strace - Man Page

-e expr

A qualifying expression which modifies which events to trace or how to trace them.  The format of the expression is:

[qualifier=][!]value[,value]...

where qualifier is one of trace (or t), trace-fds (or trace-fd or fd or fds), abbrev (or a), verbose (or v), raw (or x), signal (or signals or s), read (or reads or r), write (or writes or w), fault, inject, status, quiet (or silent or silence or q), secontext, decode-fds (or decode-fd), decode-pids (or decode-pid), or kvm, and value is a qualifier-dependent symbol or number.  The default qualifier is trace. Using an exclamation mark negates the set of values.  For example, -e open means literally -e trace=open which in turn means trace only the open system call.  By contrast, -e trace=!open means to trace every system call except open. In addition, the special values all and none have the obvious meanings.

Note that some shells use the exclamation point for history expansion even inside quoted arguments.  If so, you must escape the exclamation point with a backslash.

-E var=val

--env=var=val

Run command with var=val in its list of environment variables.

-E var

--env=var

Remove var from the inherited list of environment variables before passing it on to the command.

-p pid

--attach=pid

Attach to the process with the process ID pid and begin tracing. The trace may be terminated at any time by a keyboard interrupt signal (CTRL-C). strace will respond by detaching itself from the traced process(es) leaving it (them) to continue running. Multiple -p options can be used to attach to many processes in addition to command (which is optional if at least one -p option is given). Multiple process IDs, separated by either comma (“,”), space (“ ”), tab, or newline character, can be provided as an argument to a single -p option, so, for example, -p "$(pidof PROG)" and -p "$(pgrep PROG)" syntaxes are supported.

-u username

--user=username

Run command with the user ID, group ID, and supplementary groups of username. This option is only useful when running as root and enables the correct execution of setuid and/or setgid binaries. Unless this option is used setuid and setgid programs are executed without effective privileges.

-u UID:GID

--user=UID:GID

Alternative syntax where the program is started with exactly the given user and group IDs, and an empty list of supplementary groups.  In this case, user and group name lookups are not performed.

--argv0=name

Set argv[0] of the command being executed to name. Useful for tracing multi-call executables which interpret argv[0], such as busybox or kmod.

-b syscall

--detach-on=syscall

If specified syscall is reached, detach from traced process. Currently, only execve(2) syscall is supported.  This option is useful if you want to trace multi-threaded process and therefore require -f, but don't want to trace its (potentially very complex) children.

-D

--daemonize

--daemonize=grandchild

Run tracer process as a grandchild, not as the parent of the tracee.  This reduces the visible effect of strace by keeping the tracee a direct child of the calling process.

-DD

--daemonize=pgroup

--daemonize=pgrp

Run tracer process as tracee's grandchild in a separate process group. In addition to reduction of the visible effect of strace, it also avoids killing of strace with kill(2) issued to the whole process group.

-DDD

--daemonize=session

Run tracer process as tracee's grandchild in a separate session ("true daemonisation"). In addition to reduction of the visible effect of strace, it also avoids killing of strace upon session termination.

-f

--follow-forks

Trace child processes as they are created by currently traced processes as a result of the fork(2), vfork(2) and clone(2) system calls.  Note that -p PID -f will attach all threads of process PID if it is multi-threaded, not only thread with thread_id = PID.

--output-separately

If the --output=filename option is in effect, each processes trace is written to filename.pid where pid is the numeric process id of each process.

-ff

--follow-forks --output-separately

Combine the effects of --follow-forks and --output-separately options. This is incompatible with -c, since no per-process counts are kept.

One might want to consider using strace-log-merge(1) to obtain a combined strace log view.

-I interruptible

--interruptible=interruptible

When strace can be interrupted by signals (such as pressing CTRL-C).

1, anywhere

no signals are blocked;

2, waiting

fatal signals are blocked while decoding syscall (default);

3, never

fatal signals are always blocked (default if -o FILE PROG);

4, never_tstp

fatal signals and SIGTSTP (CTRL-Z) are always blocked (useful to make strace -o FILE PROG not stop on CTRL-Z, default if -D).

