SUFFIXES suffix1 [suffix2 ...]]
          [VALIDATOR function]
          [DOC "cache documentation string"]
          [NO_CACHE]
          [REQUIRED]
          [NO_DEFAULT_PATH]
          [NO_PACKAGE_ROOT_PATH]
          [NO_CMAKE_PATH]
          [NO_CMAKE_ENVIRONMENT_PATH]
          [NO_SYSTEM_ENVIRONMENT_PATH]
          [NO_CMAKE_SYSTEM_PATH]
          [NO_CMAKE_INSTALL_PREFIX]
          [CMAKE_FIND_ROOT_PATH_BOTH |
           ONLY_CMAKE_FIND_ROOT_PATH |
           NO_CMAKE_FIND_ROOT_PATH]
         )

This command is used to find a library. A cache entry, or a normal variable if NO_CACHE is specified, named by <VAR> is created to store the result of this command. If the library is found the result is stored in the variable and the search will not be repeated unless the variable is cleared. If nothing is found, the result will be <VAR>-NOTFOUND.

Options include:

NAMES

Specify one or more possible names for the library.

When using this to specify names with and without a version suffix, we recommend specifying the unversioned name first so that locally-built packages can be found before those provided by distributions.

HINTS, PATHS

Specify directories to search in addition to the default locations. The ENV var sub-option reads paths from a system environment variable.

Changed in version 3.24: On Windows platform, it is possible to include registry queries as part of the directories, using a dedicated syntax. Such specifications will be ignored on all other platforms.

REGISTRY_VIEW

Added in version 3.24.

Specify which registry views must be queried. This option is only meaningful on Windows platforms and will be ignored on other ones. When not specified, the TARGET view is used when the CMP0134 policy is NEW. Refer to CMP0134 for the default view when the policy is OLD.

64

Query the 64-bit registry. On 32-bit Windows, it always returns the string /REGISTRY-NOTFOUND.

32

Query the 32-bit registry.

64_32

Query both views (64 and 32) and generate a path for each.

32_64

Query both views (32 and 64) and generate a path for each.

HOST

Query the registry matching the architecture of the host: 64 on 64-bit Windows and 32 on 32-bit Windows.

TARGET

Query the registry matching the architecture specified by the CMAKE_SIZEOF_VOID_P variable. If not defined, fall back to HOST view.

BOTH

Query both views (32 and 64). The order depends on the following rules: If the CMAKE_SIZEOF_VOID_P variable is defined, use the following view depending on the content of this variable:

• 8: 64_32
• 4: 32_64

If the CMAKE_SIZEOF_VOID_P variable is not defined, rely on the architecture of the host:

• 64-bit: 64_32
• 32-bit: 32

PATH_SUFFIXES

Specify additional subdirectories to check below each directory location otherwise considered.

VALIDATOR

Added in version 3.25.

Specify a function() to be called for each candidate item found (a macro() cannot be provided, that will result in an error). Two arguments will be passed to the validator function: the name of a result variable, and the absolute path to the candidate item.  The item will be accepted and the search will end unless the function sets the value in the result variable to false in the calling scope.  The result variable will hold a true value when the validator function is entered.

function(my_check validator_result_var item)
  if(NOT item MATCHES ...)
    set(${validator_result_var} FALSE PARENT_SCOPE)
  endif()
endfunction()

find_library (result NAMES ... VALIDATOR my_check)

Note that if a cached result is used, the search is skipped and any VALIDATOR is ignored.  The cached result is not required to pass the validation function.

DOC

Specify the documentation string for the <VAR> cache entry.

NO_CACHE

Added in version 3.21.

The result of the search will be stored in a normal variable rather than a cache entry.

NOTE:

If the variable is already set before the call (as a normal or cache variable) then the search will not occur.

WARNING:

This option should be used with caution because it can greatly increase the cost of repeated configure steps.

REQUIRED

Added in version 3.18.

Stop processing with an error message if nothing is found, otherwise the search will be attempted again the next time find_library is invoked with the same variable.

If NO_DEFAULT_PATH is specified, then no additional paths are added to the search. If NO_DEFAULT_PATH is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to find_package(<PackageName>), search prefixes unique to the current package being found.  See policy CMP0074.

   Added in version 3.12.

   Specifically, search paths specified by the following variables, in order:

   a.

   <PackageName>_ROOT CMake variable, where <PackageName> is the case-preserved package name.

   b.

   <PACKAGENAME>_ROOT CMake variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   c.

   <PackageName>_ROOT environment variable, where <PackageName> is the case-preserved package name.

   d.

   <PACKAGENAME>_ROOT environment variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   The package root variables are maintained as a stack, so if called from nested find modules or config packages, root paths from the parent's find module or config package will be searched after paths from the current module or package.  In other words, the search order would be <CurrentPackage>_ROOT, ENV{<CurrentPackage>_ROOT}, <ParentPackage>_ROOT, ENV{<ParentPackage>_ROOT}, etc. This can be skipped if NO_PACKAGE_ROOT_PATH is passed or by setting the CMAKE_FIND_USE_PACKAGE_ROOT_PATH to FALSE.

   • <prefix>/lib/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/lib for each <prefix> in the <PackageName>_ROOT CMake variable and the <PackageName>_ROOT environment variable if called from within a find module loaded by find_package(<PackageName>)

2. Search paths specified in cmake-specific cache variables. These are intended to be used on the command line with a -DVAR=value. The values are interpreted as semicolon-separated lists. This can be skipped if NO_CMAKE_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_PATH to FALSE.

   • <prefix>/lib/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/lib for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_LIBRARY_PATH
   • CMAKE_FRAMEWORK_PATH

3. Search paths specified in cmake-specific environment variables. These are intended to be set in the user's shell configuration, and therefore use the host's native path separator (; on Windows and : on UNIX). This can be skipped if NO_CMAKE_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH to FALSE.

   • <prefix>/lib/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/lib for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_LIBRARY_PATH
   • CMAKE_FRAMEWORK_PATH
4. Search the paths specified by the HINTS option. These should be paths computed by system introspection, such as a hint provided by the location of another item already found. Hard-coded guesses should be specified with the PATHS option.

5. Search the standard system environment variables. This can be skipped if NO_SYSTEM_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH to FALSE.

   • The directories in LIB and PATH.

   On Windows hosts, CMake 3.3 through 3.27 searched additional paths: <prefix>/lib/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/lib for each <prefix>/[s]bin in PATH, and <entry>/lib for other entries in PATH. This behavior was removed by CMake 3.28.

6. Search cmake variables defined in the Platform files for the current system.  The searching of CMAKE_INSTALL_PREFIX and CMAKE_STAGING_PREFIX can be skipped if NO_CMAKE_INSTALL_PREFIX is passed or by setting the CMAKE_FIND_USE_INSTALL_PREFIX to FALSE. All these locations can be skipped if NO_CMAKE_SYSTEM_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_SYSTEM_PATH to FALSE.

   • <prefix>/lib/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/lib for each <prefix> in CMAKE_SYSTEM_PREFIX_PATH
   • CMAKE_SYSTEM_LIBRARY_PATH
   • CMAKE_SYSTEM_FRAMEWORK_PATH

   The platform paths that these variables contain are locations that typically include installed software. An example being /usr/local for UNIX based platforms.

7. Search the paths specified by the PATHS option or in the short-hand version of the command. These are typically hard-coded guesses.

The CMAKE_IGNORE_PATH, CMAKE_IGNORE_PREFIX_PATH, CMAKE_SYSTEM_IGNORE_PATH and CMAKE_SYSTEM_IGNORE_PREFIX_PATH variables can also cause some of the above locations to be ignored.

Added in version 3.16: Added CMAKE_FIND_USE_<CATEGORY>_PATH variables to globally disable various search locations.

On macOS the CMAKE_FIND_FRAMEWORK and CMAKE_FIND_APPBUNDLE variables determine the order of preference between Apple-style and unix-style package components.

The CMake variable CMAKE_FIND_ROOT_PATH specifies one or more directories to be prepended to all other search directories.  This effectively "re-roots" the entire search under given locations. Paths which are descendants of the CMAKE_STAGING_PREFIX are excluded from this re-rooting, because that variable is always a path on the host system. By default the CMAKE_FIND_ROOT_PATH is empty.

The CMAKE_SYSROOT variable can also be used to specify exactly one directory to use as a prefix.  Setting CMAKE_SYSROOT also has other effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to point to the root directory of the target environment and CMake will search there too.  By default at first the directories listed in CMAKE_FIND_ROOT_PATH are searched, then the CMAKE_SYSROOT directory is searched, and then the non-rooted directories will be searched.  The default behavior can be adjusted by setting CMAKE_FIND_ROOT_PATH_MODE_LIBRARY.  This behavior can be manually overridden on a per-call basis using options:

CMAKE_FIND_ROOT_PATH_BOTH

Search in the order described above.

NO_CMAKE_FIND_ROOT_PATH

Do not use the CMAKE_FIND_ROOT_PATH variable.

ONLY_CMAKE_FIND_ROOT_PATH

Search only the re-rooted directories and directories below CMAKE_STAGING_PREFIX.

The default search order is designed to be most-specific to least-specific for common use cases. Projects may override the order by simply calling the command multiple times and using the NO_* options:

find_library (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
find_library (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set and stored in the cache so that no call will search again.

When more than one value is given to the NAMES option this command by default will consider one name at a time and search every directory for it.  The NAMES_PER_DIR option tells this command to consider one directory at a time and search for all names in it.

Each library name given to the NAMES option is first considered as a library file name and then considered with platform-specific prefixes (e.g. lib) and suffixes (e.g. .so).  Therefore one may specify library file names such as libfoo.a directly. This can be used to locate static libraries on UNIX-like systems.

If the library found is a framework, then <VAR> will be set to the full path to the framework <fullPath>/A.framework.  When a full path to a framework is used as a library, CMake will use a -framework A, and a -F<fullPath> to link the framework to the target.

Added in version 3.28: The library found can now be a .xcframework folder.

If the CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX variable is set all search paths will be tested as normal, with the suffix appended, and with all matches of lib/ replaced with lib${CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX}/.  This variable overrides the FIND_LIBRARY_USE_LIB32_PATHS, FIND_LIBRARY_USE_LIBX32_PATHS, and FIND_LIBRARY_USE_LIB64_PATHS global properties.

If the FIND_LIBRARY_USE_LIB32_PATHS global property is set all search paths will be tested as normal, with 32/ appended, and with all matches of lib/ replaced with lib32/.  This property is automatically set for the platforms that are known to need it if at least one of the languages supported by the project() command is enabled.

If the FIND_LIBRARY_USE_LIBX32_PATHS global property is set all search paths will be tested as normal, with x32/ appended, and with all matches of lib/ replaced with libx32/.  This property is automatically set for the platforms that are known to need it if at least one of the languages supported by the project() command is enabled.

If the FIND_LIBRARY_USE_LIB64_PATHS global property is set all search paths will be tested as normal, with 64/ appended, and with all matches of lib/ replaced with lib64/.  This property is automatically set for the platforms that are known to need it if at least one of the languages supported by the project() command is enabled.

NOTE:

The Using Dependencies Guide provides a high-level introduction to this general topic. It provides a broader overview of where the find_package() command fits into the bigger picture, including its relationship to the FetchContent module. The guide is recommended pre-reading before moving on to the details below.

Find a package (usually provided by something external to the project), and load its package-specific details.  Calls to this command can also be intercepted by dependency providers.

The command has a few modes by which it searches for packages:

Module mode

In this mode, CMake searches for a file called Find<PackageName>.cmake, looking first in the locations listed in the CMAKE_MODULE_PATH, then among the Find Modules provided by the CMake installation. If the file is found, it is read and processed by CMake.  It is responsible for finding the package, checking the version, and producing any needed messages.  Some Find modules provide limited or no support for versioning; check the Find module's documentation.

The Find<PackageName>.cmake file is not typically provided by the package itself.  Rather, it is normally provided by something external to the package, such as the operating system, CMake itself, or even the project from which the find_package() command was called.  Being externally provided, Find Modules tend to be heuristic in nature and are susceptible to becoming out-of-date.  They typically search for certain libraries, files and other package artifacts.

Module mode is only supported by the basic command signature.

Config mode

In this mode, CMake searches for a file called <lowercasePackageName>-config.cmake or <PackageName>Config.cmake. It will also look for <lowercasePackageName>-config-version.cmake or <PackageName>ConfigVersion.cmake if version details were specified (see Config Mode Version Selection for an explanation of how these separate version files are used).

In config mode, the command can be given a list of names to search for as package names.  The locations where CMake searches for the config and version files is considerably more complicated than for Module mode (see Config Mode Search Procedure).

The config and version files are typically installed as part of the package, so they tend to be more reliable than Find modules.  They usually contain direct knowledge of the package contents, so no searching or heuristics are needed within the config or version files themselves.

Config mode is supported by both the basic and full command signatures.

FetchContent redirection mode

Added in version 3.24: A call to find_package() can be redirected internally to a package provided by the FetchContent module.  To the caller, the behavior will appear similar to Config mode, except that the search logic is by-passed and the component information is not used.  See FetchContent_Declare() and FetchContent_MakeAvailable() for further details.

When not redirected to a package provided by FetchContent, the command arguments determine whether Module or Config mode is used.  When the basic signature is used, the command searches in Module mode first. If the package is not found, the search falls back to Config mode. A user may set the CMAKE_FIND_PACKAGE_PREFER_CONFIG variable to true to reverse the priority and direct CMake to search using Config mode first before falling back to Module mode.  The basic signature can also be forced to use only Module mode with a MODULE keyword.  If the full signature is used, the command only searches in Config mode.

Where possible, user code should generally look for packages using the basic signature, since that allows the package to be found with any mode. Project maintainers wishing to provide a config package should understand the bigger picture, as explained in Full Signature and all subsequent sections on this page.

find_package(<PackageName> [version] [EXACT] [QUIET] [MODULE]
             [REQUIRED] [[COMPONENTS] [components...]]
             [OPTIONAL_COMPONENTS components...]
             [REGISTRY_VIEW  (64|32|64_32|32_64|HOST|TARGET|BOTH)]
             [GLOBAL]
             [NO_POLICY_SCOPE]
             [BYPASS_PROVIDER])

The basic signature is supported by both Module and Config modes. The MODULE keyword implies that only Module mode can be used to find the package, with no fallback to Config mode.

Regardless of the mode used, a <PackageName>_FOUND variable will be set to indicate whether the package was found.  When the package is found, package-specific information may be provided through other variables and Imported Targets documented by the package itself.  The QUIET option disables informational messages, including those indicating that the package cannot be found if it is not REQUIRED.  The REQUIRED option stops processing with an error message if the package cannot be found.

A package-specific list of required components may be listed after the COMPONENTS keyword.  If any of these components are not able to be satisfied, the package overall is considered to be not found.  If the REQUIRED option is also present, this is treated as a fatal error, otherwise execution still continues.  As a form of shorthand, if the REQUIRED option is present, the COMPONENTS keyword can be omitted and the required components can be listed directly after REQUIRED.

Additional optional components may be listed after OPTIONAL_COMPONENTS.  If these cannot be satisfied, the package overall can still be considered found, as long as all required components are satisfied.

The set of available components and their meaning are defined by the target package.  Formally, it is up to the target package how to interpret the component information given to it, but it should follow the expectations stated above.  For calls where no components are specified, there is no single expected behavior and target packages should clearly define what occurs in such cases.  Common arrangements include assuming it should find all components, no components or some well-defined subset of the available components.

Added in version 3.24: The REGISTRY_VIEW keyword specifies which registry views should be queried. This keyword is only meaningful on Windows platforms and will be ignored on all others. Formally, it is up to the target package how to interpret the registry view information given to it.

Added in version 3.24: Specifying the GLOBAL keyword will promote all imported targets to a global scope in the importing project. Alternatively, this functionality can be enabled by setting the CMAKE_FIND_PACKAGE_TARGETS_GLOBAL variable.

The [version] argument requests a version with which the package found should be compatible. There are two possible forms in which it may be specified:

• A single version with the format major[.minor[.patch[.tweak]]], where each component is a numeric value.
• A version range with the format versionMin...[<]versionMax where versionMin and versionMax have the same format and constraints on components being integers as the single version.  By default, both end points are included.  By specifying <, the upper end point will be excluded. Version ranges are only supported with CMake 3.19 or later.

The EXACT option requests that the version be matched exactly. This option is incompatible with the specification of a version range.

If no [version] and/or component list is given to a recursive invocation inside a find-module, the corresponding arguments are forwarded automatically from the outer call (including the EXACT flag for [version]).  Version support is currently provided only on a package-by-package basis (see the Version Selection section below). When a version range is specified but the package is only designed to expect a single version, the package will ignore the upper end point of the range and only take the single version at the lower end of the range into account.

See the cmake_policy() command documentation for discussion of the NO_POLICY_SCOPE option.

Added in version 3.24: The BYPASS_PROVIDER keyword is only allowed when find_package() is being called by a dependency provider. It can be used by providers to call the built-in find_package() implementation directly and prevent that call from being re-routed back to itself.  Future versions of CMake may detect attempts to use this keyword from places other than a dependency provider and halt with a fatal error.

find_package(<PackageName> [version] [EXACT] [QUIET]
             [REQUIRED] [[COMPONENTS] [components...]]
             [OPTIONAL_COMPONENTS components...]
             [CONFIG|NO_MODULE]
             [GLOBAL]
             [NO_POLICY_SCOPE]
             [BYPASS_PROVIDER]
             [NAMES name1 [name2 ...]]
             [CONFIGS config1 [config2 ...]]
             [HINTS path1 [path2 ... ]]
             [PATHS path1 [path2 ... ]]
             [REGISTRY_VIEW  (64|32|64_32|32_64|HOST|TARGET|BOTH)]
             [PATH_SUFFIXES suffix1 [suffix2 ...]]
             [NO_DEFAULT_PATH]
             [NO_PACKAGE_ROOT_PATH]
             [NO_CMAKE_PATH]
             [NO_CMAKE_ENVIRONMENT_PATH]
             [NO_SYSTEM_ENVIRONMENT_PATH]
             [NO_CMAKE_PACKAGE_REGISTRY]
             [NO_CMAKE_BUILDS_PATH] # Deprecated; does nothing.
             [NO_CMAKE_SYSTEM_PATH]
             [NO_CMAKE_INSTALL_PREFIX]
             [NO_CMAKE_SYSTEM_PACKAGE_REGISTRY]
             [CMAKE_FIND_ROOT_PATH_BOTH |
              ONLY_CMAKE_FIND_ROOT_PATH |
              NO_CMAKE_FIND_ROOT_PATH])

The CONFIG option, the synonymous NO_MODULE option, or the use of options not specified in the basic signature all enforce pure Config mode.  In pure Config mode, the command skips Module mode search and proceeds at once with Config mode search.

