fish - Man Page

• Start an interactive shell session: fish
• Start an interactive shell session without loading startup configs: fish --no-config
• Execute specific commands: fish --command "echo 'fish is executed'"
• Execute a specific script: fish path/to/script.fish
• Check a specific script for syntax errors: fish --no-execute path/to/script.fish
• Execute specific commands from stdin: echo "echo 'fish is executed'" | fish
• Start an interactive shell session in private mode, where the shell does not access old history or save new history: fish --private
• Define and export an environmental variable that persists across shell restarts (builtin): set --universal --export variable_name variable_value

tldr.sh

fish [OPTIONS] [FILE [ARG ...]]
fish [OPTIONS] [-c COMMAND [ARG ...]]

fish is a command-line shell written mainly with interactive use in mind. This page briefly describes the options for invoking fish. The full manual is available in HTML by using the help command from inside fish, and in the fish-doc(1) man page. The tutorial is available as HTML via help tutorial or in man fish-tutorial.

The following options are available:

-c or --command=COMMAND

Evaluate the specified commands instead of reading from the commandline, passing additional positional arguments through $argv.

-C or --init-command=COMMANDS

Evaluate specified commands after reading the configuration but before executing command specified by -c or reading interactive input.

-d or --debug=DEBUG_CATEGORIES

Enables debug output and specify a pattern for matching debug categories. See Debugging below for details.

-o or --debug-output=DEBUG_FILE

Specifies a file path to receive the debug output, including categories and  fish_trace. The default is stderr.

-i or --interactive

The shell is interactive.

-l or --login

Act as if invoked as a login shell.

-N or --no-config

Do not read configuration files.

-n or --no-execute

Do not execute any commands, only perform syntax checking.

-p or --profile=PROFILE_FILE

when fish exits, output timing information on all executed commands to the specified file. This excludes time spent starting up and reading the configuration.

--profile-startup=PROFILE_FILE

Will write timing for fish startup to specified file.

-P or --private

Enables private mode: fish will not access old or store new history.

--print-rusage-self

When fish exits, output stats from getrusage.

--print-debug-categories

Print all debug categories, and then exit.

-v or --version

Print version and exit.

-f or --features=FEATURES

Enables one or more comma-separated feature flags.

The fish exit status is generally the exit status of the last foreground command.

While fish provides extensive support for debugging fish scripts, it is also possible to debug and instrument its internals. Debugging can be enabled by passing the --debug option. For example, the following command turns on debugging for background IO thread events, in addition to the default categories, i.e. debug, error, warning, and warning-path:

> fish --debug=iothread

Available categories are listed by fish --print-debug-categories. The --debug option accepts a comma-separated list of categories, and supports glob syntax. The following command turns on debugging for complete, history, history-file, and profile-history, as well as the default categories:

> fish --debug='complete,*history*'

Debug messages output to stderr by default. Note that if fish_trace is set, execution tracing also outputs to stderr by default. You can output to a file using the --debug-output option:

> fish --debug='complete,*history*' --debug-output=/tmp/fish.log --init-command='set fish_trace on'

These options can also be changed via the FISH_DEBUG and FISH_DEBUG_OUTPUT variables. The categories enabled via --debug are added to the ones enabled by $FISH_DEBUG, so they can be disabled by prefixing them with - (reader-*,-ast* enables reader debugging and disables ast debugging).

The file given in --debug-output takes precedence over the file in FISH_DEBUG_OUTPUT.

2024, fish-shell developers

env_parallel(1), podman-completion(1), systemctl(1).