fish - Man Page

• Start an interactive shell session: fish
• Start an interactive shell session without loading startup configs: fish [-N|--no-config]
• Execute specific commands: fish [-c|--command] "echo 'fish is executed'"
• Execute a specific script: fish path/to/script.fish
• Check a specific script for syntax errors: fish [-N|--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 [-P|--private]
• Define and export an environmental variable that persists across shell restarts (builtin): set [-U|--universal] [-x|--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 <#intro> 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. Any additional positional arguments are used as $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 <#envvar-fish_trace>. The default is standard error.

-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 <#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 <#featureflags>.

The fish exit status is generally the exit status of the last foreground command <#variables-status>.

While fish provides extensive support for debugging fish scripts <#debugging>, 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 <#envvar-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 <#envvar-FISH_DEBUG> and FISH_DEBUG_OUTPUT <#envvar-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 <#envvar-FISH_DEBUG_OUTPUT>.

To just start fish:

fish

To run a file with fish:

fish /path/to/script.fish

To run some commands with fish:

fish -c 'echo Hi there!'

You can also pass arguments to those commands:

> fish -c 'printf %s\n $argv' "first line" "second line"
first line
second line

To run a script, except read this other file first:

fish --init-cmd "source otherfile" script.fish

To profile <#profiling> fish's startup and find what takes the most time in your configuration:

fish --profile-startup /tmp/start.prof -ic exit
sort -nk2 /tmp/start.prof

fish-shell developers

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