Config mode search attempts to locate a configuration file provided by the package to be found.  A cache entry called <PackageName>_DIR is created to hold the directory containing the file.  By default, the command searches for a package with the name <PackageName>.  If the NAMES option is given, the names following it are used instead of <PackageName>.  The names are also considered when determining whether to redirect the call to a package provided by FetchContent.

The command searches for a file called <PackageName>Config.cmake or <lowercasePackageName>-config.cmake for each name specified. A replacement set of possible configuration file names may be given using the CONFIGS option.  The Config Mode Search Procedure is specified below. Once found, any version constraint is checked, and if satisfied, the configuration file is read and processed by CMake. Since the file is provided by the package it already knows the location of package contents.  The full path to the configuration file is stored in the cmake variable <PackageName>_CONFIG.

All configuration files which have been considered by CMake while searching for the package with an appropriate version are stored in the <PackageName>_CONSIDERED_CONFIGS variable, and the associated versions in the <PackageName>_CONSIDERED_VERSIONS variable.

If the package configuration file cannot be found CMake will generate an error describing the problem unless the QUIET argument is specified.  If REQUIRED is specified and the package is not found a fatal error is generated and the configure step stops executing.  If <PackageName>_DIR has been set to a directory not containing a configuration file CMake will ignore it and search from scratch.

Package maintainers providing CMake package configuration files are encouraged to name and install them such that the Config Mode Search Procedure outlined below will find them without requiring use of additional options.

NOTE:

When Config mode is used, this search procedure is applied regardless of whether the full or basic signature was given.

Added in version 3.24: All calls to find_package() (even in Module mode) first look for a config package file in the CMAKE_FIND_PACKAGE_REDIRECTS_DIR directory. The FetchContent module, or even the project itself, may write files to that location to redirect find_package() calls to content already provided by the project.  If no config package file is found in that location, the search proceeds with the logic described below.

CMake constructs a set of possible installation prefixes for the package.  Under each prefix several directories are searched for a configuration file.  The tables below show the directories searched. Each entry is meant for installation trees following Windows (W), UNIX (U), or Apple (A) conventions:

[1]

Added in version 3.25.

On systems supporting macOS FRAMEWORK and BUNDLE, the following directories are searched for Frameworks or Application Bundles containing a configuration file:

Entry	Convention
<prefix>/<name>.framework/Resources/	A
<prefix>/<name>.framework/Resources/CMake/	A
<prefix>/<name>.framework/Versions/*/Resources/	A
<prefix>/<name>.framework/Versions/*/Resources/CMake/	A
<prefix>/<name>.app/Contents/Resources/	A
<prefix>/<name>.app/Contents/Resources/CMake/	A

In all cases the <name> is treated as case-insensitive and corresponds to any of the names specified (<PackageName> or names given by NAMES).

If at least one compiled language has been enabled, the architecture-specific lib/<arch> and lib* directories may be searched based on the compiler's target architecture, in the following order:

lib/<arch>

Searched if the CMAKE_LIBRARY_ARCHITECTURE variable is set.

lib64

Searched on 64 bit platforms (CMAKE_SIZEOF_VOID_P is 8) and the FIND_LIBRARY_USE_LIB64_PATHS property is set to TRUE.

lib32

Searched on 32 bit platforms (CMAKE_SIZEOF_VOID_P is 4) and the FIND_LIBRARY_USE_LIB32_PATHS property is set to TRUE.

libx32

Searched on platforms using the x32 ABI if the FIND_LIBRARY_USE_LIBX32_PATHS property is set to TRUE.

lib

Always searched.

Changed in version 3.24: On Windows platform, it is possible to include registry queries as part of the directories specified through HINTS and PATHS keywords, using a dedicated syntax. Such specifications will be ignored on all other platforms.

Added in version 3.24: REGISTRY_VIEW can be specified to manage Windows registry queries specified as part of PATHS and HINTS.

Specify which registry views must be queried. This option is only meaningful on Windows platforms and will be ignored on other ones. When not specified, the TARGET view is used when the CMP0134 policy is NEW. Refer to CMP0134 for the default view when the policy is OLD.

64

Query the 64-bit registry. On 32-bit Windows, it always returns the string /REGISTRY-NOTFOUND.

32

Query the 32-bit registry.

64_32

Query both views (64 and 32) and generate a path for each.

32_64

Query both views (32 and 64) and generate a path for each.

HOST

Query the registry matching the architecture of the host: 64 on 64-bit Windows and 32 on 32-bit Windows.

TARGET

Query the registry matching the architecture specified by the CMAKE_SIZEOF_VOID_P variable. If not defined, fall back to HOST view.

BOTH

Query both views (32 and 64). The order depends on the following rules: If the CMAKE_SIZEOF_VOID_P variable is defined, use the following view depending on the content of this variable:

• 8: 64_32
• 4: 32_64

If the CMAKE_SIZEOF_VOID_P variable is not defined, rely on the architecture of the host:

• 64-bit: 64_32
• 32-bit: 32

If PATH_SUFFIXES is specified, the suffixes are appended to each (W) or (U) directory entry one-by-one.

This set of directories is intended to work in cooperation with projects that provide configuration files in their installation trees. Directories above marked with (W) are intended for installations on Windows where the prefix may point at the top of an application's installation directory.  Those marked with (U) are intended for installations on UNIX platforms where the prefix is shared by multiple packages.  This is merely a convention, so all (W) and (U) directories are still searched on all platforms.  Directories marked with (A) are intended for installations on Apple platforms.  The CMAKE_FIND_FRAMEWORK and CMAKE_FIND_APPBUNDLE variables determine the order of preference.

The set of installation prefixes is constructed using the following steps.  If NO_DEFAULT_PATH is specified all NO_* options are enabled.

1. Search prefixes unique to the current <PackageName> being found. See policy CMP0074.

   Added in version 3.12.

   Specifically, search prefixes specified by the following variables, in order:

   a.

   <PackageName>_ROOT CMake variable, where <PackageName> is the case-preserved package name.

   b.

   <PACKAGENAME>_ROOT CMake variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   c.

   <PackageName>_ROOT environment variable, where <PackageName> is the case-preserved package name.

   d.

   <PACKAGENAME>_ROOT environment variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   The package root variables are maintained as a stack so if called from within a find module, root paths from the parent's find module will also be searched after paths for the current package. This can be skipped if NO_PACKAGE_ROOT_PATH is passed or by setting the CMAKE_FIND_USE_PACKAGE_ROOT_PATH to FALSE.

2. Search paths specified in cmake-specific cache variables.  These are intended to be used on the command line with a -DVAR=VALUE. The values are interpreted as semicolon-separated lists. This can be skipped if NO_CMAKE_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_PATH to FALSE:
3. Search paths specified in cmake-specific environment variables. These are intended to be set in the user's shell configuration, and therefore use the host's native path separator (; on Windows and : on UNIX). This can be skipped if NO_CMAKE_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH to FALSE:
4. Search paths specified by the HINTS option.  These should be paths computed by system introspection, such as a hint provided by the location of another item already found.  Hard-coded guesses should be specified with the PATHS option.
5. Search the standard system environment variables.  This can be skipped if NO_SYSTEM_ENVIRONMENT_PATH is passed  or by setting the CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH to FALSE. Path entries ending in /bin or /sbin are automatically converted to their parent directories:

6. Search paths stored in the CMake User Package Registry. This can be skipped if NO_CMAKE_PACKAGE_REGISTRY is passed or by setting the variable CMAKE_FIND_USE_PACKAGE_REGISTRY to FALSE or the deprecated variable CMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY to TRUE.

   See the cmake-packages(7) manual for details on the user package registry.

7. Search cmake variables defined in the Platform files for the current system. The searching of CMAKE_INSTALL_PREFIX and CMAKE_STAGING_PREFIX can be skipped if NO_CMAKE_INSTALL_PREFIX is passed or by setting the CMAKE_FIND_USE_INSTALL_PREFIX to FALSE. All these locations can be skipped if NO_CMAKE_SYSTEM_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_SYSTEM_PATH to FALSE:

   • CMAKE_SYSTEM_PREFIX_PATH
   • CMAKE_SYSTEM_FRAMEWORK_PATH
   • CMAKE_SYSTEM_APPBUNDLE_PATH

   The platform paths that these variables contain are locations that typically include installed software. An example being /usr/local for UNIX based platforms.

8. Search paths stored in the CMake System Package Registry. This can be skipped if NO_CMAKE_SYSTEM_PACKAGE_REGISTRY is passed or by setting the CMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY variable to FALSE or the deprecated variable CMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY to TRUE.

   See the cmake-packages(7) manual for details on the system package registry.

9. Search paths specified by the PATHS option.  These are typically hard-coded guesses.

• PATH
• <PackageName>_DIR
• CMAKE_PREFIX_PATH
• CMAKE_FRAMEWORK_PATH
• CMAKE_APPBUNDLE_PATH
• CMAKE_PREFIX_PATH
• CMAKE_FRAMEWORK_PATH
• CMAKE_APPBUNDLE_PATH

The CMAKE_IGNORE_PATH, CMAKE_IGNORE_PREFIX_PATH, CMAKE_SYSTEM_IGNORE_PATH and CMAKE_SYSTEM_IGNORE_PREFIX_PATH variables can also cause some of the above locations to be ignored.

Added in version 3.16: Added the CMAKE_FIND_USE_<CATEGORY> variables to globally disable various search locations.

The CMake variable CMAKE_FIND_ROOT_PATH specifies one or more directories to be prepended to all other search directories.  This effectively "re-roots" the entire search under given locations. Paths which are descendants of the CMAKE_STAGING_PREFIX are excluded from this re-rooting, because that variable is always a path on the host system. By default the CMAKE_FIND_ROOT_PATH is empty.

The CMAKE_SYSROOT variable can also be used to specify exactly one directory to use as a prefix.  Setting CMAKE_SYSROOT also has other effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to point to the root directory of the target environment and CMake will search there too.  By default at first the directories listed in CMAKE_FIND_ROOT_PATH are searched, then the CMAKE_SYSROOT directory is searched, and then the non-rooted directories will be searched.  The default behavior can be adjusted by setting CMAKE_FIND_ROOT_PATH_MODE_PACKAGE.  This behavior can be manually overridden on a per-call basis using options:

CMAKE_FIND_ROOT_PATH_BOTH

Search in the order described above.

NO_CMAKE_FIND_ROOT_PATH

Do not use the CMAKE_FIND_ROOT_PATH variable.

ONLY_CMAKE_FIND_ROOT_PATH

Search only the re-rooted directories and directories below CMAKE_STAGING_PREFIX.

The default search order is designed to be most-specific to least-specific for common use cases. Projects may override the order by simply calling the command multiple times and using the NO_* options:

find_package (<PackageName> PATHS paths... NO_DEFAULT_PATH)
find_package (<PackageName>)

Once one of the calls succeeds the result variable will be set and stored in the cache so that no call will search again.

By default the value stored in the result variable will be the path at which the file is found.  The CMAKE_FIND_PACKAGE_RESOLVE_SYMLINKS variable may be set to TRUE before calling find_package in order to resolve symbolic links and store the real path to the file.

Every non-REQUIRED find_package call can be disabled or made REQUIRED:

• Setting the CMAKE_DISABLE_FIND_PACKAGE_<PackageName> variable to TRUE disables the package.  This also disables redirection to a package provided by FetchContent.
• Setting the CMAKE_REQUIRE_FIND_PACKAGE_<PackageName> variable to TRUE makes the package REQUIRED.

Setting both variables to TRUE simultaneously is an error.

NOTE:

When Config mode is used, this version selection process is applied regardless of whether the full or basic signature was given.

When the [version] argument is given, Config mode will only find a version of the package that claims compatibility with the requested version (see format specification). If the EXACT option is given, only a version of the package claiming an exact match of the requested version may be found.  CMake does not establish any convention for the meaning of version numbers.  Package version numbers are checked by "version" files provided by the packages themselves or by FetchContent.  For a candidate package configuration file <config-file>.cmake the corresponding version file is located next to it and named either <config-file>-version.cmake or <config-file>Version.cmake.  If no such version file is available then the configuration file is assumed to not be compatible with any requested version.  A basic version file containing generic version matching code can be created using the CMakePackageConfigHelpers module.  When a version file is found it is loaded to check the requested version number.  The version file is loaded in a nested scope in which the following variables have been defined:

PACKAGE_FIND_NAME

The <PackageName>

PACKAGE_FIND_VERSION

Full requested version string

PACKAGE_FIND_VERSION_MAJOR

Major version if requested, else 0

PACKAGE_FIND_VERSION_MINOR

Minor version if requested, else 0

PACKAGE_FIND_VERSION_PATCH

Patch version if requested, else 0

PACKAGE_FIND_VERSION_TWEAK

Tweak version if requested, else 0

PACKAGE_FIND_VERSION_COUNT

Number of version components, 0 to 4

When a version range is specified, the above version variables will hold values based on the lower end of the version range.  This is to preserve compatibility with packages that have not been implemented to expect version ranges.  In addition, the version range will be described by the following variables:

PACKAGE_FIND_VERSION_RANGE

Full requested version range string

PACKAGE_FIND_VERSION_RANGE_MIN

This specifies whether the lower end point of the version range should be included or excluded.  Currently, the only supported value for this variable is INCLUDE.

PACKAGE_FIND_VERSION_RANGE_MAX

This specifies whether the upper end point of the version range should be included or excluded.  The supported values for this variable are INCLUDE and EXCLUDE.

PACKAGE_FIND_VERSION_MIN

Full requested version string of the lower end point of the range

PACKAGE_FIND_VERSION_MIN_MAJOR

Major version of the lower end point if requested, else 0

PACKAGE_FIND_VERSION_MIN_MINOR

Minor version of the lower end point if requested, else 0

PACKAGE_FIND_VERSION_MIN_PATCH

Patch version of the lower end point if requested, else 0

PACKAGE_FIND_VERSION_MIN_TWEAK

Tweak version of the lower end point if requested, else 0

PACKAGE_FIND_VERSION_MIN_COUNT

Number of version components of the lower end point, 0 to 4

PACKAGE_FIND_VERSION_MAX

Full requested version string of the upper end point of the range

PACKAGE_FIND_VERSION_MAX_MAJOR

Major version of the upper end point if requested, else 0

PACKAGE_FIND_VERSION_MAX_MINOR

Minor version of the upper end point if requested, else 0

PACKAGE_FIND_VERSION_MAX_PATCH

Patch version of the upper end point if requested, else 0

PACKAGE_FIND_VERSION_MAX_TWEAK

Tweak version of the upper end point if requested, else 0

PACKAGE_FIND_VERSION_MAX_COUNT

Number of version components of the upper end point, 0 to 4

Regardless of whether a single version or a version range is specified, the variable PACKAGE_FIND_VERSION_COMPLETE will be defined and will hold the full requested version string as specified.

The version file checks whether it satisfies the requested version and sets these variables:

PACKAGE_VERSION

Full provided version string

PACKAGE_VERSION_EXACT

True if version is exact match

PACKAGE_VERSION_COMPATIBLE

True if version is compatible

PACKAGE_VERSION_UNSUITABLE

True if unsuitable as any version

These variables are checked by the find_package command to determine whether the configuration file provides an acceptable version.  They are not available after the find_package call returns.  If the version is acceptable the following variables are set:

<PackageName>_VERSION

Full provided version string

<PackageName>_VERSION_MAJOR

Major version if provided, else 0

<PackageName>_VERSION_MINOR

Minor version if provided, else 0

<PackageName>_VERSION_PATCH

Patch version if provided, else 0

<PackageName>_VERSION_TWEAK

Tweak version if provided, else 0

<PackageName>_VERSION_COUNT

Number of version components, 0 to 4

and the corresponding package configuration file is loaded. When multiple package configuration files are available whose version files claim compatibility with the version requested it is unspecified which one is chosen: unless the variable CMAKE_FIND_PACKAGE_SORT_ORDER is set no attempt is made to choose a highest or closest version number.

To control the order in which find_package checks for compatibility use the two variables CMAKE_FIND_PACKAGE_SORT_ORDER and CMAKE_FIND_PACKAGE_SORT_DIRECTION. For instance in order to select the highest version one can set

SET(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
SET(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)

before calling find_package.

When loading a find module or package configuration file find_package defines variables to provide information about the call arguments (and restores their original state before returning):

CMAKE_FIND_PACKAGE_NAME

The <PackageName> which is searched for

<PackageName>_FIND_REQUIRED

True if REQUIRED option was given

<PackageName>_FIND_QUIETLY

True if QUIET option was given

<PackageName>_FIND_REGISTRY_VIEW

The requested view if REGISTRY_VIEW option was given

<PackageName>_FIND_VERSION

Full requested version string

<PackageName>_FIND_VERSION_MAJOR

Major version if requested, else 0

<PackageName>_FIND_VERSION_MINOR

Minor version if requested, else 0

<PackageName>_FIND_VERSION_PATCH

Patch version if requested, else 0

<PackageName>_FIND_VERSION_TWEAK

Tweak version if requested, else 0

<PackageName>_FIND_VERSION_COUNT

Number of version components, 0 to 4

<PackageName>_FIND_VERSION_EXACT

True if EXACT option was given

<PackageName>_FIND_COMPONENTS

List of specified components (required and optional)

<PackageName>_FIND_REQUIRED_<c>

True if component <c> is required, false if component <c> is optional

When a version range is specified, the above version variables will hold values based on the lower end of the version range.  This is to preserve compatibility with packages that have not been implemented to expect version ranges.  In addition, the version range will be described by the following variables:

<PackageName>_FIND_VERSION_RANGE

Full requested version range string

<PackageName>_FIND_VERSION_RANGE_MIN

This specifies whether the lower end point of the version range is included or excluded.  Currently, INCLUDE is the only supported value.

<PackageName>_FIND_VERSION_RANGE_MAX

This specifies whether the upper end point of the version range is included or excluded.  The possible values for this variable are INCLUDE or EXCLUDE.