--syscall-limit=limit

Detach all tracees when limit number of syscalls have been captured. Syscalls filtered out via --trace, --trace-path or --status options are not considered when keeping track of the number of syscalls that are captured.

--kill-on-exit

Apply PTRACE_O_EXITKILL ptrace option to all tracee processes (which sends a SIGKILL signal to the tracee if the tracer exits) and do not detach them on cleanup so they will not be left running after the tracer exit. --kill-on-exit is not compatible with -p/--attach options.

-e trace=syscall_set

-e t=syscall_set

--trace=syscall_set

Trace only the specified set of system calls. syscall_set is defined as [!]value[,value], and value can be one of the following:

syscall

Trace specific syscall, specified by its name (see syscalls(2) for a reference, but also see Notes).

?value

Question mark before the syscall qualification allows suppression of error in case no syscalls matched the qualification provided.

value@64

Limit the syscall specification described by value to 64-bit personality.

value@32

Limit the syscall specification described by value to 32-bit personality.

value@x32

Limit the syscall specification described by value to x32 personality.

all

Trace all system calls.

/regex

Trace only those system calls that match the regex. You can use POSIX Extended Regular Expression syntax (see regex(7)).

%file

file

Trace all system calls which take a file name as an argument.  You can think of this as an abbreviation for -e trace=open,stat,chmod,unlink,... which is useful to seeing what files the process is referencing. Furthermore, using the abbreviation will ensure that you don't accidentally forget to include a call like lstat(2) in the list.  Betchya woulda forgot that one. The syntax without a preceding percent sign ("-e trace=file") is deprecated.

%process

process

Trace system calls associated with process lifecycle (creation, exec, termination). The syntax without a preceding percent sign ("-e trace=process") is deprecated.

%net

%network

network

Trace all the network related system calls. The syntax without a preceding percent sign ("-e trace=network") is deprecated.

%signal

signal

Trace all signal related system calls. The syntax without a preceding percent sign ("-e trace=signal") is deprecated.

%ipc

ipc

Trace all IPC related system calls. The syntax without a preceding percent sign ("-e trace=ipc") is deprecated.

%desc

desc

Trace all file descriptor related system calls. The syntax without a preceding percent sign ("-e trace=desc") is deprecated.

%memory

memory

Trace all memory mapping related system calls. The syntax without a preceding percent sign ("-e trace=memory") is deprecated.

%creds

Trace system calls that read or modify user and group identifiers or capability sets.

%stat

Trace stat syscall variants.

%lstat

Trace lstat syscall variants.

%fstat

Trace fstat, fstatat, and statx syscall variants.

%%stat

Trace syscalls used for requesting file status (stat, lstat, fstat, fstatat, statx, and their variants).

%statfs

Trace statfs, statfs64, statvfs, osf_statfs, and osf_statfs64 system calls. The same effect can be achieved with -e trace=/^(.*_)?statv?fs regular expression.

%fstatfs

Trace fstatfs, fstatfs64, fstatvfs, osf_fstatfs, and osf_fstatfs64 system calls. The same effect can be achieved with -e trace=/fstatv?fs regular expression.

%%statfs

Trace syscalls related to file system statistics (statfs-like, fstatfs-like, and ustat).  The same effect can be achieved with -e trace=/statv?fs|fsstat|ustat regular expression.

%clock

Trace system calls that read or modify system clocks.

%pure

Trace syscalls that always succeed and have no arguments. Currently, this list includes arc_gettls(2), getdtablesize(2), getegid(2), getegid32(2), geteuid(2), geteuid32(2), getgid(2), getgid32(2), getpagesize(2), getpgrp(2), getpid(2), getppid(2), get_thread_area(2) (on architectures other than x86), gettid(2), get_tls(2), getuid(2), getuid32(2), getxgid(2), getxpid(2), getxuid(2), kern_features(2), and metag_get_tls(2) syscalls.

