- Start an interactive shell session:
- Execute a command and then exit:
fish -c "command"
- Execute a script:
- Check a script for syntax errors:
fish --no-execute path/to/script.fish
- Start an interactive shell session in private mode, where the shell does not access old history or save new history:
- Display version information and exit:
- Set and export environmental variables that persist across shell restarts (from within the shell only):
set -Ux variable_name variable_value
fish [OPTIONS] [-c command] [FILE] [ARGUMENTS...]
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 fish-tutorial(1).
The following options are available:
- -c or --command=COMMANDS evaluate the specified commands instead of reading from the commandline, passing any additional positional arguments via $argv. Note that, unlike other shells, the first argument is not the name of the program ($0), but simply the first normal argument.
- -C or --init-command=COMMANDS evaluate the specified commands after reading the configuration, before running the command specified by -c or reading interactive input
- -d or --debug=DEBUG_CATEGORIES enable debug output and specify a pattern for matching debug categories. See Debugging below for details.
- -o or --debug-output=DEBUG_FILE specify a file path to receive the debug output, including categories and fish_trace. The default is stderr.
- -i or --interactive specify that fish is to run in interactive mode
- -l or --login specify that fish is to run as a login shell
- -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 information for fish's startup to the specified file. This is useful to profile your configuration.
- -P or --private enables private mode, so fish will not access old or store new history.
- --print-rusage-self when fish exits, output stats from getrusage
- --print-debug-categories outputs the list of debug categories, and then exits.
- -v or --version display version and exit
- -f or --features=FEATURES enables one or more feature flags (separated by a comma). These are how fish stages changes that might break scripts.
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.
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