<PackageName>_FIND_VERSION_MIN

Full requested version string of the lower end point of the range

<PackageName>_FIND_VERSION_MIN_MAJOR

Major version of the lower end point if requested, else 0

<PackageName>_FIND_VERSION_MIN_MINOR

Minor version of the lower end point if requested, else 0

<PackageName>_FIND_VERSION_MIN_PATCH

Patch version of the lower end point if requested, else 0

<PackageName>_FIND_VERSION_MIN_TWEAK

Tweak version of the lower end point if requested, else 0

<PackageName>_FIND_VERSION_MIN_COUNT

Number of version components of the lower end point, 0 to 4

<PackageName>_FIND_VERSION_MAX

Full requested version string of the upper end point of the range

<PackageName>_FIND_VERSION_MAX_MAJOR

Major version of the upper end point if requested, else 0

<PackageName>_FIND_VERSION_MAX_MINOR

Minor version of the upper end point if requested, else 0

<PackageName>_FIND_VERSION_MAX_PATCH

Patch version of the upper end point if requested, else 0

<PackageName>_FIND_VERSION_MAX_TWEAK

Tweak version of the upper end point if requested, else 0

<PackageName>_FIND_VERSION_MAX_COUNT

Number of version components of the upper end point, 0 to 4

Regardless of whether a single version or a version range is specified, the variable <PackageName>_FIND_VERSION_COMPLETE will be defined and will hold the full requested version string as specified.

In Module mode the loaded find module is responsible to honor the request detailed by these variables; see the find module for details. In Config mode find_package handles REQUIRED, QUIET, and [version] options automatically but leaves it to the package configuration file to handle components in a way that makes sense for the package.  The package configuration file may set <PackageName>_FOUND to false to tell find_package that component requirements are not satisfied.

A short-hand signature is:

find_path (<VAR> name1 [path1 path2 ...])

The general signature is:

find_path (
          <VAR>
          name | NAMES name1 [name2 ...]
          [HINTS [path | ENV var]... ]
          [PATHS [path | ENV var]... ]
          [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
          [PATH_SUFFIXES suffix1 [suffix2 ...]]
          [VALIDATOR function]
          [DOC "cache documentation string"]
          [NO_CACHE]
          [REQUIRED]
          [NO_DEFAULT_PATH]
          [NO_PACKAGE_ROOT_PATH]
          [NO_CMAKE_PATH]
          [NO_CMAKE_ENVIRONMENT_PATH]
          [NO_SYSTEM_ENVIRONMENT_PATH]
          [NO_CMAKE_SYSTEM_PATH]
          [NO_CMAKE_INSTALL_PREFIX]
          [CMAKE_FIND_ROOT_PATH_BOTH |
           ONLY_CMAKE_FIND_ROOT_PATH |
           NO_CMAKE_FIND_ROOT_PATH]
         )

This command is used to find a directory containing the named file. A cache entry, or a normal variable if NO_CACHE is specified, named by <VAR> is created to store the result of this command. If the file in a directory is found the result is stored in the variable and the search will not be repeated unless the variable is cleared. If nothing is found, the result will be <VAR>-NOTFOUND.

Options include:

NAMES

Specify one or more possible names for the file in a directory.

When using this to specify names with and without a version suffix, we recommend specifying the unversioned name first so that locally-built packages can be found before those provided by distributions.

HINTS, PATHS

Specify directories to search in addition to the default locations. The ENV var sub-option reads paths from a system environment variable.

Changed in version 3.24: On Windows platform, it is possible to include registry queries as part of the directories, using a dedicated syntax. Such specifications will be ignored on all other platforms.

REGISTRY_VIEW

Added in version 3.24.

Specify which registry views must be queried. This option is only meaningful on Windows platforms and will be ignored on other ones. When not specified, the TARGET view is used when the CMP0134 policy is NEW. Refer to CMP0134 for the default view when the policy is OLD.

64

Query the 64-bit registry. On 32-bit Windows, it always returns the string /REGISTRY-NOTFOUND.

32

Query the 32-bit registry.

64_32

Query both views (64 and 32) and generate a path for each.

32_64

Query both views (32 and 64) and generate a path for each.

HOST

Query the registry matching the architecture of the host: 64 on 64-bit Windows and 32 on 32-bit Windows.

TARGET

Query the registry matching the architecture specified by the CMAKE_SIZEOF_VOID_P variable. If not defined, fall back to HOST view.

BOTH

Query both views (32 and 64). The order depends on the following rules: If the CMAKE_SIZEOF_VOID_P variable is defined, use the following view depending on the content of this variable:

• 8: 64_32
• 4: 32_64

If the CMAKE_SIZEOF_VOID_P variable is not defined, rely on the architecture of the host:

• 64-bit: 64_32
• 32-bit: 32

PATH_SUFFIXES

Specify additional subdirectories to check below each directory location otherwise considered.

VALIDATOR

Added in version 3.25.

Specify a function() to be called for each candidate item found (a macro() cannot be provided, that will result in an error). Two arguments will be passed to the validator function: the name of a result variable, and the absolute path to the candidate item.  The item will be accepted and the search will end unless the function sets the value in the result variable to false in the calling scope.  The result variable will hold a true value when the validator function is entered.

function(my_check validator_result_var item)
  if(NOT item MATCHES ...)
    set(${validator_result_var} FALSE PARENT_SCOPE)
  endif()
endfunction()

find_path (result NAMES ... VALIDATOR my_check)

Note that if a cached result is used, the search is skipped and any VALIDATOR is ignored.  The cached result is not required to pass the validation function.

DOC

Specify the documentation string for the <VAR> cache entry.

NO_CACHE

Added in version 3.21.

The result of the search will be stored in a normal variable rather than a cache entry.

NOTE:

If the variable is already set before the call (as a normal or cache variable) then the search will not occur.

WARNING:

This option should be used with caution because it can greatly increase the cost of repeated configure steps.

REQUIRED

Added in version 3.18.

Stop processing with an error message if nothing is found, otherwise the search will be attempted again the next time find_path is invoked with the same variable.

If NO_DEFAULT_PATH is specified, then no additional paths are added to the search. If NO_DEFAULT_PATH is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to find_package(<PackageName>), search prefixes unique to the current package being found.  See policy CMP0074.

   Added in version 3.12.

   Specifically, search paths specified by the following variables, in order:

   a.

   <PackageName>_ROOT CMake variable, where <PackageName> is the case-preserved package name.

   b.

   <PACKAGENAME>_ROOT CMake variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   c.

   <PackageName>_ROOT environment variable, where <PackageName> is the case-preserved package name.

   d.

   <PACKAGENAME>_ROOT environment variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   The package root variables are maintained as a stack, so if called from nested find modules or config packages, root paths from the parent's find module or config package will be searched after paths from the current module or package.  In other words, the search order would be <CurrentPackage>_ROOT, ENV{<CurrentPackage>_ROOT}, <ParentPackage>_ROOT, ENV{<ParentPackage>_ROOT}, etc. This can be skipped if NO_PACKAGE_ROOT_PATH is passed or by setting the CMAKE_FIND_USE_PACKAGE_ROOT_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in the <PackageName>_ROOT CMake variable and the <PackageName>_ROOT environment variable if called from within a find module loaded by find_package(<PackageName>)

2. Search paths specified in cmake-specific cache variables. These are intended to be used on the command line with a -DVAR=value. The values are interpreted as semicolon-separated lists. This can be skipped if NO_CMAKE_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_INCLUDE_PATH
   • CMAKE_FRAMEWORK_PATH

3. Search paths specified in cmake-specific environment variables. These are intended to be set in the user's shell configuration, and therefore use the host's native path separator (; on Windows and : on UNIX). This can be skipped if NO_CMAKE_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_INCLUDE_PATH
   • CMAKE_FRAMEWORK_PATH
4. Search the paths specified by the HINTS option. These should be paths computed by system introspection, such as a hint provided by the location of another item already found. Hard-coded guesses should be specified with the PATHS option.

5. Search the standard system environment variables. This can be skipped if NO_SYSTEM_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH to FALSE.

   • The directories in INCLUDE and PATH.

   On Windows hosts, CMake 3.3 through 3.27 searched additional paths: <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix>/[s]bin in PATH, and <entry>/include for other entries in PATH. This behavior was removed by CMake 3.28.

6. Search cmake variables defined in the Platform files for the current system.  The searching of CMAKE_INSTALL_PREFIX and CMAKE_STAGING_PREFIX can be skipped if NO_CMAKE_INSTALL_PREFIX is passed or by setting the CMAKE_FIND_USE_INSTALL_PREFIX to FALSE. All these locations can be skipped if NO_CMAKE_SYSTEM_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_SYSTEM_PATH to FALSE.

   • <prefix>/include/<arch> if CMAKE_LIBRARY_ARCHITECTURE is set, and <prefix>/include for each <prefix> in CMAKE_SYSTEM_PREFIX_PATH
   • CMAKE_SYSTEM_INCLUDE_PATH
   • CMAKE_SYSTEM_FRAMEWORK_PATH

   The platform paths that these variables contain are locations that typically include installed software. An example being /usr/local for UNIX based platforms.

7. Search the paths specified by the PATHS option or in the short-hand version of the command. These are typically hard-coded guesses.

The CMAKE_IGNORE_PATH, CMAKE_IGNORE_PREFIX_PATH, CMAKE_SYSTEM_IGNORE_PATH and CMAKE_SYSTEM_IGNORE_PREFIX_PATH variables can also cause some of the above locations to be ignored.

Added in version 3.16: Added CMAKE_FIND_USE_<CATEGORY>_PATH variables to globally disable various search locations.

On macOS the CMAKE_FIND_FRAMEWORK and CMAKE_FIND_APPBUNDLE variables determine the order of preference between Apple-style and unix-style package components.

The CMake variable CMAKE_FIND_ROOT_PATH specifies one or more directories to be prepended to all other search directories.  This effectively "re-roots" the entire search under given locations. Paths which are descendants of the CMAKE_STAGING_PREFIX are excluded from this re-rooting, because that variable is always a path on the host system. By default the CMAKE_FIND_ROOT_PATH is empty.

The CMAKE_SYSROOT variable can also be used to specify exactly one directory to use as a prefix.  Setting CMAKE_SYSROOT also has other effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to point to the root directory of the target environment and CMake will search there too.  By default at first the directories listed in CMAKE_FIND_ROOT_PATH are searched, then the CMAKE_SYSROOT directory is searched, and then the non-rooted directories will be searched.  The default behavior can be adjusted by setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE.  This behavior can be manually overridden on a per-call basis using options:

CMAKE_FIND_ROOT_PATH_BOTH

Search in the order described above.

NO_CMAKE_FIND_ROOT_PATH

Do not use the CMAKE_FIND_ROOT_PATH variable.

ONLY_CMAKE_FIND_ROOT_PATH

Search only the re-rooted directories and directories below CMAKE_STAGING_PREFIX.

The default search order is designed to be most-specific to least-specific for common use cases. Projects may override the order by simply calling the command multiple times and using the NO_* options:

find_path (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
find_path (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set and stored in the cache so that no call will search again.

When searching for frameworks, if the file is specified as A/b.h, then the framework search will look for A.framework/Headers/b.h.  If that is found the path will be set to the path to the framework.  CMake will convert this to the correct -F option to include the file.

A short-hand signature is:

find_program (<VAR> name1 [path1 path2 ...])

The general signature is:

find_program (
          <VAR>
          name | NAMES name1 [name2 ...] [NAMES_PER_DIR]
          [HINTS [path | ENV var]... ]
          [PATHS [path | ENV var]... ]
          [REGISTRY_VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
          [PATH_SUFFIXES suffix1 [suffix2 ...]]
          [VALIDATOR function]
          [DOC "cache documentation string"]
          [NO_CACHE]
          [REQUIRED]
          [NO_DEFAULT_PATH]
          [NO_PACKAGE_ROOT_PATH]
          [NO_CMAKE_PATH]
          [NO_CMAKE_ENVIRONMENT_PATH]
          [NO_SYSTEM_ENVIRONMENT_PATH]
          [NO_CMAKE_SYSTEM_PATH]
          [NO_CMAKE_INSTALL_PREFIX]
          [CMAKE_FIND_ROOT_PATH_BOTH |
           ONLY_CMAKE_FIND_ROOT_PATH |
           NO_CMAKE_FIND_ROOT_PATH]
         )

This command is used to find a program. A cache entry, or a normal variable if NO_CACHE is specified, named by <VAR> is created to store the result of this command. If the program is found the result is stored in the variable and the search will not be repeated unless the variable is cleared. If nothing is found, the result will be <VAR>-NOTFOUND.

Options include:

NAMES

Specify one or more possible names for the program.

When using this to specify names with and without a version suffix, we recommend specifying the unversioned name first so that locally-built packages can be found before those provided by distributions.

HINTS, PATHS

Specify directories to search in addition to the default locations. The ENV var sub-option reads paths from a system environment variable.

Changed in version 3.24: On Windows platform, it is possible to include registry queries as part of the directories, using a dedicated syntax. Such specifications will be ignored on all other platforms.

REGISTRY_VIEW

Added in version 3.24.

Specify which registry views must be queried. This option is only meaningful on Windows platforms and will be ignored on other ones. When not specified, the BOTH view is used when the CMP0134 policy is NEW. Refer to CMP0134 for the default view when the policy is OLD.

64

Query the 64-bit registry. On 32-bit Windows, it always returns the string /REGISTRY-NOTFOUND.

32

Query the 32-bit registry.

64_32

Query both views (64 and 32) and generate a path for each.

32_64

Query both views (32 and 64) and generate a path for each.

HOST

Query the registry matching the architecture of the host: 64 on 64-bit Windows and 32 on 32-bit Windows.

TARGET

Query the registry matching the architecture specified by the CMAKE_SIZEOF_VOID_P variable. If not defined, fall back to HOST view.

BOTH

Query both views (32 and 64). The order depends on the following rules: If the CMAKE_SIZEOF_VOID_P variable is defined, use the following view depending on the content of this variable:

• 8: 64_32
• 4: 32_64

If the CMAKE_SIZEOF_VOID_P variable is not defined, rely on the architecture of the host:

• 64-bit: 64_32
• 32-bit: 32

PATH_SUFFIXES

Specify additional subdirectories to check below each directory location otherwise considered.

VALIDATOR

Added in version 3.25.

Specify a function() to be called for each candidate item found (a macro() cannot be provided, that will result in an error). Two arguments will be passed to the validator function: the name of a result variable, and the absolute path to the candidate item.  The item will be accepted and the search will end unless the function sets the value in the result variable to false in the calling scope.  The result variable will hold a true value when the validator function is entered.

function(my_check validator_result_var item)
  if(NOT item MATCHES ...)
    set(${validator_result_var} FALSE PARENT_SCOPE)
  endif()
endfunction()

find_program (result NAMES ... VALIDATOR my_check)

Note that if a cached result is used, the search is skipped and any VALIDATOR is ignored.  The cached result is not required to pass the validation function.

DOC

Specify the documentation string for the <VAR> cache entry.

NO_CACHE

Added in version 3.21.

The result of the search will be stored in a normal variable rather than a cache entry.

NOTE:

If the variable is already set before the call (as a normal or cache variable) then the search will not occur.

WARNING:

This option should be used with caution because it can greatly increase the cost of repeated configure steps.

REQUIRED

Added in version 3.18.

Stop processing with an error message if nothing is found, otherwise the search will be attempted again the next time find_program is invoked with the same variable.

If NO_DEFAULT_PATH is specified, then no additional paths are added to the search. If NO_DEFAULT_PATH is not specified, the search process is as follows:

1. If called from within a find module or any other script loaded by a call to find_package(<PackageName>), search prefixes unique to the current package being found.  See policy CMP0074.

   Added in version 3.12.

   Specifically, search paths specified by the following variables, in order:

   a.

   <PackageName>_ROOT CMake variable, where <PackageName> is the case-preserved package name.

   b.

   <PACKAGENAME>_ROOT CMake variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   c.

   <PackageName>_ROOT environment variable, where <PackageName> is the case-preserved package name.

   d.

   <PACKAGENAME>_ROOT environment variable, where <PACKAGENAME> is the upper-cased package name. See policy CMP0144.

   Added in version 3.27.

   The package root variables are maintained as a stack, so if called from nested find modules or config packages, root paths from the parent's find module or config package will be searched after paths from the current module or package.  In other words, the search order would be <CurrentPackage>_ROOT, ENV{<CurrentPackage>_ROOT}, <ParentPackage>_ROOT, ENV{<ParentPackage>_ROOT}, etc. This can be skipped if NO_PACKAGE_ROOT_PATH is passed or by setting the CMAKE_FIND_USE_PACKAGE_ROOT_PATH to FALSE.

   • <prefix>/[s]bin for each <prefix> in the <PackageName>_ROOT CMake variable and the <PackageName>_ROOT environment variable if called from within a find module loaded by find_package(<PackageName>)

2. Search paths specified in cmake-specific cache variables. These are intended to be used on the command line with a -DVAR=value. The values are interpreted as semicolon-separated lists. This can be skipped if NO_CMAKE_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_PATH to FALSE.

   • <prefix>/[s]bin for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_PROGRAM_PATH
   • CMAKE_APPBUNDLE_PATH

3. Search paths specified in cmake-specific environment variables. These are intended to be set in the user's shell configuration, and therefore use the host's native path separator (; on Windows and : on UNIX). This can be skipped if NO_CMAKE_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH to FALSE.

   • <prefix>/[s]bin for each <prefix> in CMAKE_PREFIX_PATH
   • CMAKE_PROGRAM_PATH
   • CMAKE_APPBUNDLE_PATH
4. Search the paths specified by the HINTS option. These should be paths computed by system introspection, such as a hint provided by the location of another item already found. Hard-coded guesses should be specified with the PATHS option.

5. Search the standard system environment variables. This can be skipped if NO_SYSTEM_ENVIRONMENT_PATH is passed or by setting the CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH to FALSE.

   • The directories in PATH itself.

6. Search cmake variables defined in the Platform files for the current system.  The searching of CMAKE_INSTALL_PREFIX and CMAKE_STAGING_PREFIX can be skipped if NO_CMAKE_INSTALL_PREFIX is passed or by setting the CMAKE_FIND_USE_INSTALL_PREFIX to FALSE. All these locations can be skipped if NO_CMAKE_SYSTEM_PATH is passed or by setting the CMAKE_FIND_USE_CMAKE_SYSTEM_PATH to FALSE.

   • <prefix>/[s]bin for each <prefix> in CMAKE_SYSTEM_PREFIX_PATH
   • CMAKE_SYSTEM_PROGRAM_PATH
   • CMAKE_SYSTEM_APPBUNDLE_PATH

   The platform paths that these variables contain are locations that typically include installed software. An example being /usr/local for UNIX based platforms.