The -c option is useful for determining which system calls might be useful to trace.  For example, trace=open,close,read,write means to only trace those four system calls.  Be careful when making inferences about the user/kernel boundary if only a subset of system calls are being monitored.  The default is trace=all.

-e trace-fd=set

-e trace-fds=set

-e fd=set

-e fds=set

--trace-fds=set

Trace only the syscalls that operate on the specified subset of (non-negative) file descriptors. Note that usage of this option also filters out all the syscalls that do not operate on file descriptors at all. Applies in (inclusive) disjunction with the --trace-path option.

-e signal=set

-e signals=set

-e s=set

--signal=set

Trace only the specified subset of signals.  The default is signal=all. For example, signal=!SIGIO (or signal=!io) causes SIGIO signals not to be traced.

-e status=set

--status=set

Print only system calls with the specified return status.  The default is status=all. When using the status qualifier, because strace waits for system calls to return before deciding whether they should be printed or not, the traditional order of events may not be preserved anymore.  If two system calls are executed by concurrent threads, strace will first print both the entry and exit of the first system call to exit, regardless of their respective entry time.  The entry and exit of the second system call to exit will be printed afterwards.  Here is an example when select(2) is called, but a different thread calls clock_gettime(2) before select(2) finishes:

[pid 28779] 1130322148.939977 clock_gettime(CLOCK_REALTIME, {1130322148, 939977000}) = 0
[pid 28772] 1130322148.438139 select(4, [3], NULL, NULL, NULL) = 1 (in [3])

set can include the following elements:

successful

Trace system calls that returned without an error code. The -z option has the effect of status=successful.

failed

Trace system calls that returned with an error code. The -Z option has the effect of status=failed.

unfinished

Trace system calls that did not return.  This might happen, for example, due to an execve call in a neighbour thread.

unavailable

Trace system calls that returned but strace failed to fetch the error status.

detached

Trace system calls for which strace detached before the return.

-P path

--trace-path=path

Trace only system calls accessing path. Multiple -P options can be used to specify several paths. Applies in (inclusive) disjunction with the --trace-fds option.

-z

--successful-only

Print only syscalls that returned without an error code.

-Z

--failed-only

Print only syscalls that returned with an error code.

-a column

--columns=column

Align return values in a specific column (default column 40).

-e abbrev=syscall_set

-e a=syscall_set

--abbrev=syscall_set

Abbreviate the output from printing each member of large structures. The syntax of the syscall_set specification is the same as in the -e trace option. The default is abbrev=all. The -v option has the effect of abbrev=none.

-e verbose=syscall_set

-e v=syscall_set

--verbose=syscall_set

Dereference structures for the specified set of system calls. The syntax of the syscall_set specification is the same as in the -e trace option. The default is verbose=all.

-e raw=syscall_set

-e x=syscall_set

--raw=syscall_set

Print raw, undecoded arguments for the specified set of system calls. The syntax of the syscall_set specification is the same as in the -e trace option. This option has the effect of causing all arguments to be printed in hexadecimal.  This is mostly useful if you don't trust the decoding or you need to know the actual numeric value of an argument. See also -X raw option.

-e read=set

-e reads=set

-e r=set

--read=set

Perform a full hexadecimal and ASCII dump of all the data read from file descriptors listed in the specified set.  For example, to see all input activity on file descriptors 3 and 5 use -e read=3,5. Note that this is independent from the normal tracing of the read(2) system call which is controlled by the option -e trace=read.

-e write=set

-e writes=set

-e w=set

--write=set

Perform a full hexadecimal and ASCII dump of all the data written to file descriptors listed in the specified set.  For example, to see all output activity on file descriptors 3 and 5 use -e write=3,5. Note that this is independent from the normal tracing of the write(2) system call which is controlled by the option -e trace=write.