7. Search the paths specified by the PATHS option or in the short-hand version of the command. These are typically hard-coded guesses.

The CMAKE_IGNORE_PATH, CMAKE_IGNORE_PREFIX_PATH, CMAKE_SYSTEM_IGNORE_PATH and CMAKE_SYSTEM_IGNORE_PREFIX_PATH variables can also cause some of the above locations to be ignored.

Added in version 3.16: Added CMAKE_FIND_USE_<CATEGORY>_PATH variables to globally disable various search locations.

On macOS the CMAKE_FIND_FRAMEWORK and CMAKE_FIND_APPBUNDLE variables determine the order of preference between Apple-style and unix-style package components.

The CMake variable CMAKE_FIND_ROOT_PATH specifies one or more directories to be prepended to all other search directories.  This effectively "re-roots" the entire search under given locations. Paths which are descendants of the CMAKE_STAGING_PREFIX are excluded from this re-rooting, because that variable is always a path on the host system. By default the CMAKE_FIND_ROOT_PATH is empty.

The CMAKE_SYSROOT variable can also be used to specify exactly one directory to use as a prefix.  Setting CMAKE_SYSROOT also has other effects.  See the documentation for that variable for more.

These variables are especially useful when cross-compiling to point to the root directory of the target environment and CMake will search there too.  By default at first the directories listed in CMAKE_FIND_ROOT_PATH are searched, then the CMAKE_SYSROOT directory is searched, and then the non-rooted directories will be searched.  The default behavior can be adjusted by setting CMAKE_FIND_ROOT_PATH_MODE_PROGRAM.  This behavior can be manually overridden on a per-call basis using options:

CMAKE_FIND_ROOT_PATH_BOTH

Search in the order described above.

NO_CMAKE_FIND_ROOT_PATH

Do not use the CMAKE_FIND_ROOT_PATH variable.

ONLY_CMAKE_FIND_ROOT_PATH

Search only the re-rooted directories and directories below CMAKE_STAGING_PREFIX.

The default search order is designed to be most-specific to least-specific for common use cases. Projects may override the order by simply calling the command multiple times and using the NO_* options:

find_program (<VAR> NAMES name PATHS paths... NO_DEFAULT_PATH)
find_program (<VAR> NAMES name)

Once one of the calls succeeds the result variable will be set and stored in the cache so that no call will search again.

When more than one value is given to the NAMES option this command by default will consider one name at a time and search every directory for it.  The NAMES_PER_DIR option tells this command to consider one directory at a time and search for all names in it.

Evaluate a group of commands for each value in a list.

foreach(<loop_var> <items>)
  <commands>
endforeach()

where <items> is a list of items that are separated by semicolon or whitespace. All commands between foreach and the matching endforeach are recorded without being invoked.  Once the endforeach is evaluated, the recorded list of commands is invoked once for each item in <items>. At the beginning of each iteration the variable <loop_var> will be set to the value of the current item.

The scope of <loop_var> is restricted to the loop scope. See policy CMP0124 for details.

The commands break() and continue() provide means to escape from the normal control flow.

Per legacy, the endforeach() command admits an optional <loop_var> argument. If used, it must be a verbatim repeat of the argument of the opening foreach command.

foreach(<loop_var> RANGE <stop>)

In this variant, foreach iterates over the numbers 0, 1, ... up to (and including) the nonnegative integer <stop>.

foreach(<loop_var> RANGE <start> <stop> [<step>])

In this variant, foreach iterates over the numbers from <start> up to at most <stop> in steps of <step>. If <step> is not specified, then the step size is 1. The three arguments <start> <stop> <step> must all be nonnegative integers, and <stop> must not be smaller than <start>; otherwise you enter the danger zone of undocumented behavior that may change in future releases.

foreach(<loop_var> IN [LISTS [<lists>]] [ITEMS [<items>]])

In this variant, <lists> is a whitespace or semicolon separated list of list-valued variables. The foreach command iterates over each item in each given list. The <items> following the ITEMS keyword are processed as in the first variant of the foreach command. The forms LISTS A and ITEMS ${A} are equivalent.

The following example shows how the LISTS option is processed:

set(A 0;1)
set(B 2 3)
set(C "4 5")
set(D 6;7 8)
set(E "")
foreach(X IN LISTS A B C D E)
    message(STATUS "X=${X}")
endforeach()

yields:

-- X=0
-- X=1
-- X=2
-- X=3
-- X=4 5
-- X=6
-- X=7
-- X=8

foreach(<loop_var>... IN ZIP_LISTS <lists>)

Added in version 3.17.

In this variant, <lists> is a whitespace or semicolon separated list of list-valued variables. The foreach command iterates over each list simultaneously setting the iteration variables as follows:

• if the only loop_var given, then it sets a series of loop_var_N variables to the current item from the corresponding list;
• if multiple variable names passed, their count should match the lists variables count;

• if any of the lists are shorter, the corresponding iteration variable is not defined for the current iteration.

  list(APPEND English one two three four)
  list(APPEND Bahasa satu dua tiga)
  
  foreach(num IN ZIP_LISTS English Bahasa)
      message(STATUS "num_0=${num_0}, num_1=${num_1}")
  endforeach()
  
  foreach(en ba IN ZIP_LISTS English Bahasa)
      message(STATUS "en=${en}, ba=${ba}")
  endforeach()

yields:

-- num_0=one, num_1=satu
-- num_0=two, num_1=dua
-- num_0=three, num_1=tiga
-- num_0=four, num_1=
-- en=one, ba=satu
-- en=two, ba=dua
-- en=three, ba=tiga
-- en=four, ba=

• break()
• continue()
• endforeach()
• while()

Start recording a function for later invocation as a command.

function(<name> [<arg1> ...])
  <commands>
endfunction()

Defines a function named <name> that takes arguments named <arg1>, ...  The <commands> in the function definition are recorded; they are not executed until the function is invoked.

Per legacy, the endfunction() command admits an optional <name> argument. If used, it must be a verbatim repeat of the argument of the opening function command.

A function opens a new scope: see set(var PARENT_SCOPE) for details.

See the cmake_policy() command documentation for the behavior of policies inside functions.

See the macro() command documentation for differences between CMake functions and macros.

The function invocation is case-insensitive. A function defined as

function(foo)
  <commands>
endfunction()

can be invoked through any of

foo()
Foo()
FOO()
cmake_language(CALL foo)

and so on. However, it is strongly recommended to stay with the case chosen in the function definition. Typically functions use all-lowercase names.

Added in version 3.18: The cmake_language(CALL ...) command can also be used to invoke the function.

When the function is invoked, the recorded <commands> are first modified by replacing formal parameters (${arg1}, ...) with the arguments passed, and then invoked as normal commands.

In addition to referencing the formal parameters you can reference the ARGC variable which will be set to the number of arguments passed into the function as well as ARGV0, ARGV1, ARGV2, ...  which will have the actual values of the arguments passed in.  This facilitates creating functions with optional arguments.

Furthermore, ARGV holds the list of all arguments given to the function and ARGN holds the list of arguments past the last expected argument.  Referencing to ARGV# arguments beyond ARGC have undefined behavior.  Checking that ARGC is greater than # is the only way to ensure that ARGV# was passed to the function as an extra argument.

• cmake_parse_arguments()
• endfunction()
• return()

Get a global property of the CMake instance.

get_cmake_property(<variable> <property>)

Gets a global property from the CMake instance.  The value of the <property> is stored in the specified <variable>. If the property is not found, <variable> will be set to NOTFOUND. See the cmake-properties(7) manual for available properties.

In addition to global properties, this command (for historical reasons) also supports the VARIABLES and MACROS directory properties.  It also supports a special COMPONENTS global property that lists the components given to the install() command.

• the get_property() command GLOBAL option

Get a property of DIRECTORY scope.

get_directory_property(<variable> [DIRECTORY <dir>] <prop-name>)

Stores a property of directory scope in the named <variable>.

The DIRECTORY argument specifies another directory from which to retrieve the property value instead of the current directory. Relative paths are treated as relative to the current source directory.  CMake must already know about the directory, either by having added it through a call to add_subdirectory() or being the top level directory.

Added in version 3.19: <dir> may reference a binary directory.

If the property is not defined for the nominated directory scope, an empty string is returned.  In the case of INHERITED properties, if the property is not found for the nominated directory scope, the search will chain to a parent scope as described for the define_property() command.

get_directory_property(<variable> [DIRECTORY <dir>]
                       DEFINITION <var-name>)

Get a variable definition from a directory.  This form is useful to get a variable definition from another directory.

• define_property()
• the more general get_property() command

Get a specific component of a full filename.

Changed in version 3.20: This command has been superseded by the cmake_path() command, except for REALPATH, which is now offered by file(REAL_PATH), and PROGRAM, now available in separate_arguments(PROGRAM).

Changed in version 3.24: The undocumented feature offering the capability to query the Windows registry is superseded by cmake_host_system_information(Query WINDOWS_REGISTRY) command.

get_filename_component(<var> <FileName> <mode> [CACHE])

Sets <var> to a component of <FileName>, where <mode> is one of:

DIRECTORY = Directory without file name
NAME      = File name without directory
EXT       = File name longest extension (.b.c from d/a.b.c)
NAME_WE   = File name with neither the directory nor the longest extension
LAST_EXT  = File name last extension (.c from d/a.b.c)
NAME_WLE  = File name with neither the directory nor the last extension
PATH      = Legacy alias for DIRECTORY (use for CMake <= 2.8.11)

Added in version 3.14: Added the LAST_EXT and NAME_WLE modes.

Paths are returned with forward slashes and have no trailing slashes. If the optional CACHE argument is specified, the result variable is added to the cache.

get_filename_component(<var> <FileName> <mode> [BASE_DIR <dir>] [CACHE])

Added in version 3.4.

Sets <var> to the absolute path of <FileName>, where <mode> is one of:

ABSOLUTE  = Full path to file
REALPATH  = Full path to existing file with symlinks resolved

If the provided <FileName> is a relative path, it is evaluated relative to the given base directory <dir>.  If no base directory is provided, the default base directory will be CMAKE_CURRENT_SOURCE_DIR.

Paths are returned with forward slashes and have no trailing slashes.  If the optional CACHE argument is specified, the result variable is added to the cache.

get_filename_component(<var> <FileName> PROGRAM [PROGRAM_ARGS <arg_var>] [CACHE])

The program in <FileName> will be found in the system search path or left as a full path.  If PROGRAM_ARGS is present with PROGRAM, then any command-line arguments present in the <FileName> string are split from the program name and stored in <arg_var>.  This is used to separate a program name from its arguments in a command line string.

• cmake_path()

Get a property.

get_property(<variable>
             <GLOBAL             |
              DIRECTORY [<dir>]  |
              TARGET    <target> |
              SOURCE    <source>
                        [DIRECTORY <dir> | TARGET_DIRECTORY <target>] |
              INSTALL   <file>   |
              TEST      <test>
                        [DIRECTORY <dir>] |
              CACHE     <entry>  |
              VARIABLE           >
             PROPERTY <name>
             [SET | DEFINED | BRIEF_DOCS | FULL_DOCS])

Gets one property from one object in a scope.

The first argument specifies the variable in which to store the result. The second argument determines the scope from which to get the property. It must be one of the following:

GLOBAL

Scope is unique and does not accept a name.

DIRECTORY

Scope defaults to the current directory but another directory (already processed by CMake) may be named by the full or relative path <dir>. Relative paths are treated as relative to the current source directory. See also the get_directory_property() command.

Added in version 3.19: <dir> may reference a binary directory.

TARGET

Scope must name one existing target. See also the get_target_property() command.

SOURCE

Scope must name one source file.  By default, the source file's property will be read from the current source directory's scope.

Added in version 3.18: Directory scope can be overridden with one of the following sub-options:

DIRECTORY <dir>

The source file property will be read from the <dir> directory's scope.  CMake must already know about the directory, either by having added it through a call to add_subdirectory() or <dir> being the top level directory. Relative paths are treated as relative to the current source directory.

Added in version 3.19: <dir> may reference a binary directory.

TARGET_DIRECTORY <target>

The source file property will be read from the directory scope in which <target> was created (<target> must therefore already exist).

See also the get_source_file_property() command.

INSTALL

Added in version 3.1.

Scope must name one installed file path.

TEST

Scope must name one existing test. See also the get_test_property() command.

Added in version 3.28: Directory scope can be overridden with the following sub-option:

DIRECTORY <dir>

The test property will be read from the <dir> directory's scope.  CMake must already know about the directory, either by having added it through a call to add_subdirectory() or <dir> being the top level directory. Relative paths are treated as relative to the current source directory. <dir> may reference a binary directory.

CACHE

Scope must name one cache entry.

VARIABLE

Scope is unique and does not accept a name.

The required PROPERTY option is immediately followed by the name of the property to get.  If the property is not set an empty value is returned, although some properties support inheriting from a parent scope if defined to behave that way (see define_property()).

If the SET option is given the variable is set to a boolean value indicating whether the property has been set.  If the DEFINED option is given the variable is set to a boolean value indicating whether the property has been defined such as with the define_property() command.

If BRIEF_DOCS or FULL_DOCS is given then the variable is set to a string containing documentation for the requested property.  If documentation is requested for a property that has not been defined NOTFOUND is returned.

NOTE:

• define_property()
• set_property()

Conditionally execute a group of commands.

if(<condition>)
  <commands>
elseif(<condition>) # optional block, can be repeated
  <commands>
else()              # optional block
  <commands>
endif()

Evaluates the condition argument of the if clause according to the Condition syntax described below. If the result is true, then the commands in the if block are executed. Otherwise, optional elseif blocks are processed in the same way. Finally, if no condition is true, commands in the optional else block are executed.

Per legacy, the else() and endif() commands admit an optional <condition> argument. If used, it must be a verbatim repeat of the argument of the opening if command.

The following syntax applies to the condition argument of the if, elseif and while() clauses.

Compound conditions are evaluated in the following order of precedence:

1. Parentheses.
2. Unary tests such as EXISTS, COMMAND, and DEFINED.
3. Binary tests such as EQUAL, LESS, LESS_EQUAL, GREATER, GREATER_EQUAL, STREQUAL, STRLESS, STRLESS_EQUAL, STRGREATER, STRGREATER_EQUAL, VERSION_EQUAL, VERSION_LESS, VERSION_LESS_EQUAL, VERSION_GREATER, VERSION_GREATER_EQUAL, PATH_EQUAL, and MATCHES.
4. Unary logical operator NOT.
5. Binary logical operators AND and OR, from left to right, without any short-circuit.

if(<constant>)

True if the constant is 1, ON, YES, TRUE, Y, or a non-zero number (including floating point numbers). False if the constant is 0, OFF, NO, FALSE, N, IGNORE, NOTFOUND, the empty string, or ends in the suffix -NOTFOUND.  Named boolean constants are case-insensitive.  If the argument is not one of these specific constants, it is treated as a variable or string (see Variable Expansion further below) and one of the following two forms applies.

if(<variable>)

True if given a variable that is defined to a value that is not a false constant.  False otherwise, including if the variable is undefined. Note that macro arguments are not variables. Environment Variables also cannot be tested this way, e.g. if(ENV{some_var}) will always evaluate to false.

if(<string>)

A quoted string always evaluates to false unless:

• The string's value is one of the true constants, or
• Policy CMP0054 is not set to NEW and the string's value happens to be a variable name that is affected by CMP0054's behavior.

if(NOT <condition>)

True if the condition is not true.

if(<cond1> AND <cond2>)

True if both conditions would be considered true individually.

if(<cond1> OR <cond2>)

True if either condition would be considered true individually.

if((condition) AND (condition OR (condition)))

The conditions inside the parenthesis are evaluated first and then the remaining condition is evaluated as in the other examples. Where there are nested parenthesis the innermost are evaluated as part of evaluating the condition that contains them.

if(COMMAND <command-name>)

True if the given name is a command, macro or function that can be invoked.

if(POLICY <policy-id>)

True if the given name is an existing policy (of the form CMP<NNNN>).

if(TARGET <target-name>)

True if the given name is an existing logical target name created by a call to the add_executable(), add_library(), or add_custom_target() command that has already been invoked (in any directory).

if(TEST <test-name>)

Added in version 3.3.

True if the given name is an existing test name created by the add_test() command.

if(DEFINED <name>|CACHE{<name>}|ENV{<name>})

True if a variable, cache variable or environment variable with given <name> is defined. The value of the variable does not matter. Note the following caveats:

• Macro arguments are not variables.
• It is not possible to test directly whether a <name> is a non-cache variable.  The expression if(DEFINED someName) will evaluate to true if either a cache or non-cache variable someName exists.  In comparison, the expression if(DEFINED CACHE{someName}) will only evaluate to true if a cache variable someName exists.  Both expressions need to be tested if you need to know whether a non-cache variable exists: if(DEFINED someName AND NOT DEFINED CACHE{someName}).

Added in version 3.14: Added support for CACHE{<name>} variables.

if(<variable|string> IN_LIST <variable>)

Added in version 3.3.

True if the given element is contained in the named list variable.

if(EXISTS <path-to-file-or-directory>)

True if the named file or directory exists and is readable.  Behavior is well-defined only for explicit full paths (a leading ~/ is not expanded as a home directory and is considered a relative path). Resolves symbolic links, i.e. if the named file or directory is a symbolic link, returns true if the target of the symbolic link exists.

False if the given path is an empty string.

if(<file1> IS_NEWER_THAN <file2>)

True if file1 is newer than file2 or if one of the two files doesn't exist.  Behavior is well-defined only for full paths.  If the file time stamps are exactly the same, an IS_NEWER_THAN comparison returns true, so that any dependent build operations will occur in the event of a tie.  This includes the case of passing the same file name for both file1 and file2.

if(IS_DIRECTORY <path>)

True if path is a directory.  Behavior is well-defined only for full paths.

False if the given path is an empty string.

if(IS_SYMLINK <path>)

True if the given path is a symbolic link.  Behavior is well-defined only for full paths.

if(IS_ABSOLUTE <path>)

True if the given path is an absolute path.  Note the following special cases:

• An empty path evaluates to false.
• On Windows hosts, any path that begins with a drive letter and colon (e.g. C:), a forward slash or a backslash will evaluate to true. This means a path like C:no\base\dir will evaluate to true, even though the non-drive part of the path is relative.
• On non-Windows hosts, any path that begins with a tilde (~) evaluates to true.

if(<variable|string> MATCHES <regex>)

True if the given string or variable's value matches the given regular expression.  See Regex Specification for regex format.

Added in version 3.9: () groups are captured in CMAKE_MATCH_<n> variables.

if(<variable|string> LESS <variable|string>)

True if the given string or variable's value parses as a real number (like a C double) and less than that on the right.

if(<variable|string> GREATER <variable|string>)

True if the given string or variable's value parses as a real number (like a C double) and greater than that on the right.

if(<variable|string> EQUAL <variable|string>)

True if the given string or variable's value parses as a real number (like a C double) and equal to that on the right.

if(<variable|string> LESS_EQUAL <variable|string>)

Added in version 3.7.

True if the given string or variable's value parses as a real number (like a C double) and less than or equal to that on the right.

if(<variable|string> GREATER_EQUAL <variable|string>)

Added in version 3.7.

True if the given string or variable's value parses as a real number (like a C double) and greater than or equal to that on the right.

if(<variable|string> STRLESS <variable|string>)

True if the given string or variable's value is lexicographically less than the string or variable on the right.

if(<variable|string> STRGREATER <variable|string>)

True if the given string or variable's value is lexicographically greater than the string or variable on the right.

if(<variable|string> STREQUAL <variable|string>)

True if the given string or variable's value is lexicographically equal to the string or variable on the right.

if(<variable|string> STRLESS_EQUAL <variable|string>)

Added in version 3.7.

True if the given string or variable's value is lexicographically less than or equal to the string or variable on the right.

if(<variable|string> STRGREATER_EQUAL <variable|string>)

Added in version 3.7.

True if the given string or variable's value is lexicographically greater than or equal to the string or variable on the right.

if(<variable|string> VERSION_LESS <variable|string>)

Component-wise integer version number comparison (version format is major[.minor[.patch[.tweak]]], omitted components are treated as zero). Any non-integer version component or non-integer trailing part of a version component effectively truncates the string at that point.

if(<variable|string> VERSION_GREATER <variable|string>)

Component-wise integer version number comparison (version format is major[.minor[.patch[.tweak]]], omitted components are treated as zero). Any non-integer version component or non-integer trailing part of a version component effectively truncates the string at that point.

if(<variable|string> VERSION_EQUAL <variable|string>)

Component-wise integer version number comparison (version format is major[.minor[.patch[.tweak]]], omitted components are treated as zero). Any non-integer version component or non-integer trailing part of a version component effectively truncates the string at that point.

if(<variable|string> VERSION_LESS_EQUAL <variable|string>)

Added in version 3.7.

Component-wise integer version number comparison (version format is major[.minor[.patch[.tweak]]], omitted components are treated as zero). Any non-integer version component or non-integer trailing part of a version component effectively truncates the string at that point.

if(<variable|string> VERSION_GREATER_EQUAL <variable|string>)

Added in version 3.7.

Component-wise integer version number comparison (version format is major[.minor[.patch[.tweak]]], omitted components are treated as zero). Any non-integer version component or non-integer trailing part of a version component effectively truncates the string at that point.

if(<variable|string> PATH_EQUAL <variable|string>)

Added in version 3.24.

Compares the two paths component-by-component.  Only if every component of both paths match will the two paths compare equal.  Multiple path separators are effectively collapsed into a single separator, but note that backslashes are not converted to forward slashes.  No other path normalization is performed.

Component-wise comparison is superior to string-based comparison due to the handling of multiple path separators.  In the following example, the expression evaluates to true using PATH_EQUAL, but false with STREQUAL:

# comparison is TRUE
if ("/a//b/c" PATH_EQUAL "/a/b/c")
   ...
endif()

# comparison is FALSE
if ("/a//b/c" STREQUAL "/a/b/c")
   ...
endif()

See cmake_path(COMPARE) for more details.

The if command was written very early in CMake's history, predating the ${} variable evaluation syntax, and for convenience evaluates variables named by its arguments as shown in the above signatures. Note that normal variable evaluation with ${} applies before the if command even receives the arguments.  Therefore code like

set(var1 OFF)
set(var2 "var1")
if(${var2})

appears to the if command as

if(var1)

and is evaluated according to the if(<variable>) case documented above.  The result is OFF which is false.  However, if we remove the ${} from the example then the command sees

if(var2)

which is true because var2 is defined to var1 which is not a false constant.

Automatic evaluation applies in the other cases whenever the above-documented condition syntax accepts <variable|string>:

• The left hand argument to MATCHES is first checked to see if it is a defined variable.  If so, the variable's value is used, otherwise the original value is used.
• If the left hand argument to MATCHES is missing it returns false without error
• Both left and right hand arguments to LESS, GREATER, EQUAL, LESS_EQUAL, and GREATER_EQUAL, are independently tested to see if they are defined variables.  If so, their defined values are used otherwise the original value is used.
• Both left and right hand arguments to STRLESS, STRGREATER, STREQUAL, STRLESS_EQUAL, and STRGREATER_EQUAL are independently tested to see if they are defined variables.  If so, their defined values are used otherwise the original value is used.
• Both left and right hand arguments to VERSION_LESS, VERSION_GREATER, VERSION_EQUAL, VERSION_LESS_EQUAL, and VERSION_GREATER_EQUAL are independently tested to see if they are defined variables.  If so, their defined values are used otherwise the original value is used.
• The right hand argument to NOT is tested to see if it is a boolean constant.  If so, the value is used, otherwise it is assumed to be a variable and it is dereferenced.
• The left and right hand arguments to AND and OR are independently tested to see if they are boolean constants.  If so, they are used as such, otherwise they are assumed to be variables and are dereferenced.

Changed in version 3.1: To prevent ambiguity, potential variable or keyword names can be specified in a Quoted Argument or a Bracket Argument. A quoted or bracketed variable or keyword will be interpreted as a string and not dereferenced or interpreted. See policy CMP0054.

There is no automatic evaluation for environment or cache Variable References.  Their values must be referenced as $ENV{<name>} or $CACHE{<name>} wherever the above-documented condition syntax accepts <variable|string>.

• else()
• elseif()
• endif()

Load and run CMake code from a file or module.

include(<file|module> [OPTIONAL] [RESULT_VARIABLE <var>]
                      [NO_POLICY_SCOPE])

Loads and runs CMake code from the file given.  Variable reads and writes access the scope of the caller (dynamic scoping).  If OPTIONAL is present, then no error is raised if the file does not exist.  If RESULT_VARIABLE is given the variable <var> will be set to the full filename which has been included or NOTFOUND if it failed.

If a module is specified instead of a file, the file with name <modulename>.cmake is searched first in CMAKE_MODULE_PATH, then in the CMake module directory.  There is one exception to this: if the file which calls include() is located itself in the CMake builtin module directory, then first the CMake builtin module directory is searched and CMAKE_MODULE_PATH afterwards.  See also policy CMP0017.

See the cmake_policy() command documentation for discussion of the NO_POLICY_SCOPE option.

Added in version 3.10.

Provides an include guard for the file currently being processed by CMake.

include_guard([DIRECTORY|GLOBAL])

Sets up an include guard for the current CMake file (see the CMAKE_CURRENT_LIST_FILE variable documentation).

CMake will end its processing of the current file at the location of the include_guard command if the current file has already been processed for the applicable scope (see below). This provides functionality similar to the include guards commonly used in source headers or to the #pragma once directive. If the current file has been processed previously for the applicable scope, the effect is as though return() had been called. Do not call this command from inside a function being defined within the current file.

An optional argument specifying the scope of the guard may be provided. Possible values for the option are:

DIRECTORY

The include guard applies within the current directory and below. The file will only be included once within this directory scope, but may be included again by other files outside of this directory (i.e. a parent directory or another directory not pulled in by add_subdirectory() or include() from the current file or its children).

GLOBAL

The include guard applies globally to the whole build. The current file will only be included once regardless of the scope.

If no arguments given, include_guard has the same scope as a variable, meaning that the include guard effect is isolated by the most recent function scope or current directory if no inner function scopes exist. In this case the command behavior is the same as:

if(__CURRENT_FILE_VAR__)
  return()
endif()
set(__CURRENT_FILE_VAR__ TRUE)

Operations on semicolon-separated lists.

Reading
  list(LENGTH <list> <out-var>)
  list(GET <list> <element index> [<index> ...] <out-var>)
  list(JOIN <list> <glue> <out-var>)
  list(SUBLIST <list> <begin> <length> <out-var>)

Search
  list(FIND <list> <value> <out-var>)

Modification
  list(APPEND <list> [<element>...])
  list(FILTER <list> {INCLUDE | EXCLUDE} REGEX <regex>)
  list(INSERT <list> <index> [<element>...])
  list(POP_BACK <list> [<out-var>...])
  list(POP_FRONT <list> [<out-var>...])
  list(PREPEND <list> [<element>...])
  list(REMOVE_ITEM <list> <value>...)
  list(REMOVE_AT <list> <index>...)
  list(REMOVE_DUPLICATES <list>)
  list(TRANSFORM <list> <ACTION> [...])

Ordering
  list(REVERSE <list>)
  list(SORT <list> [...])

The list subcommands APPEND, INSERT, FILTER, PREPEND, POP_BACK, POP_FRONT, REMOVE_AT, REMOVE_ITEM, REMOVE_DUPLICATES, REVERSE and SORT may create new values for the list within the current CMake variable scope.  Similar to the set() command, the list command creates new variable values in the current scope, even if the list itself is actually defined in a parent scope.  To propagate the results of these operations upwards, use set() with PARENT_SCOPE, set() with CACHE INTERNAL, or some other means of value propagation.

NOTE:

A list in cmake is a ; separated group of strings.  To create a list, the set() command can be used.  For example, set(var a b c d e) creates a list with a;b;c;d;e, and set(var "a b c d e") creates a string or a list with one item in it. (Note that macro arguments are not variables, and therefore cannot be used in LIST commands.)

Individual elements may not contain an unequal number of [ and ] characters, and may not end in a backslash (\). See semicolon-separated lists for details.

NOTE:

When specifying index values, if <element index> is 0 or greater, it is indexed from the beginning of the list, with 0 representing the first list element.  If <element index> is -1 or lesser, it is indexed from the end of the list, with -1 representing the last list element. Be careful when counting with negative indices: they do not start from 0.  -0 is equivalent to 0, the first list element.

list(LENGTH <list> <output variable>)

Returns the list's length.

list(GET <list> <element index> [<element index> ...] <output variable>)

Returns the list of elements specified by indices from the list.

list(JOIN <list> <glue> <output variable>)

Added in version 3.12.

Returns a string joining all list's elements using the glue string. To join multiple strings, which are not part of a list, use string(JOIN).

list(SUBLIST <list> <begin> <length> <output variable>)

Added in version 3.12.

Returns a sublist of the given list. If <length> is 0, an empty list will be returned. If <length> is -1 or the list is smaller than <begin>+<length> then the remaining elements of the list starting at <begin> will be returned.

list(FIND <list> <value> <output variable>)

Returns the index of the element specified in the list or -1 if it wasn't found.

list(APPEND <list> [<element> ...])

Appends elements to the list. If no variable named <list> exists in the current scope its value is treated as empty and the elements are appended to that empty list.

list(FILTER <list> <INCLUDE|EXCLUDE> REGEX <regular_expression>)

Added in version 3.6.

Includes or removes items from the list that match the mode's pattern. In REGEX mode, items will be matched against the given regular expression.

For more information on regular expressions look under string(REGEX).

list(INSERT <list> <element_index> <element> [<element> ...])

Inserts elements to the list to the specified index. It is an error to specify an out-of-range index. Valid indexes are 0 to N where N is the length of the list, inclusive. An empty list has length 0. If no variable named <list> exists in the current scope its value is treated as empty and the elements are inserted in that empty list.

list(POP_BACK <list> [<out-var>...])

Added in version 3.15.

If no variable name is given, removes exactly one element. Otherwise, with N variable names provided, assign the last N elements' values to the given variables and then remove the last N values from <list>.

list(POP_FRONT <list> [<out-var>...])

Added in version 3.15.

If no variable name is given, removes exactly one element. Otherwise, with N variable names provided, assign the first N elements' values to the given variables and then remove the first N values from <list>.

list(PREPEND <list> [<element> ...])

Added in version 3.15.

Insert elements to the 0th position in the list. If no variable named <list> exists in the current scope its value is treated as empty and the elements are prepended to that empty list.

list(REMOVE_ITEM <list> <value> [<value> ...])

Removes all instances of the given items from the list.

list(REMOVE_AT <list> <index> [<index> ...])

Removes items at given indices from the list.

list(REMOVE_DUPLICATES <list>)

Removes duplicated items in the list. The relative order of items is preserved, but if duplicates are encountered, only the first instance is preserved.

list(TRANSFORM <list> <ACTION> [<SELECTOR>] [OUTPUT_VARIABLE <output variable>])

Added in version 3.12.

Transforms the list by applying an <ACTION> to all or, by specifying a <SELECTOR>, to the selected elements of the list, storing the result in-place or in the specified output variable.

NOTE:

The TRANSFORM sub-command does not change the number of elements in the list. If a <SELECTOR> is specified, only some elements will be changed, the other ones will remain the same as before the transformation.

<ACTION> specifies the action to apply to the elements of the list. The actions have exactly the same semantics as sub-commands of the string() command.  <ACTION> must be one of the following:

APPEND, PREPEND

Append, prepend specified value to each element of the list.

list(TRANSFORM <list> (APPEND|PREPEND) <value> ...)

TOLOWER, TOUPPER

Convert each element of the list to lower, upper characters.

list(TRANSFORM <list> (TOLOWER|TOUPPER) ...)

STRIP

Remove leading and trailing spaces from each element of the list.

list(TRANSFORM <list> STRIP ...)

GENEX_STRIP

Strip any generator expressions from each element of the list.

list(TRANSFORM <list> GENEX_STRIP ...)

REPLACE:

Match the regular expression as many times as possible and substitute the replacement expression for the match for each element of the list (same semantic as string(REGEX REPLACE)).

list(TRANSFORM <list> REPLACE <regular_expression> <replace_expression> ...)

<SELECTOR> determines which elements of the list will be transformed. Only one type of selector can be specified at a time. When given, <SELECTOR> must be one of the following:

AT

Specify a list of indexes.

list(TRANSFORM <list> <ACTION> AT <index> [<index> ...] ...)

FOR

Specify a range with, optionally, an increment used to iterate over the range.

list(TRANSFORM <list> <ACTION> FOR <start> <stop> [<step>] ...)

REGEX

Specify a regular expression. Only elements matching the regular expression will be transformed.

list(TRANSFORM <list> <ACTION> REGEX <regular_expression> ...)

list(REVERSE <list>)

Reverses the contents of the list in-place.

list(SORT <list> [COMPARE <compare>] [CASE <case>] [ORDER <order>])

Sorts the list in-place alphabetically.

Added in version 3.13: Added the COMPARE, CASE, and ORDER options.

Added in version 3.18: Added the COMPARE NATURAL option.

Use the COMPARE keyword to select the comparison method for sorting. The <compare> option should be one of:

STRING

Sorts a list of strings alphabetically. This is the default behavior if the COMPARE option is not given.

FILE_BASENAME

Sorts a list of pathnames of files by their basenames.

NATURAL

Sorts a list of strings using natural order (see strverscmp(3) manual), i.e. such that contiguous digits are compared as whole numbers. For example: the following list 10.0 1.1 2.1 8.0 2.0 3.1 will be sorted as 1.1 2.0 2.1 3.1 8.0 10.0 if the NATURAL comparison is selected where it will be sorted as 1.1 10.0 2.0 2.1 3.1 8.0 with the STRING comparison.

Use the CASE keyword to select a case sensitive or case insensitive sort mode.  The <case> option should be one of:

SENSITIVE

List items are sorted in a case-sensitive manner. This is the default behavior if the CASE option is not given.

INSENSITIVE

List items are sorted case insensitively.  The order of items which differ only by upper/lowercase is not specified.

To control the sort order, the ORDER keyword can be given. The <order> option should be one of:

ASCENDING

Sorts the list in ascending order. This is the default behavior when the ORDER option is not given.

DESCENDING

Sorts the list in descending order.

Start recording a macro for later invocation as a command

macro(<name> [<arg1> ...])
  <commands>
endmacro()

Defines a macro named <name> that takes arguments named <arg1>, ... Commands listed after macro, but before the matching endmacro(), are not executed until the macro is invoked.

Per legacy, the endmacro() command admits an optional <name> argument. If used, it must be a verbatim repeat of the argument of the opening macro command.

See the cmake_policy() command documentation for the behavior of policies inside macros.

See the Macro vs Function section below for differences between CMake macros and functions.

The macro invocation is case-insensitive. A macro defined as

macro(foo)
  <commands>
endmacro()

can be invoked through any of

foo()
Foo()
FOO()
cmake_language(CALL foo)

and so on. However, it is strongly recommended to stay with the case chosen in the macro definition.  Typically macros use all-lowercase names.

Added in version 3.18: The cmake_language(CALL ...) command can also be used to invoke the macro.

When a macro is invoked, the commands recorded in the macro are first modified by replacing formal parameters (${arg1}, ...) with the arguments passed, and then invoked as normal commands.

In addition to referencing the formal parameters you can reference the values ${ARGC} which will be set to the number of arguments passed into the function as well as ${ARGV0}, ${ARGV1}, ${ARGV2}, ...  which will have the actual values of the arguments passed in. This facilitates creating macros with optional arguments.

Furthermore, ${ARGV} holds the list of all arguments given to the macro and ${ARGN} holds the list of arguments past the last expected argument. Referencing to ${ARGV#} arguments beyond ${ARGC} have undefined behavior. Checking that ${ARGC} is greater than # is the only way to ensure that ${ARGV#} was passed to the function as an extra argument.

The macro command is very similar to the function() command. Nonetheless, there are a few important differences.

In a function, ARGN, ARGC, ARGV and ARGV0, ARGV1, ... are true variables in the usual CMake sense.  In a macro, they are not, they are string replacements much like the C preprocessor would do with a macro.  This has a number of consequences, as explained in the Argument Caveats section below.

Another difference between macros and functions is the control flow. A function is executed by transferring control from the calling statement to the function body.  A macro is executed as if the macro body were pasted in place of the calling statement.  This has the consequence that a return() in a macro body does not just terminate execution of the macro; rather, control is returned from the scope of the macro call.  To avoid confusion, it is recommended to avoid return() in macros altogether.