-e quiet=set

-e silent=set

-e silence=set

-e q=set

--quiet=set

--silent=set

--silence=set

Suppress various information messages.  The default is quiet=none. set can include the following elements:

attach

Suppress messages about attaching and detaching ("[ Process NNNN attached ]", "[ Process NNNN detached ]").

exit

Suppress messages about process exits ("+++ exited with SSS +++").

path-resolution

Suppress messages about resolution of paths provided via the -P option ("Requested path "..." resolved into "..."").

personality

Suppress messages about process personality changes ("[ Process PID=NNNN runs in PPP mode. ]").

thread-execve

superseded

Suppress messages about process being superseded by execve(2) in another thread ("+++ superseded by execve in pid NNNN +++").

-e decode-fds=set

--decode-fds=set

Decode various information associated with file descriptors.  The default is decode-fds=none. set can include the following elements:

path

Print file paths. Also enables printing of tracee's current working directory when AT_FDCWD constant is used.

socket

Print socket protocol-specific information.

dev

Print character/block device numbers.

eventfd

Print eventfd object details associated with eventfd file descriptors.

pidfd

Print PIDs associated with pidfd file descriptors.

signalfd

Print signal masks associated with signalfd file descriptors.

-e decode-pids=set

--decode-pids=set

Decode various information associated with process IDs (and also thread IDs, process group IDs, and session IDs). The default is decode-pids=none. set can include the following elements:

comm

Print command names associated with thread or process IDs.

pidns

Print thread, process, process group, and session IDs in strace's PID namespace if the tracee is in a different PID namespace.

-e kvm=vcpu

--kvm=vcpu

Print the exit reason of kvm vcpu.  Requires Linux kernel version 4.16.0 or higher.

-i

--instruction-pointer

Print the instruction pointer at the time of the system call.

-n

--syscall-number

Print the syscall number.

-k

--stack-trace[=symbol]

Print the execution stack trace of the traced processes after each system call.

-kk

--stack-trace=source

Print the execution stack trace and source code information of the traced processes after each system call. This option expects the target program is compiled with appropriate debug options: "-g" (gcc), or "-g -gdwarf-aranges" (clang).

--stack-trace-frame-limit=limit

Print no more than this amount of stack trace frames when backtracing a system call (the default is 256). Use this option with the --stack-trace (or -k) option.

-o filename

--output=filename

Write the trace output to the file filename rather than to stderr. filename.pid form is used if -ff option is supplied. If the argument begins with '|' or '!', the rest of the argument is treated as a command and all output is piped to it. This is convenient for piping the debugging output to a program without affecting the redirections of executed programs. The latter is not compatible with -ff option currently.

-A

--output-append-mode

Open the file provided in the -o option in append mode.

-q

--quiet

--quiet=attach,personality

Suppress messages about attaching, detaching, and personality changes. This happens automatically when output is redirected to a file and the command is run directly instead of attaching.

-qq

--quiet=attach,personality,exit

Suppress messages attaching, detaching, personality changes, and about process exit status.

-qqq

--quiet=all

Suppress all suppressible messages (please refer to the -e quiet option description for the full list of suppressible messages).

-r

--relative-timestamps[=precision]

Print a relative timestamp upon entry to each system call.  This records the time difference between the beginning of successive system calls. precision can be one of s (for seconds), ms (milliseconds), us (microseconds), or ns (nanoseconds), and allows setting the precision of time value being printed. Default is us (microseconds). Note that since -r option uses the monotonic clock time for measuring time difference and not the wall clock time, its measurements can differ from the difference in time reported by the -t option.

-s strsize

--string-limit=strsize

Specify the maximum string size to print (the default is 32).  Note that filenames are not considered strings and are always printed in full.

--absolute-timestamps[=[[format:]format],[[precision:]precision]]

--timestamps[=[[format:]format],[[precision:]precision]]

Prefix each line of the trace with the wall clock time in the specified format with the specified precision. format can be one of the following:

none

No time stamp is printed. Can be used to override the previous setting.

time

Wall clock time (strftime(3) format string is %T).

unix

Number of seconds since the epoch (strftime(3) format string is %s).

precision can be one of s (for seconds), ms (milliseconds), us (microseconds), or ns (nanoseconds). Default arguments for the option are format:time,precision:s.

-t

--absolute-timestamps

Prefix each line of the trace with the wall clock time.