Unlike a function, the CMAKE_CURRENT_FUNCTION, CMAKE_CURRENT_FUNCTION_LIST_DIR, CMAKE_CURRENT_FUNCTION_LIST_FILE, CMAKE_CURRENT_FUNCTION_LIST_LINE variables are not set for a macro.

Since ARGN, ARGC, ARGV, ARGV0 etc. are not variables, you will NOT be able to use commands like

if(ARGV1) # ARGV1 is not a variable
if(DEFINED ARGV2) # ARGV2 is not a variable
if(ARGC GREATER 2) # ARGC is not a variable
foreach(loop_var IN LISTS ARGN) # ARGN is not a variable

In the first case, you can use if(${ARGV1}).  In the second and third case, the proper way to check if an optional variable was passed to the macro is to use if(${ARGC} GREATER 2).  In the last case, you can use foreach(loop_var ${ARGN}) but this will skip empty arguments.  If you need to include them, you can use

set(list_var "${ARGN}")
foreach(loop_var IN LISTS list_var)

Note that if you have a variable with the same name in the scope from which the macro is called, using unreferenced names will use the existing variable instead of the arguments. For example:

macro(bar)
  foreach(arg IN LISTS ARGN)
    <commands>
  endforeach()
endmacro()

function(foo)
  bar(x y z)
endfunction()

foo(a b c)

Will loop over a;b;c and not over x;y;z as one might have expected. If you want true CMake variables and/or better CMake scope control you should look at the function command.

• cmake_parse_arguments()
• endmacro()

Mark cmake cached variables as advanced.

mark_as_advanced([CLEAR|FORCE] <var1> ...)

Sets the advanced/non-advanced state of the named cached variables.

An advanced variable will not be displayed in any of the cmake GUIs unless the show advanced option is on. In script mode, the advanced/non-advanced state has no effect.

If the keyword CLEAR is given then advanced variables are changed back to unadvanced. If the keyword FORCE is given then the variables are made advanced. If neither FORCE nor CLEAR is specified, new values will be marked as advanced, but if a variable already has an advanced/non-advanced state, it will not be changed.

Changed in version 3.17: Variables passed to this command which are not already in the cache are ignored. See policy CMP0102.

Evaluate a mathematical expression.

math(EXPR <variable> "<expression>" [OUTPUT_FORMAT <format>])

Evaluates a mathematical <expression> and sets <variable> to the resulting value.  The result of the expression must be representable as a 64-bit signed integer. Floating point inputs are invalid e.g. 1.1 * 10. Non-integer results e.g. 3 / 2 are truncated.

The mathematical expression must be given as a string (i.e. enclosed in double quotation marks). An example is "5 * (10 + 13)". Supported operators are +, -, *, /, %, |, &, ^, ~, <<, >>, and (...); they have the same meaning as in C code.

Added in version 3.13: Hexadecimal numbers are recognized when prefixed with 0x, as in C code.

Added in version 3.13: The result is formatted according to the option OUTPUT_FORMAT, where <format> is one of

HEXADECIMAL

Hexadecimal notation as in C code, i. e. starting with "0x".

DECIMAL

Decimal notation. Which is also used if no OUTPUT_FORMAT option is specified.

For example

math(EXPR value "100 * 0xA" OUTPUT_FORMAT DECIMAL)      # value is set to "1000"
math(EXPR value "100 * 0xA" OUTPUT_FORMAT HEXADECIMAL)  # value is set to "0x3e8"

Log a message.

General messages
  message([<mode>] "message text" ...)

Reporting checks
  message(<checkState> "message text" ...)

Configure Log
  message(CONFIGURE_LOG <text>...)

message([<mode>] "message text" ...)

Record the specified message text in the log.  If more than one message string is given, they are concatenated into a single message with no separator between the strings.

The optional <mode> keyword determines the type of message, which influences the way the message is handled:

FATAL_ERROR

CMake Error, stop processing and generation.

The cmake(1) executable will return a non-zero exit code.

SEND_ERROR

CMake Error, continue processing, but skip generation.

WARNING

CMake Warning, continue processing.

AUTHOR_WARNING

CMake Warning (dev), continue processing.

DEPRECATION

CMake Deprecation Error or Warning if variable CMAKE_ERROR_DEPRECATED or CMAKE_WARN_DEPRECATED is enabled, respectively, else no message.

(none) or NOTICE

Important message printed to stderr to attract user's attention.

STATUS

The main interesting messages that project users might be interested in. Ideally these should be concise, no more than a single line, but still informative.

VERBOSE

Detailed informational messages intended for project users.  These messages should provide additional details that won't be of interest in most cases, but which may be useful to those building the project when they want deeper insight into what's happening.

DEBUG

Detailed informational messages intended for developers working on the project itself as opposed to users who just want to build it.  These messages will not typically be of interest to other users building the project and will often be closely related to internal implementation details.

TRACE

Fine-grained messages with very low-level implementation details.  Messages using this log level would normally only be temporary and would expect to be removed before releasing the project, packaging up the files, etc.

Added in version 3.15: Added the NOTICE, VERBOSE, DEBUG, and TRACE levels.

The CMake command-line tool displays STATUS to TRACE messages on stdout with the message preceded by two hyphens and a space.  All other message types are sent to stderr and are not prefixed with hyphens.  The CMake GUI displays all messages in its log area. The curses interface shows STATUS to TRACE messages one at a time on a status line and other messages in an interactive pop-up box.  The --log-level command-line option to each of these tools can be used to control which messages will be shown.

Added in version 3.17: To make a log level persist between CMake runs, the CMAKE_MESSAGE_LOG_LEVEL variable can be set instead. Note that the command line option takes precedence over the cache variable.

Added in version 3.16: Messages of log levels NOTICE and below will have each line preceded by the content of the CMAKE_MESSAGE_INDENT variable (converted to a single string by concatenating its list items).  For STATUS to TRACE messages, this indenting content will be inserted after the hyphens.

Added in version 3.17: Messages of log levels NOTICE and below can also have each line preceded with context of the form [some.context.example].  The content between the square brackets is obtained by converting the CMAKE_MESSAGE_CONTEXT list variable to a dot-separated string.  The message context will always appear before any indenting content but after any automatically added leading hyphens. By default, message context is not shown, it has to be explicitly enabled by giving the cmake --log-context command-line option or by setting the CMAKE_MESSAGE_CONTEXT_SHOW variable to true.  See the CMAKE_MESSAGE_CONTEXT documentation for usage examples.

CMake Warning and Error message text displays using a simple markup language.  Non-indented text is formatted in line-wrapped paragraphs delimited by newlines.  Indented text is considered pre-formatted.

Added in version 3.17.

A common pattern in CMake output is a message indicating the start of some sort of check, followed by another message reporting the result of that check. For example:

message(STATUS "Looking for someheader.h")
#... do the checks, set checkSuccess with the result
if(checkSuccess)
  message(STATUS "Looking for someheader.h - found")
else()
  message(STATUS "Looking for someheader.h - not found")
endif()

This can be more robustly and conveniently expressed using the CHECK_... keyword form of the message() command:

message(<checkState> "message" ...)

where <checkState> must be one of the following:

CHECK_START

Record a concise message about the check about to be performed.

CHECK_PASS

Record a successful result for a check.

CHECK_FAIL

Record an unsuccessful result for a check.

When recording a check result, the command repeats the message from the most recently started check for which no result has yet been reported, then some separator characters and then the message text provided after the CHECK_PASS or CHECK_FAIL keyword.  Check messages are always reported at STATUS log level.

Checks may be nested and every CHECK_START should have exactly one matching CHECK_PASS or CHECK_FAIL. The CMAKE_MESSAGE_INDENT variable can also be used to add indenting to nested checks if desired.  For example:

message(CHECK_START "Finding my things")
list(APPEND CMAKE_MESSAGE_INDENT "  ")
unset(missingComponents)

message(CHECK_START "Finding partA")
# ... do check, assume we find A
message(CHECK_PASS "found")

message(CHECK_START "Finding partB")
# ... do check, assume we don't find B
list(APPEND missingComponents B)
message(CHECK_FAIL "not found")

list(POP_BACK CMAKE_MESSAGE_INDENT)
if(missingComponents)
  message(CHECK_FAIL "missing components: ${missingComponents}")
else()
  message(CHECK_PASS "all components found")
endif()

Output from the above would appear something like the following:

-- Finding my things
--   Finding partA
--   Finding partA - found
--   Finding partB
--   Finding partB - not found
-- Finding my things - missing components: B

Added in version 3.26.

message(CONFIGURE_LOG <text>...)

Record a configure-log message event with the specified <text>.  By convention, if the text contains more than one line, the first line should be a summary of the event.

This mode is intended to record the details of a system inspection check or other one-time operation guarded by a cache entry, but that is not performed using try_compile() or try_run(), which automatically log their details.  Projects should avoid calling it every time CMake runs.  For example:

if (NOT DEFINED MY_CHECK_RESULT)
  # Print check summary in configure output.
  message(CHECK_START "My Check")

  # ... perform system inspection, e.g., with execute_process ...

  # Cache the result so we do not run the check again.
  set(MY_CHECK_RESULT "${MY_CHECK_RESULT}" CACHE INTERNAL "My Check")

  # Record the check details in the cmake-configure-log.
  message(CONFIGURE_LOG
    "My Check Result: ${MY_CHECK_RESULT}\n"
    "${details}"
  )

  # Print check result in configure output.
  if(MY_CHECK_RESULT)
    message(CHECK_PASS "passed")
  else()
    message(CHECK_FAIL "failed")
  endif()
endif()

If no project is currently being configured, such as in cmake -P script mode, this command does nothing.

• cmake_language(GET_MESSAGE_LOG_LEVEL)

Provide a boolean option that the user can optionally select.

option(<variable> "<help_text>" [value])

If no initial <value> is provided, boolean OFF is the default value. If <variable> is already set as a normal or cache variable, then the command does nothing (see policy CMP0077).

For options that depend on the values of other options, see the module help for CMakeDependentOption.

In CMake project mode, a boolean cache variable is created with the option value. In CMake script mode, a boolean variable is set with the option value.

Return from a file, directory or function.

return([PROPAGATE <var-name>...])

When this command is encountered in an included file (via include() or find_package()), it causes processing of the current file to stop and control is returned to the including file.  If it is encountered in a file which is not included by another file, e.g. a CMakeLists.txt, deferred calls scheduled by cmake_language(DEFER) are invoked and control is returned to the parent directory if there is one.

If return() is called in a function, control is returned to the caller of that function.  Note that a macro(), unlike a function(), is expanded in place and therefore cannot handle return().

Policy CMP0140 controls the behavior regarding the arguments of the command.  All arguments are ignored unless that policy is set to NEW.

PROPAGATE

Added in version 3.25.

This option sets or unsets the specified variables in the parent directory or function caller scope. This is equivalent to set(PARENT_SCOPE) or unset(PARENT_SCOPE) commands, except for the way it interacts with the block() command, as described below.

The PROPAGATE option can be very useful in conjunction with the block() command.  A return will propagate the specified variables through any enclosing block scopes created by the block() commands.  Inside a function, this ensures the variables are propagated to the function's caller, regardless of any blocks within the function.  If not inside a function, it ensures the variables are propagated to the parent file or directory scope. For example:

CMakeLists.txt

cmake_version_required(VERSION 3.25)
project(example)

set(var1 "top-value")

block(SCOPE_FOR VARIABLES)
  add_subdirectory(subDir)
  # var1 has the value "block-nested"
endblock()

# var1 has the value "top-value"

subDir/CMakeLists.txt

function(multi_scopes result_var1 result_var2)
  block(SCOPE_FOR VARIABLES)
    # This would only propagate out of the immediate block, not to
    # the caller of the function.
    #set(${result_var1} "new-value" PARENT_SCOPE)
    #unset(${result_var2} PARENT_SCOPE)

    # This propagates the variables through the enclosing block and
    # out to the caller of the function.
    set(${result_var1} "new-value")
    unset(${result_var2})
    return(PROPAGATE ${result_var1} ${result_var2})
  endblock()
endfunction()

set(var1 "some-value")
set(var2 "another-value")

multi_scopes(var1 var2)
# Now var1 will hold "new-value" and var2 will be unset

block(SCOPE_FOR VARIABLES)
  # This return() will set var1 in the directory scope that included us
  # via add_subdirectory(). The surrounding block() here does not limit
  # propagation to the current file, but the block() in the parent
  # directory scope does prevent propagation going any further.
  set(var1 "block-nested")
  return(PROPAGATE var1)
endblock()

• block()
• function()

Parse command-line arguments into a semicolon-separated list.

separate_arguments(<variable> <mode> [PROGRAM [SEPARATE_ARGS]] <args>)

Parses a space-separated string <args> into a list of items, and stores this list in semicolon-separated standard form in <variable>.

This function is intended for parsing command-line arguments. The entire command line must be passed as one string in the argument <args>.

The exact parsing rules depend on the operating system. They are specified by the <mode> argument which must be one of the following keywords:

UNIX_COMMAND

Arguments are separated by unquoted whitespace. Both single-quote and double-quote pairs are respected. A backslash escapes the next literal character (\" is "); there are no special escapes (\n is just n).

WINDOWS_COMMAND

A Windows command-line is parsed using the same syntax the runtime library uses to construct argv at startup.  It separates arguments by whitespace that is not double-quoted. Backslashes are literal unless they precede double-quotes.  See the MSDN article Parsing C Command-Line Arguments for details.

NATIVE_COMMAND

Added in version 3.9.

Proceeds as in WINDOWS_COMMAND mode if the host system is Windows. Otherwise proceeds as in UNIX_COMMAND mode.

PROGRAM

Added in version 3.19.

The first item in <args> is assumed to be an executable and will be searched in the system search path or left as a full path. If not found, <variable> will be empty. Otherwise, <variable> is a list of 2 elements:

0.

Absolute path of the program

1.

Any command-line arguments present in <args> as a string

For example:

separate_arguments (out UNIX_COMMAND PROGRAM "cc -c main.c")

• First element of the list: /path/to/cc
• Second element of the list: " -c main.c"

SEPARATE_ARGS

When this sub-option of PROGRAM option is specified, command-line arguments will be split as well and stored in <variable>.

For example:

separate_arguments (out UNIX_COMMAND PROGRAM SEPARATE_ARGS "cc -c main.c")

The contents of out will be: /path/to/cc;-c;main.c

separate_arguments(<var>)

Convert the value of <var> to a semi-colon separated list.  All spaces are replaced with ';'.  This helps with generating command lines.

Set a normal, cache, or environment variable to a given value. See the cmake-language(7) variables documentation for the scopes and interaction of normal variables and cache entries.

Signatures of this command that specify a <value>... placeholder expect zero or more arguments.  Multiple arguments will be joined as a semicolon-separated list to form the actual variable value to be set.

set(<variable> <value>... [PARENT_SCOPE])

Set or unset <variable> in the current function or directory scope:

• If at least one <value>... is given, set the variable to that value.
• If no value is given, unset the variable.  This is equivalent to unset(<variable>).

If the PARENT_SCOPE option is given the variable will be set in the scope above the current scope.  Each new directory or function() command creates a new scope.  A scope can also be created with the block() command. set(PARENT_SCOPE) will set the value of a variable into the parent directory, calling function, or encompassing scope (whichever is applicable to the case at hand). The previous state of the variable's value stays the same in the current scope (e.g., if it was undefined before, it is still undefined and if it had a value, it is still that value).

The block(PROPAGATE) and return(PROPAGATE) commands can be used as an alternate method to the set(PARENT_SCOPE) and unset(PARENT_SCOPE) commands to update the parent scope.

NOTE:

When evaluating Variable References of the form ${VAR}, CMake first searches for a normal variable with that name.  If no such normal variable exists, CMake will then search for a cache entry with that name. Because of this, unsetting a normal variable can expose a cache variable that was previously hidden.  To force a variable reference of the form ${VAR} to return an empty string, use set(<variable> ""), which clears the normal variable but leaves it defined.

set(<variable> <value>... CACHE <type> <docstring> [FORCE])

Sets the given cache <variable> (cache entry).  Since cache entries are meant to provide user-settable values this does not overwrite existing cache entries by default.  Use the FORCE option to overwrite existing entries.

The <type> must be specified as one of:

BOOL

Boolean ON/OFF value. cmake-gui(1) offers a checkbox.

FILEPATH

Path to a file on disk. cmake-gui(1) offers a file dialog.

PATH

Path to a directory on disk. cmake-gui(1) offers a file dialog.

STRING

A line of text. cmake-gui(1) offers a text field or a drop-down selection if the STRINGS cache entry property is set.

INTERNAL

A line of text. cmake-gui(1) does not show internal entries. They may be used to store variables persistently across runs. Use of this type implies FORCE.

The <docstring> must be specified as a line of text providing a quick summary of the option for presentation to cmake-gui(1) users.

If the cache entry does not exist prior to the call or the FORCE option is given then the cache entry will be set to the given value.

NOTE:

The content of the cache variable will not be directly accessible if a normal variable of the same name already exists (see rules of variable evaluation). If policy CMP0126 is set to OLD, any normal variable binding in the current scope will be removed.

It is possible for the cache entry to exist prior to the call but have no type set if it was created on the cmake(1) command line by a user through the -D<var>=<value> option without specifying a type.  In this case the set command will add the type.  Furthermore, if the <type> is PATH or FILEPATH and the <value> provided on the command line is a relative path, then the set command will treat the path as relative to the current working directory and convert it to an absolute path.

set(ENV{<variable>} [<value>])

Sets an Environment Variable to the given value. Subsequent calls of $ENV{<variable>} will return this new value.

This command affects only the current CMake process, not the process from which CMake was called, nor the system environment at large, nor the environment of subsequent build or test processes.

If no argument is given after ENV{<variable>} or if <value> is an empty string, then this command will clear any existing value of the environment variable.

Arguments after <value> are ignored. If extra arguments are found, then an author warning is issued.

• unset()

Set properties of the current directory and subdirectories.

set_directory_properties(PROPERTIES <prop1> <value1> [<prop2> <value2>] ...)

Sets properties of the current directory and its subdirectories in key-value pairs.

See also the set_property(DIRECTORY) command.

See Properties on Directories for the list of properties known to CMake and their individual documentation for the behavior of each property.

• define_property()
• get_directory_property()
• the more general set_property() command

Set a named property in a given scope.

set_property(<GLOBAL                      |
              DIRECTORY [<dir>]           |
              TARGET    [<target1> ...]   |
              SOURCE    [<src1> ...]
                        [DIRECTORY <dirs> ...]
                        [TARGET_DIRECTORY <targets> ...] |
              INSTALL   [<file1> ...]     |
              TEST      [<test1> ...]
                        [DIRECTORY <dir>] |
              CACHE     [<entry1> ...]    >
             [APPEND] [APPEND_STRING]
             PROPERTY <name> [<value1> ...])

Sets one property on zero or more objects of a scope.

The first argument determines the scope in which the property is set. It must be one of the following:

GLOBAL

Scope is unique and does not accept a name.

DIRECTORY

Scope defaults to the current directory but other directories (already processed by CMake) may be named by full or relative path. Relative paths are treated as relative to the current source directory. See also the set_directory_properties() command.

Added in version 3.19: <dir> may reference a binary directory.

TARGET

Scope may name zero or more existing targets. See also the set_target_properties() command.

Alias Targets do not support setting target properties.

SOURCE

Scope may name zero or more source files.  By default, source file properties are only visible to targets added in the same directory (CMakeLists.txt).

Added in version 3.18: Visibility can be set in other directory scopes using one or both of the following sub-options:

DIRECTORY <dirs>...

The source file property will be set in each of the <dirs> directories' scopes.  CMake must already know about each of these directories, either by having added them through a call to add_subdirectory() or it being the top level source directory. Relative paths are treated as relative to the current source directory.

Added in version 3.19: <dirs> may reference a binary directory.

TARGET_DIRECTORY <targets>...

The source file property will be set in each of the directory scopes where any of the specified <targets> were created (the <targets> must therefore already exist).

See also the set_source_files_properties() command.

INSTALL

Added in version 3.1.

Scope may name zero or more installed file paths. These are made available to CPack to influence deployment.

Both the property key and value may use generator expressions. Specific properties may apply to installed files and/or directories.

Path components have to be separated by forward slashes, must be normalized and are case sensitive.

To reference the installation prefix itself with a relative path use ..

Currently installed file properties are only defined for the WIX generator where the given paths are relative to the installation prefix.

TEST

Scope is limited to the directory the command is called in. It may name zero or more existing tests. See also command set_tests_properties().

Test property values may be specified using generator expressions for tests created by the add_test(NAME) signature.

Added in version 3.28: Visibility can be set in other directory scopes using the following sub-option:

DIRECTORY <dir>

The test property will be set in the <dir> directory's scope. CMake must already know about this directory, either by having added it through a call to add_subdirectory() or it being the top level source directory. Relative paths are treated as relative to the current source directory. <dir> may reference a binary directory.

CACHE

Scope must name zero or more existing cache entries.

The required PROPERTY option is immediately followed by the name of the property to set.  Remaining arguments are used to compose the property value in the form of a semicolon-separated list.

If the APPEND option is given the list is appended to any existing property value (except that empty values are ignored and not appended). If the APPEND_STRING option is given the string is appended to any existing property value as string, i.e. it results in a longer string and not a list of strings.  When using APPEND or APPEND_STRING with a property defined to support INHERITED behavior (see define_property()), no inheriting occurs when finding the initial value to append to.  If the property is not already directly set in the nominated scope, the command will behave as though APPEND or APPEND_STRING had not been given.

NOTE:

• define_property()
• get_property()
• The cmake-properties(7) manual for a list of properties in each scope.

Set the given variable to the name of the computer.

site_name(variable)

On UNIX-like platforms, if the variable HOSTNAME is set, its value will be executed as a command expected to print out the host name, much like the hostname command-line tool.

String operations.

Search and Replace
  string(FIND <string> <substring> <out-var> [...])
  string(REPLACE <match-string> <replace-string> <out-var> <input>...)
  string(REGEX MATCH <match-regex> <out-var> <input>...)
  string(REGEX MATCHALL <match-regex> <out-var> <input>...)
  string(REGEX REPLACE <match-regex> <replace-expr> <out-var> <input>...)

Manipulation
  string(APPEND <string-var> [<input>...])
  string(PREPEND <string-var> [<input>...])
  string(CONCAT <out-var> [<input>...])
  string(JOIN <glue> <out-var> [<input>...])
  string(TOLOWER <string> <out-var>)
  string(TOUPPER <string> <out-var>)
  string(LENGTH <string> <out-var>)
  string(SUBSTRING <string> <begin> <length> <out-var>)
  string(STRIP <string> <out-var>)
  string(GENEX_STRIP <string> <out-var>)
  string(REPEAT <string> <count> <out-var>)

Comparison
  string(COMPARE <op> <string1> <string2> <out-var>)

Hashing
  string(<HASH> <out-var> <input>)

Generation
  string(ASCII <number>... <out-var>)
  string(HEX <string> <out-var>)
  string(CONFIGURE <string> <out-var> [...])
  string(MAKE_C_IDENTIFIER <string> <out-var>)
  string(RANDOM [<option>...] <out-var>)
  string(TIMESTAMP <out-var> [<format string>] [UTC])
  string(UUID <out-var> ...)

JSON
  string(JSON <out-var> [ERROR_VARIABLE <error-var>]
         {GET | TYPE | LENGTH | REMOVE}
         <json-string> <member|index> [<member|index> ...])
  string(JSON <out-var> [ERROR_VARIABLE <error-var>]
         MEMBER <json-string>
         [<member|index> ...] <index>)
  string(JSON <out-var> [ERROR_VARIABLE <error-var>]
         SET <json-string>
         <member|index> [<member|index> ...] <value>)
  string(JSON <out-var> [ERROR_VARIABLE <error-var>]
         EQUAL <json-string1> <json-string2>)

string(FIND <string> <substring> <output_variable> [REVERSE])

Return the position where the given <substring> was found in the supplied <string>.  If the REVERSE flag was used, the command will search for the position of the last occurrence of the specified <substring>.  If the <substring> is not found, a position of -1 is returned.

The string(FIND) subcommand treats all strings as ASCII-only characters. The index stored in <output_variable> will also be counted in bytes, so strings containing multi-byte characters may lead to unexpected results.

string(REPLACE <match_string> <replace_string> <output_variable> <input> [<input>...])

Replace all occurrences of <match_string> in the <input> with <replace_string> and store the result in the <output_variable>.

string(REGEX MATCH <regular_expression> <output_variable> <input> [<input>...])

Match the <regular_expression> once and store the match in the <output_variable>. All <input> arguments are concatenated before matching. Regular expressions are specified in the subsection just below.

string(REGEX MATCHALL <regular_expression> <output_variable> <input> [<input>...])

Match the <regular_expression> as many times as possible and store the matches in the <output_variable> as a list. All <input> arguments are concatenated before matching.

string(REGEX REPLACE <regular_expression> <replacement_expression> <output_variable> <input> [<input>...])

Match the <regular_expression> as many times as possible and substitute the <replacement_expression> for the match in the output. All <input> arguments are concatenated before matching.

The <replacement_expression> may refer to parenthesis-delimited subexpressions of the match using \1, \2, ..., \9.  Note that two backslashes (\\1) are required in CMake code to get a backslash through argument parsing.

The following characters have special meaning in regular expressions:

^

Matches at beginning of input

$

Matches at end of input

.

Matches any single character

\<char>

Matches the single character specified by <char>.  Use this to match special regex characters, e.g. \. for a literal . or \\ for a literal backslash \.  Escaping a non-special character is unnecessary but allowed, e.g. \a matches a.

[ ]

Matches any character(s) inside the brackets

[^ ]

Matches any character(s) not inside the brackets

-

Inside brackets, specifies an inclusive range between characters on either side e.g. [a-f] is [abcdef] To match a literal - using brackets, make it the first or the last character e.g. [+*/-] matches basic mathematical operators.

*

Matches preceding pattern zero or more times

+

Matches preceding pattern one or more times

?

Matches preceding pattern zero or once only

|

Matches a pattern on either side of the |

()

Saves a matched subexpression, which can be referenced in the REGEX REPLACE operation.

Added in version 3.9: All regular expression-related commands, including e.g. if(MATCHES), save subgroup matches in the variables CMAKE_MATCH_<n> for <n> 0..9.

*, + and ? have higher precedence than concatenation.  | has lower precedence than concatenation.  This means that the regular expression ^ab+d$ matches abbd but not ababd, and the regular expression ^(ab|cd)$ matches ab but not abd.

CMake language Escape Sequences such as \t, \r, \n, and \\ may be used to construct literal tabs, carriage returns, newlines, and backslashes (respectively) to pass in a regex.  For example:

• The quoted argument "[ \t\r\n]" specifies a regex that matches any single whitespace character.
• The quoted argument "[/\\]" specifies a regex that matches a single forward slash / or backslash \.
• The quoted argument "[A-Za-z0-9_]" specifies a regex that matches any single "word" character in the C locale.
• The quoted argument "\\(\\a\\+b\\)" specifies a regex that matches the exact string (a+b).  Each \\ is parsed in a quoted argument as just \, so the regex itself is actually \(\a\+\b\).  This can alternatively be specified in a Bracket Argument without having to escape the backslashes, e.g. [[\(\a\+\b\)]].

string(APPEND <string_variable> [<input>...])

Added in version 3.4.

Append all the <input> arguments to the string.

string(PREPEND <string_variable> [<input>...])

Added in version 3.10.

Prepend all the <input> arguments to the string.

string(CONCAT <output_variable> [<input>...])

Concatenate all the <input> arguments together and store the result in the named <output_variable>.

string(JOIN <glue> <output_variable> [<input>...])

Added in version 3.12.

Join all the <input> arguments together using the <glue> string and store the result in the named <output_variable>.

To join a list's elements, prefer to use the JOIN operator from the list() command.  This allows for the elements to have special characters like ; in them.

string(TOLOWER <string> <output_variable>)

Convert <string> to lower characters.

string(TOUPPER <string> <output_variable>)

Convert <string> to upper characters.

string(LENGTH <string> <output_variable>)

Store in an <output_variable> a given string's length in bytes. Note that this means if <string> contains multi-byte characters, the result stored in <output_variable> will not be the number of characters.

string(SUBSTRING <string> <begin> <length> <output_variable>)

Store in an <output_variable> a substring of a given <string>.  If <length> is -1 the remainder of the string starting at <begin> will be returned.

Changed in version 3.2: If <string> is shorter than <length> then the end of the string is used instead. Previous versions of CMake reported an error in this case.

Both <begin> and <length> are counted in bytes, so care must be exercised if <string> could contain multi-byte characters.

string(STRIP <string> <output_variable>)

Store in an <output_variable> a substring of a given <string> with leading and trailing spaces removed.

string(GENEX_STRIP <string> <output_variable>)

Added in version 3.1.

Strip any generator expressions from the input <string> and store the result in the <output_variable>.

string(REPEAT <string> <count> <output_variable>)

Added in version 3.15.

Produce the output string as the input <string> repeated <count> times.

string(COMPARE LESS <string1> <string2> <output_variable>)

string(COMPARE GREATER <string1> <string2> <output_variable>)

string(COMPARE EQUAL <string1> <string2> <output_variable>)

string(COMPARE NOTEQUAL <string1> <string2> <output_variable>)

string(COMPARE LESS_EQUAL <string1> <string2> <output_variable>)

string(COMPARE GREATER_EQUAL <string1> <string2> <output_variable>)

Compare the strings and store true or false in the <output_variable>.

Added in version 3.7: Added the LESS_EQUAL and GREATER_EQUAL options.

string(<HASH> <output_variable> <input>)

Compute a cryptographic hash of the <input> string. The supported <HASH> algorithm names are:

MD5

Message-Digest Algorithm 5, RFC 1321.

SHA1

US Secure Hash Algorithm 1, RFC 3174.

SHA224

US Secure Hash Algorithms, RFC 4634.

SHA256

US Secure Hash Algorithms, RFC 4634.

SHA384

US Secure Hash Algorithms, RFC 4634.

SHA512

US Secure Hash Algorithms, RFC 4634.

SHA3_224

Keccak SHA-3.

SHA3_256

Keccak SHA-3.

SHA3_384

Keccak SHA-3.

SHA3_512

Keccak SHA-3.

Added in version 3.8: Added the SHA3_* hash algorithms.

string(ASCII <number> [<number> ...] <output_variable>)

Convert all numbers into corresponding ASCII characters.

string(HEX <string> <output_variable>)

Added in version 3.18.

Convert each byte in the input <string> to its hexadecimal representation and store the concatenated hex digits in the <output_variable>. Letters in the output (a through f) are in lowercase.

string(CONFIGURE <string> <output_variable> [@ONLY] [ESCAPE_QUOTES])

Transform a <string> like configure_file() transforms a file.

string(MAKE_C_IDENTIFIER <string> <output_variable>)

Convert each non-alphanumeric character in the input <string> to an underscore and store the result in the <output_variable>.  If the first character of the <string> is a digit, an underscore will also be prepended to the result.

string(RANDOM [LENGTH <length>] [ALPHABET <alphabet>] [RANDOM_SEED <seed>] <output_variable>)

Return a random string of given <length> consisting of characters from the given <alphabet>.  Default length is 5 characters and default alphabet is all numbers and upper and lower case letters. If an integer RANDOM_SEED is given, its value will be used to seed the random number generator.

string(TIMESTAMP <output_variable> [<format_string>] [UTC])

Write a string representation of the current date and/or time to the <output_variable>.

If the command is unable to obtain a timestamp, the <output_variable> will be set to the empty string "".

The optional UTC flag requests the current date/time representation to be in Coordinated Universal Time (UTC) rather than local time.

The optional <format_string> may contain the following format specifiers:

%%

Added in version 3.8.

A literal percent sign (%).

%d

The day of the current month (01-31).

%H

The hour on a 24-hour clock (00-23).

%I

The hour on a 12-hour clock (01-12).

%j

The day of the current year (001-366).

%m

The month of the current year (01-12).

%b

Added in version 3.7.

Abbreviated month name (e.g. Oct).

%B

Added in version 3.10.

Full month name (e.g. October).

%M

The minute of the current hour (00-59).

%s

Added in version 3.6.

Seconds since midnight (UTC) 1-Jan-1970 (UNIX time).

%S

The second of the current minute.  60 represents a leap second. (00-60)

%f

Added in version 3.23.

The microsecond of the current second (000000-999999).

%U

The week number of the current year (00-53).

%V

Added in version 3.22.

The ISO 8601 week number of the current year (01-53).

%w

The day of the current week. 0 is Sunday. (0-6)

%a

Added in version 3.7.

Abbreviated weekday name (e.g. Fri).

%A

Added in version 3.10.

Full weekday name (e.g. Friday).

%y

The last two digits of the current year (00-99).

%Y

The current year.

%z

Added in version 3.26.

The offset of the time zone from UTC, in hours and minutes, with format +hhmm or -hhmm.

%Z

Added in version 3.26.

The time zone name.

Unknown format specifiers will be ignored and copied to the output as-is.

If no explicit <format_string> is given, it will default to:

%Y-%m-%dT%H:%M:%S    for local time.
%Y-%m-%dT%H:%M:%SZ   for UTC.

Added in version 3.8: If the SOURCE_DATE_EPOCH environment variable is set, its value will be used instead of the current time. See https://reproducible-builds.org/specs/source-date-epoch/ for details.

string(UUID <output_variable> NAMESPACE <namespace> NAME <name> TYPE <MD5|SHA1> [UPPER])

Added in version 3.1.

Create a universally unique identifier (aka GUID) as per RFC4122 based on the hash of the combined values of <namespace> (which itself has to be a valid UUID) and <name>. The hash algorithm can be either MD5 (Version 3 UUID) or SHA1 (Version 5 UUID). A UUID has the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx where each x represents a lower case hexadecimal character. Where required, an uppercase representation can be requested with the optional UPPER flag.

Added in version 3.19.

Functionality for querying a JSON string.

NOTE:

In each of the following JSON-related subcommands, if the optional ERROR_VARIABLE argument is given, errors will be reported in <error-variable> and the <out-var> will be set to <member|index>-[<member|index>...]-NOTFOUND with the path elements up to the point where the error occurred, or just NOTFOUND if there is no relevant path.  If an error occurs but the ERROR_VARIABLE option is not present, a fatal error message is generated.  If no error occurs, the <error-variable> will be set to NOTFOUND.

string(JSON <out-var> [ERROR_VARIABLE <error-variable>] GET <json-string> <member|index> [<member|index> ...])

Get an element from <json-string> at the location given by the list of <member|index> arguments. Array and object elements will be returned as a JSON string. Boolean elements will be returned as ON or OFF. Null elements will be returned as an empty string. Number and string types will be returned as strings.

string(JSON <out-var> [ERROR_VARIABLE <error-variable>] TYPE <json-string> <member|index> [<member|index> ...])

Get the type of an element in <json-string> at the location given by the list of <member|index> arguments. The <out-var> will be set to one of NULL, NUMBER, STRING, BOOLEAN, ARRAY, or OBJECT.

string(JSON <out-var> [ERROR_VARIABLE <error-var>] MEMBER <json-string> [<member|index> ...] <index>)

Get the name of the <index>-th member in <json-string> at the location given by the list of <member|index> arguments. Requires an element of object type.

string(JSON <out-var> [ERROR_VARIABLE <error-variable>] LENGTH <json-string> [<member|index> ...])

Get the length of an element in <json-string> at the location given by the list of <member|index> arguments. Requires an element of array or object type.

string(JSON <out-var> [ERROR_VARIABLE <error-variable>] REMOVE <json-string> <member|index> [<member|index> ...])

Remove an element from <json-string> at the location given by the list of <member|index> arguments. The JSON string without the removed element will be stored in <out-var>.

string(JSON <out-var> [ERROR_VARIABLE <error-variable>] SET <json-string> <member|index> [<member|index> ...] <value>)

Set an element in <json-string> at the location given by the list of <member|index> arguments to <value>. The contents of <value> should be valid JSON. If <json-string> is an array, <value> can be appended to the end of the array by using a number greater or equal to the array length as the <member|index> argument.

string(JSON <out-var> [ERROR_VARIABLE <error-var>] EQUAL <json-string1> <json-string2>)

Compare the two JSON objects given by <json-string1> and <json-string2> for equality.  The contents of <json-string1> and <json-string2> should be valid JSON.  The <out-var> will be set to a true value if the JSON objects are considered equal, or a false value otherwise.

Unset a variable, cache variable, or environment variable.

unset(<variable> [CACHE | PARENT_SCOPE])

Removes a normal variable from the current scope, causing it to become undefined.  If CACHE is present, then a cache variable is removed instead of a normal variable.

If PARENT_SCOPE is present then the variable is removed from the scope above the current scope.  See the same option in the set() command for further details.