-tt

--absolute-timestamps=precision:us

If given twice, the time printed will include the microseconds.

-ttt

--absolute-timestamps=format:unix,precision:us

If given thrice, the time printed will include the microseconds and the leading portion will be printed as the number of seconds since the epoch.

-T

--syscall-times[=precision]

Show the time spent in system calls.  This records the time difference between the beginning and the end of each system call. precision can be one of s (for seconds), ms (milliseconds), us (microseconds), or ns (nanoseconds), and allows setting the precision of time value being printed. Default is us (microseconds).

-v

--no-abbrev

Print unabbreviated versions of environment, stat, termios, etc. calls.  These structures are very common in calls and so the default behavior displays a reasonable subset of structure members.  Use this option to get all of the gory details.

--strings-in-hex[=option]

Control usage of escape sequences with hexadecimal numbers in the printed strings. Normally (when no --strings-in-hex or -x option is supplied), escape sequences are used to print non-printable and non-ASCII characters (that is, characters with a character code less than 32 or greater than 127), or to disambiguate the output (so, for quotes and other characters that encase the printed string, for example, angle brackets, in case of file descriptor path output); for the former use case, unless it is a white space character that has a symbolic escape sequence defined in the C standard (that is, “\t” for a horizontal tab, “\n” for a newline, “\v” for a vertical tab, “\f” for a form feed page break, and “\r” for a carriage return) are printed using escape sequences with numbers that correspond to their byte values, with octal number format being the default. option can be one of the following:

none

Hexadecimal numbers are not used in the output at all. When there is a need to emit an escape sequence, octal numbers are used.

non-ascii-chars

Hexadecimal numbers are used instead of octal in the escape sequences.

non-ascii

Strings that contain non-ASCII characters are printed using escape sequences with hexadecimal numbers.

all

All strings are printed using escape sequences with hexadecimal numbers.

When the option is supplied without an argument, all is assumed.

-x

--strings-in-hex=non-ascii

Print all non-ASCII strings in hexadecimal string format.

-xx

--strings-in-hex[=all]

Print all strings in hexadecimal string format.

-X format

--const-print-style=format

Set the format for printing of named constants and flags. Supported format values are:

raw

Raw number output, without decoding.

abbrev

Output a named constant or a set of flags instead of the raw number if they are found. This is the default strace behaviour.

verbose

Output both the raw value and the decoded string (as a comment).

-y

--decode-fds

--decode-fds=path

Print paths associated with file descriptor arguments and with the AT_FDCWD constant.

-yy

--decode-fds=all

Print all available information associated with file descriptors: protocol-specific information associated with socket file descriptors, block/character device number associated with device file descriptors, and PIDs associated with pidfd file descriptors.

--pidns-translation

--decode-pids=pidns

If strace and tracee are in different PID namespaces, print PIDs in strace's namespace, too.

-Y

--decode-pids=comm

Print command names for PIDs.

--secontext[=format]

-e secontext=format

When SELinux is available and is not disabled, print in square brackets SELinux contexts of processes, files, and descriptors.  The format argument is a comma-separated list of items being one of the following:

full

Print the full context (user, role, type level and category).

mismatch

Also print the context recorded by the SELinux database in case the current context differs. The latter is printed after two exclamation marks (!!).

The default value for --secontext is !full,mismatch which prints only the type instead of full context and doesn't check for context mismatches.

--always-show-pid

Show PID prefix also for the process started by strace. Implied when -f and -o are both specified.

-c

--summary-only

Count time, calls, and errors for each system call and report a summary on program exit, suppressing the regular output. This attempts to show system time (CPU time spent running in the kernel) independent of wall clock time.  If -c is used with -f, only aggregate totals for all traced processes are kept.

-C

--summary

Like -c but also print regular output while processes are running.

-O overhead

--summary-syscall-overhead=overhead

Set the overhead for tracing system calls to overhead. This is useful for overriding the default heuristic for guessing how much time is spent in mere measuring when timing system calls using the -c option.  The accuracy of the heuristic can be gauged by timing a given program run without tracing (using time(1)) and comparing the accumulated system call time to the total produced using -c.

The format of overhead specification is described in section Time specification format description.

-S sortby

--summary-sort-by=sortby

Sort the output of the histogram printed by the -c option by the specified criterion.  Legal values are time (or time-percent or time-total or total-time), min-time (or shortest or time-min), max-time (or longest or time-max), avg-time (or time-avg), calls (or count), errors (or error), name (or syscall or syscall-name), and nothing (or none); default is time.

-U columns

--summary-columns=columns

Configure a set (and order) of columns being shown in the call summary. The columns argument is a comma-separated list with items being one of the following:

time-percent (or time)

Percentage of cumulative time consumed by a specific system call.

total-time (or time-total)

Total system (or wall clock, if -w option is provided) time consumed by a specific system call.

min-time (or shortest or time-min)

Minimum observed call duration.

max-time (or longest or time-max)

Maximum observed call duration.

avg-time (or time-avg)

Average call duration.

calls (or count)

Call count.

errors (or error)

Error count.

name (or syscall or syscall-name)

Syscall name.

The default value is time-percent,total-time,avg-time,calls,errors,name. If the name field is not supplied explicitly, it is added as the last column.

-w

--summary-wall-clock

Summarise the time difference between the beginning and end of each system call.  The default is to summarise the system time.

-e inject=syscall_set[:error=errno|:retval=value][:signal=sig][:syscall=syscall][:delay_enter=delay][:delay_exit=delay][:poke_enter=@argN=DATAN,@argM=DATAM...][:poke_exit=@argN=DATAN,@argM=DATAM...][:when=expr]

--inject=syscall_set[:error=errno|:retval=value][:signal=sig][:syscall=syscall][:delay_enter=delay][:delay_exit=delay][:poke_enter=@argN=DATAN,@argM=DATAM...][:poke_exit=@argN=DATAN,@argM=DATAM...][:when=expr]

Perform syscall tampering for the specified set of syscalls. The syntax of the syscall_set specification is the same as in the -e trace option.

At least one of error, retval, signal, delay_enter, delay_exit, poke_enter, or poke_exit options has to be specified. error and retval are mutually exclusive.

If :error=errno option is specified, a fault is injected into a syscall invocation: the syscall number is replaced by -1 which corresponds to an invalid syscall (unless a syscall is specified with :syscall= option), and the error code is specified using a symbolic errno value like ENOSYS or a numeric value within 1..4095 range.

If :retval=value option is specified, success injection is performed: the syscall number is replaced by -1, but a bogus success value is returned to the callee.

If :signal=sig option is specified with either a symbolic value like SIGSEGV or a numeric value within 1..SIGRTMAX range, that signal is delivered on entering every syscall specified by the set.

If :delay_enter=delay or :delay_exit=delay options are specified, delay injection is performed: the tracee is delayed by time period specified by delay on entering or exiting the syscall, respectively. The format of delay specification is described in section Time specification format description.

If :poke_enter=@argN=DATAN,@argM=DATAM... or :poke_exit=@argN=DATAN,@argM=DATAM... options are specified, tracee's memory at locations, pointed to by system call arguments argN and argM (going from arg1 to arg7) is overwritten by data DATAN and DATAM (specified in hexadecimal format; for example :poke_enter=@arg1=0000DEAD0000BEEF). :poke_enter modifies memory on syscall enter, and :poke_exit - on exit.

If :signal=sig option is specified without :error=errno, :retval=value or :delay_{enter,exit}=usecs options, then only a signal sig is delivered without a syscall fault or delay injection. Conversely, :error=errno or :retval=value option without :delay_enter=delay, :delay_exit=delay or :signal=sig options injects a fault without delivering a signal or injecting a delay, etc.

If :signal=sig option is specified together with :error=errno or :retval=value, then both injection of a fault or success and signal delivery are performed.

if :syscall=syscall option is specified, the corresponding syscall with no side effects is injected instead of -1. Currently, only "pure" (see -e trace=%pure description) syscalls can be specified there.