NOTE:

unset(ENV{<variable>})

Removes <variable> from the currently available Environment Variables. Subsequent calls of $ENV{<variable>} will return the empty string.

This command affects only the current CMake process, not the process from which CMake was called, nor the system environment at large, nor the environment of subsequent build or test processes.

• set()

Watch the CMake variable for change.

variable_watch(<variable> [<command>])

If the specified <variable> changes and no <command> is given, a message will be printed to inform about the change.

If <command> is given, this command will be executed instead. The command will receive the following arguments: COMMAND(<variable> <access> <value> <current_list_file> <stack>)

<variable>

Name of the variable being accessed.

<access>

One of READ_ACCESS, UNKNOWN_READ_ACCESS, MODIFIED_ACCESS, UNKNOWN_MODIFIED_ACCESS, or REMOVED_ACCESS.  The UNKNOWN_ values are only used when the variable has never been set.  Once set, they are never used again during the same CMake run, even if the variable is later unset.

<value>

The value of the variable.  On a modification, this is the new (modified) value of the variable.  On removal, the value is empty.

<current_list_file>

Full path to the file doing the access.

<stack>

List of absolute paths of all files currently on the stack of file inclusion, with the bottom-most file first and the currently processed file (that is, current_list_file) last.

Note that for some accesses such as list(APPEND), the watcher is executed twice, first with a read access and then with a write one. Also note that an if(DEFINED) query on the variable does not register as an access and the watcher is not executed.

Only non-cache variables can be watched using this command.  Access to cache variables is never watched.  However, the existence of a cache variable var causes accesses to the non-cache variable var to not use the UNKNOWN_ prefix, even if a non-cache variable var has never existed.

Evaluate a group of commands while a condition is true

while(<condition>)
  <commands>
endwhile()

All commands between while and the matching endwhile() are recorded without being invoked.  Once the endwhile() is evaluated, the recorded list of commands is invoked as long as the <condition> is true.

The <condition> has the same syntax and is evaluated using the same logic as described at length for the if() command.

The commands break() and continue() provide means to escape from the normal control flow.

Per legacy, the endwhile() command admits an optional <condition> argument. If used, it must be a verbatim repeat of the argument of the opening while command.

• break()
• continue()
• foreach()
• endwhile()

Added in version 3.12.

Add preprocessor definitions to the compilation of source files.

add_compile_definitions(<definition> ...)

Adds preprocessor definitions to the compiler command line.

The preprocessor definitions are added to the COMPILE_DEFINITIONS directory property for the current CMakeLists file. They are also added to the COMPILE_DEFINITIONS target property for each target in the current CMakeLists file.

Definitions are specified using the syntax VAR or VAR=value. Function-style definitions are not supported. CMake will automatically escape the value correctly for the native build system (note that CMake language syntax may require escapes to specify some values).

Added in version 3.26: Any leading -D on an item will be removed.

Arguments to add_compile_definitions may use generator expressions with the syntax $<...>. See the cmake-generator-expressions(7) manual for available expressions.  See the cmake-buildsystem(7) manual for more on defining buildsystem properties.

• The command target_compile_definitions() adds target-specific definitions.

Add options to the compilation of source files.

add_compile_options(<option> ...)

Adds options to the COMPILE_OPTIONS directory property. These options are used when compiling targets from the current directory and below.

NOTE:

Arguments to add_compile_options may use generator expressions with the syntax $<...>. See the cmake-generator-expressions(7) manual for available expressions.  See the cmake-buildsystem(7) manual for more on defining buildsystem properties.

The final set of options used for a target is constructed by accumulating options from the current target and the usage requirements of its dependencies.  The set of options is de-duplicated to avoid repetition.

Added in version 3.12: While beneficial for individual options, the de-duplication step can break up option groups.  For example, -option A -option B becomes -option A B.  One may specify a group of options using shell-like quoting along with a SHELL: prefix.  The SHELL: prefix is dropped, and the rest of the option string is parsed using the separate_arguments() UNIX_COMMAND mode. For example, "SHELL:-option A" "SHELL:-option B" becomes -option A -option B.

Since different compilers support different options, a typical use of this command is in a compiler-specific conditional clause:

if (MSVC)
    # warning level 4
    add_compile_options(/W4)
else()
    # additional warnings
    add_compile_options(-Wall -Wextra -Wpedantic)
endif()

To set per-language options, use the $<COMPILE_LANGUAGE> or $<COMPILE_LANGUAGE:languages> generator expressions.

• This command can be used to add any options. However, for adding preprocessor definitions and include directories it is recommended to use the more specific commands add_compile_definitions() and include_directories().
• The command target_compile_options() adds target-specific options.
• This command adds compile options for all languages. Use the COMPILE_LANGUAGE generator expression to specify per-language compile options.
• The source file property COMPILE_OPTIONS adds options to one source file.
• add_link_options() adds options for linking.
• CMAKE_<LANG>_FLAGS and CMAKE_<LANG>_FLAGS_<CONFIG> add language-wide flags passed to all invocations of the compiler. This includes invocations that drive compiling and those that drive linking.

Add a custom build rule to the generated build system.

There are two main signatures for add_custom_command.

The first signature is for adding a custom command to produce an output:

add_custom_command(OUTPUT output1 [output2 ...]
                   COMMAND command1 [ARGS] [args1...]
                   [COMMAND command2 [ARGS] [args2...] ...]
                   [MAIN_DEPENDENCY depend]
                   [DEPENDS [depends...]]
                   [BYPRODUCTS [files...]]
                   [IMPLICIT_DEPENDS <lang1> depend1
                                    [<lang2> depend2] ...]
                   [WORKING_DIRECTORY dir]
                   [COMMENT comment]
                   [DEPFILE depfile]
                   [JOB_POOL job_pool]
                   [JOB_SERVER_AWARE <bool>]
                   [VERBATIM] [APPEND] [USES_TERMINAL]
                   [COMMAND_EXPAND_LISTS]
                   [DEPENDS_EXPLICIT_ONLY])

This defines a command to generate specified OUTPUT file(s). A target created in the same directory (CMakeLists.txt file) that specifies any output of the custom command as a source file is given a rule to generate the file using the command at build time.

Do not list the output in more than one independent target that may build in parallel or the instances of the rule may conflict. Instead, use the add_custom_target() command to drive the command and make the other targets depend on that one.  See the Example: Generating Files for Multiple Targets below.

The options are:

APPEND

Append the COMMAND and DEPENDS option values to the custom command for the first output specified.  There must have already been a previous call to this command with the same output.

If the previous call specified the output via a generator expression, the output specified by the current call must match in at least one configuration after evaluating generator expressions.  In this case, the appended commands and dependencies apply to all configurations.

The COMMENT, MAIN_DEPENDENCY, and WORKING_DIRECTORY options are currently ignored when APPEND is given, but may be used in the future.

BYPRODUCTS

Added in version 3.2.

Specify the files the command is expected to produce but whose modification time may or may not be newer than the dependencies. If a byproduct name is a relative path it will be interpreted relative to the build tree directory corresponding to the current source directory. Each byproduct file will be marked with the GENERATED source file property automatically.

See policy CMP0058 for the motivation behind this feature.

Explicit specification of byproducts is supported by the Ninja generator to tell the ninja build tool how to regenerate byproducts when they are missing.  It is also useful when other build rules (e.g. custom commands) depend on the byproducts.  Ninja requires a build rule for any generated file on which another rule depends even if there are order-only dependencies to ensure the byproducts will be available before their dependents build.

The Makefile Generators will remove BYPRODUCTS and other GENERATED files during make clean.

Added in version 3.20: Arguments to BYPRODUCTS may use a restricted set of generator expressions. Target-dependent expressions are not permitted.

Changed in version 3.28: In targets using File Sets, custom command byproducts are now considered private unless they are listed in a non-private file set. See policy CMP0154.

COMMAND

Specify the command-line(s) to execute at build time. If more than one COMMAND is specified they will be executed in order, but not necessarily composed into a stateful shell or batch script. (To run a full script, use the configure_file() command or the file(GENERATE) command to create it, and then specify a COMMAND to launch it.) The optional ARGS argument is for backward compatibility and will be ignored.

If COMMAND specifies an executable target name (created by the add_executable() command), it will automatically be replaced by the location of the executable created at build time if either of the following is true:

• The target is not being cross-compiled (i.e. the CMAKE_CROSSCOMPILING variable is not set to true).
• Added in version 3.6: The target is being cross-compiled and an emulator is provided (i.e. its CROSSCOMPILING_EMULATOR target property is set). In this case, the contents of CROSSCOMPILING_EMULATOR will be prepended to the command before the location of the target executable.

If neither of the above conditions are met, it is assumed that the command name is a program to be found on the PATH at build time.

Arguments to COMMAND may use generator expressions. Use the TARGET_FILE generator expression to refer to the location of a target later in the command line (i.e. as a command argument rather than as the command to execute).

Whenever one of the following target based generator expressions are used as a command to execute or is mentioned in a command argument, a target-level dependency will be added automatically so that the mentioned target will be built before any target using this custom command (see policy CMP0112).

• TARGET_FILE
• TARGET_LINKER_FILE
• TARGET_SONAME_FILE
• TARGET_PDB_FILE

This target-level dependency does NOT add a file-level dependency that would cause the custom command to re-run whenever the executable is recompiled. List target names with the DEPENDS option to add such file-level dependencies.

COMMENT

Display the given message before the commands are executed at build time.

Added in version 3.26: Arguments to COMMENT may use generator expressions.

DEPENDS

Specify files on which the command depends.  Each argument is converted to a dependency as follows:

1. If the argument is the name of a target (created by the add_custom_target(), add_executable(), or add_library() command) a target-level dependency is created to make sure the target is built before any target using this custom command.  Additionally, if the target is an executable or library, a file-level dependency is created to cause the custom command to re-run whenever the target is recompiled.
2. If the argument is an absolute path, a file-level dependency is created on that path.
3. If the argument is the name of a source file that has been added to a target or on which a source file property has been set, a file-level dependency is created on that source file.
4. If the argument is a relative path and it exists in the current source directory, a file-level dependency is created on that file in the current source directory.
5. Otherwise, a file-level dependency is created on that path relative to the current binary directory.

If any dependency is an OUTPUT of another custom command in the same directory (CMakeLists.txt file), CMake automatically brings the other custom command into the target in which this command is built.

Added in version 3.16: A target-level dependency is added if any dependency is listed as BYPRODUCTS of a target or any of its build events in the same directory to ensure the byproducts will be available.

If DEPENDS is not specified, the command will run whenever the OUTPUT is missing; if the command does not actually create the OUTPUT, the rule will always run.

Added in version 3.1: Arguments to DEPENDS may use generator expressions.

COMMAND_EXPAND_LISTS

Added in version 3.8.

Lists in COMMAND arguments will be expanded, including those created with generator expressions, allowing COMMAND arguments such as ${CC} "-I$<JOIN:$<TARGET_PROPERTY:foo,INCLUDE_DIRECTORIES>,;-I>" foo.cc to be properly expanded.

IMPLICIT_DEPENDS

Request scanning of implicit dependencies of an input file. The language given specifies the programming language whose corresponding dependency scanner should be used. Currently only C and CXX language scanners are supported. The language has to be specified for every file in the IMPLICIT_DEPENDS list.  Dependencies discovered from the scanning are added to those of the custom command at build time. Note that the IMPLICIT_DEPENDS option is currently supported only for Makefile generators and will be ignored by other generators.

NOTE:

This option cannot be specified at the same time as DEPFILE option.

JOB_POOL

Added in version 3.15.

Specify a pool for the Ninja generator. Incompatible with USES_TERMINAL, which implies the console pool. Using a pool that is not defined by JOB_POOLS causes an error by ninja at build time.

JOB_SERVER_AWARE

Added in version 3.28.

Specify that the command is GNU Make job server aware.

For the Unix Makefiles, MSYS Makefiles, and MinGW Makefiles generators this will add the + prefix to the recipe line. See the GNU Make Documentation for more information.

This option is silently ignored by other generators.

MAIN_DEPENDENCY

Specify the primary input source file to the command.  This is treated just like any value given to the DEPENDS option but also suggests to Visual Studio generators where to hang the custom command. Each source file may have at most one command specifying it as its main dependency. A compile command (i.e. for a library or an executable) counts as an implicit main dependency which gets silently overwritten by a custom command specification.

OUTPUT

Specify the output files the command is expected to produce. Each output file will be marked with the GENERATED source file property automatically. If the output of the custom command is not actually created as a file on disk it should be marked with the SYMBOLIC source file property.

If an output file name is a relative path, its absolute path is determined by interpreting it relative to:

1. the build directory corresponding to the current source directory (CMAKE_CURRENT_BINARY_DIR), or
2. the current source directory (CMAKE_CURRENT_SOURCE_DIR).

The path in the build directory is preferred unless the path in the source tree is mentioned as an absolute source file path elsewhere in the current directory.

Added in version 3.20: Arguments to OUTPUT may use a restricted set of generator expressions. Target-dependent expressions are not permitted.

Changed in version 3.28: In targets using File Sets, custom command outputs are now considered private unless they are listed in a non-private file set. See policy CMP0154.

USES_TERMINAL

Added in version 3.2.

The command will be given direct access to the terminal if possible. With the Ninja generator, this places the command in the console pool.

VERBATIM

All arguments to the commands will be escaped properly for the build tool so that the invoked command receives each argument unchanged.  Note that one level of escapes is still used by the CMake language processor before add_custom_command even sees the arguments.  Use of VERBATIM is recommended as it enables correct behavior.  When VERBATIM is not given the behavior is platform specific because there is no protection of tool-specific special characters.

WORKING_DIRECTORY

Execute the command with the given current working directory. If it is a relative path it will be interpreted relative to the build tree directory corresponding to the current source directory.

Added in version 3.13: Arguments to WORKING_DIRECTORY may use generator expressions.

DEPFILE

Added in version 3.7.

Specify a depfile which holds dependencies for the custom command. It is usually emitted by the custom command itself.  This keyword may only be used if the generator supports it, as detailed below.

The expected format, compatible with what is generated by gcc with the option -M, is independent of the generator or platform.

The formal syntax, as specified using BNF notation with the regular extensions, is the following:

depfile       ::=  rule*
rule          ::=  targets (':' (separator dependencies?)?)? eol
targets       ::=  target (separator target)* separator*
target        ::=  pathname
dependencies  ::=  dependency (separator dependency)* separator*
dependency    ::=  pathname
separator     ::=  (space | line_continue)+
line_continue ::=  '\' eol
space         ::=  ' ' | '\t'
pathname      ::=  character+
character     ::=  std_character | dollar | hash | whitespace
std_character ::=  <any character except '$', '#' or ' '>
dollar        ::=  '$$'
hash          ::=  '\#'
whitespace    ::=  '\ '
eol           ::=  '\r'? '\n'

NOTE:

As part of pathname, any slash and backslash is interpreted as a directory separator.

Added in version 3.7: The Ninja generator supports DEPFILE since the keyword was first added.

Added in version 3.17: Added the Ninja Multi-Config generator, which included support for the DEPFILE keyword.

Added in version 3.20: Added support for Makefile Generators.

NOTE:

DEPFILE cannot be specified at the same time as the IMPLICIT_DEPENDS option for Makefile Generators.

Added in version 3.21: Added support for Visual Studio Generators with VS 2012 and above, and for the Xcode generator.  Support for generator expressions was also added.

Using DEPFILE with generators other than those listed above is an error.

If the DEPFILE argument is relative, it should be relative to CMAKE_CURRENT_BINARY_DIR, and any relative paths inside the DEPFILE should also be relative to CMAKE_CURRENT_BINARY_DIR. See policy CMP0116, which is always NEW for Makefile Generators, Visual Studio Generators, and the Xcode generator.

DEPENDS_EXPLICIT_ONLY

Added in version 3.27.

Indicates that the command's DEPENDS argument represents all files required by the command and implicit dependencies are not required.

Without this option, if any target uses the output of the custom command, CMake will consider that target's dependencies as implicit dependencies for the custom command in case this custom command requires files implicitly created by those targets.

This option can be enabled on all custom commands by setting CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY to ON.

Only the Ninja Generators actually use this information to remove unnecessary implicit dependencies.

See also the OPTIMIZE_DEPENDENCIES target property, which may provide another way for reducing the impact of target dependencies in some scenarios.

Custom commands may be used to generate source files. For example, the code:

add_custom_command(
  OUTPUT out.c
  COMMAND someTool -i ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
                   -o out.c
  DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
  VERBATIM)
add_library(myLib out.c)

adds a custom command to run someTool to generate out.c and then compile the generated source as part of a library.  The generation rule will re-run whenever in.txt changes.

Added in version 3.20: One may use generator expressions to specify per-configuration outputs. For example, the code:

add_custom_command(
  OUTPUT "out-$<CONFIG>.c"
  COMMAND someTool -i ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
                   -o "out-$<CONFIG>.c"
                   -c "$<CONFIG>"
  DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/in.txt
  VERBATIM)
add_library(myLib "out-$<CONFIG>.c")

adds a custom command to run someTool to generate out-<config>.c, where <config> is the build configuration, and then compile the generated source as part of a library.

If multiple independent targets need the same custom command output, it must be attached to a single custom target on which they all depend. Consider the following example:

add_custom_command(
  OUTPUT table.csv
  COMMAND makeTable -i ${CMAKE_CURRENT_SOURCE_DIR}/input.dat
                    -o table.csv
  DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/input.dat
  VERBATIM)
add_custom_target(generate_table_csv DEPENDS table.csv)

add_custom_command(
  OUTPUT foo.cxx
  COMMAND genFromTable -i table.csv -case foo -o foo.cxx
  DEPENDS table.csv           # file-level dependency
          generate_table_csv  # target-level dependency
  VERBATIM)
add_library(foo foo.cxx)

add_custom_command(
  OUTPUT bar.cxx
  COMMAND genFromTable -i table.csv -case bar -o bar.cxx
  DEPENDS table.csv           # file-level dependency
          generate_table_csv  # target-level dependency
  VERBATIM)
add_library(bar bar.cxx)

Output foo.cxx is needed only by target foo and output bar.cxx is needed only by target bar, but both targets need table.csv, transitively.  Since foo and bar are independent targets that may build concurrently, we prevent them from racing to generate table.csv by placing its custom command in a separate target, generate_table_csv. The custom commands generating foo.cxx and bar.cxx each specify a target-level dependency on generate_table_csv, so the targets using them, foo and bar, will not build until after target generate_table_csv is built.