Unless a :when=expr subexpression is specified, an injection is being made into every invocation of each syscall from the set.

The format of the subexpression is:

first[..last][+[step]]

Number first stands for the first invocation number in the range, number last stands for the last invocation number in the range, and step stands for the step between two consecutive invocations. The following combinations are useful:

first

For every syscall from the set, perform an injection for the syscall invocation number first only.

first..last

For every syscall from the set, perform an injection for the syscall invocation number first and all subsequent invocations until the invocation number last (inclusive).

first+

For every syscall from the set, perform injections for the syscall invocation number first and all subsequent invocations.

first..last+

For every syscall from the set, perform injections for the syscall invocation number first and all subsequent invocations until the invocation number last (inclusive).

first+step

For every syscall from the set, perform injections for syscall invocations number first, first+step, first+step+step, and so on.

first..last+step

Same as the previous, but consider only syscall invocations with numbers up to last (inclusive).

For example, to fail each third and subsequent chdir syscalls with ENOENT, use -e inject=chdir:error=ENOENT:when=3+.

The valid range for numbers first and step is 1..65535, and for number last is 1..65534.

An injection expression can contain only one error= or retval= specification, and only one signal= specification.  If an injection expression contains multiple when= specifications, the last one takes precedence.

Accounting of syscalls that are subject to injection is done per syscall and per tracee.

Specification of syscall injection can be combined with other syscall filtering options, for example, -P /dev/urandom -e inject=file:error=ENOENT.

-e fault=syscall_set[:error=errno][:when=expr]

--fault=syscall_set[:error=errno][:when=expr]

Perform syscall fault injection for the specified set of syscalls.

This is equivalent to more generic -e inject= expression with default value of errno option set to ENOSYS.

-d

--debug

Show some debugging output of strace itself on the standard error.

-F

This option is deprecated.  It is retained for backward compatibility only and may be removed in future releases. Usage of multiple instances of -F option is still equivalent to a single -f, and it is ignored at all if used along with one or more instances of -f option.

-h

--help

Print the help summary.

--seccomp-bpf

Try to enable use of seccomp-bpf (see seccomp(2)) to have ptrace(2)-stops only when system calls that are being traced occur in the traced processes.

This option has no effect unless -f/--follow-forks is also specified. --seccomp-bpf is not compatible with --syscall-limit and -b/--detach-on options.  It is also not applicable to processes attached using -p/--attach option.

An attempt to enable system calls filtering using seccomp-bpf may fail for various reasons, e.g. there are too many system calls to filter, the seccomp API is not available, or strace itself is being traced. In cases when seccomp-bpf filter setup failed, strace proceeds as usual and stops traced processes on every system call.

When --seccomp-bpf is activated and -p/--attach option is not used, --kill-on-exit option is activated as well.

Note that in cases when the tracee has another seccomp filter that returns an action value with a precedence greater than SECCOMP_RET_TRACE, strace --seccomp-bpf will not be notified.  That is, if another seccomp filter, for example, disables the syscall or kills the tracee, then strace --seccomp-bpf will not be aware of that syscall invocation at all.

--tips[=[[id:]id],[[format:]format]]

Show strace tips, tricks, and tweaks before exit. id can be a non-negative integer number, which enables printing of specific tip, trick, or tweak (these ID are not guaranteed to be stable), or random (the default), in which case a random tip is printed. format can be one of the following:

none

No tip is printed. Can be used to override the previous setting.

compact

Print the tip just big enough to contain all the text.

full

Print the tip in its full glory.

Default is id:random,format:compact.

-V

--version

Print the version number of strace. Multiple instances of the option beyond specific threshold tend to increase Strauss awareness.

Time values can be specified as a decimal floating point number (in a format accepted by strtod(3)), optionally followed by one of the following suffices that specify the unit of time: s (seconds), ms (milliseconds), us (microseconds), or ns (nanoseconds). If no suffix is specified, the value is interpreted as microseconds.

The described format is used for -O, -e inject=delay_enter, and -e inject=delay_exit options.