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Commands

Command reference

fish ships with a large number of builtin commands, shellscript functions and external commands. These are all described below.

Almost all fish commands respond to the -h or --help options to display their relevant help, also accessible using the help and man commands, like so:

echo -h
echo --help
# Prints help to the terminal window

man echo
# Displays the man page in the system pager
# (normally 'less', 'more' or 'most').

help echo
# Open a web browser to show the relevant documentation

abbr - manage fish abbreviations

Synopsis

abbr --add word phrase...
abbr --show
abbr --list
abbr --erase word

Description

abbr manipulates the list of abbreviations that fish will expand.

Abbreviations are user-defined character sequences or words that are replaced with longer phrases after they are entered. For example, a frequently-run command such as git checkout can be abbreviated to gco. After entering gco and pressing Space or Enter, the full text git checkout will appear in the command line.

Abbreviations are stored in a variable named fish_user_abbreviations. This is automatically created as a universal variable the first time an abbreviation is created. If you want your abbreviations to be private to a particular fish session you can put the following in your *~/.config/fish/config.fish* file before you define your first abbrevation:

if status --is-interactive
    set -g fish_user_abbreviations
    abbr --add first 'echo my first abbreviation'
    abbr --add second 'echo my second abbreviation'
    # etcetera
end

You can create abbreviations directly on the command line and they will be saved automatically and made visible to other fish sessions if fish_user_abbreviations is a universal variable. If you keep the variable as universal, abbr --add statements in config.fish will do nothing but slow down startup slightly.

Options

The following parameters are available:

  • -a WORD PHRASE or --add WORD PHRASE Adds a new abbreviation, causing WORD to be expanded to PHRASE.
  • -s or --show Show all abbreviated words and their expanded phrases in a manner suitable for export and import.
  • -l or --list Lists all abbreviated words.
  • -e WORD or --erase WORD Erase the abbreviation WORD.

Note: fish version 2.1 supported -a WORD=PHRASE. This syntax is now deprecated but will still be converted.

Examples

abbr -a gco git checkout

Add a new abbreviation where gco will be replaced with git checkout.

abbr -e gco

Erase the gco abbreviation.

ssh another_host abbr -s | source

Import the abbreviations defined on another_host over SSH.

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alias - create a function

Synopsis

alias NAME DEFINITION
alias NAME=DEFINITION

Description

alias is a simple wrapper for the function builtin. It exists for backwards compatibility with Posix shells. For other uses, it is recommended to define a function.

fish does not keep track of which functions have been defined using alias. They must be erased using functions -e.

  • NAME is the name of the alias
  • DEFINITION is the actual command to execute. The string $argv will be appended.

You cannot create an alias to a function with the same name.

Note that spaces need to be escaped in the call to alias just like in the commandline even inside the quotes.

Example

The following code will create rmi, which runs rm with additional arguments on every invocation.

alias rmi "rm -i"

# This is equivalent to entering the following function:

function rmi
    rm -i $argv
end

# This needs to have the spaces escaped or "Chrome.app..." will be seen as an argument to "/Applications/Google":

alias chrome='/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome banana'

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and - conditionally execute a command

Synopsis

COMMAND1; and COMMAND2

Description

and is used to execute a command if the current exit status (as set by the previous command) is 0.

and statements may be used as part of the condition in an if or while block. See the documentation for if and while for examples.

and does not change the current exit status. The exit status of the last foreground command to exit can always be accessed using the $status variable.

Example

The following code runs the make command to build a program. If the build succeeds, make's exit status is 0, and the program is installed. If either step fails, the exit status is 1, and make clean is run, which removes the files created by the build process.

make; and make install; or make clean

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begin - start a new block of code

Synopsis

begin; [COMMANDS...;] end

Description

begin is used to create a new block of code.

The block is unconditionally executed. begin; ...; end is equivalent to if true; ...; end.

begin is used to group a number of commands into a block. This allows the introduction of a new variable scope, redirection of the input or output of a set of commands as a group, or to specify precedence when using the conditional commands like and.

begin does not change the current exit status.

Example

The following code sets a number of variables inside of a block scope. Since the variables are set inside the block and have local scope, they will be automatically deleted when the block ends.

begin
    set -l PIRATE Yarrr
    ...
end

echo $PIRATE
# This will not output anything, since the PIRATE variable
# went out of scope at the end of the block

In the following code, all output is redirected to the file out.html.

begin
    echo $xml_header
    echo $html_header
    if test -e $file
        ...
    end
    ...
end > out.html

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bg - send jobs to background

Synopsis

bg [PID...]

Description

bg sends jobs to the background, resuming them if they are stopped. A background job is executed simultaneously with fish, and does not have access to the keyboard. If no job is specified, the last job to be used is put in the background. If PID is specified, the jobs with the specified process group IDs are put in the background.

The PID of the desired process is usually found by using process expansion.

Example

bg %1 will put the job with job ID 1 in the background.

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bind - handle fish key bindings

Synopsis

bind [(-M | --mode) MODE] [(-m | --sets-mode) NEW_MODE]
     [(-k | --key)] SEQUENCE COMMAND [COMMAND...]
bind [(-M | --mode) MODE] [(-k | --key)] SEQUENCE
bind (-K | --key-names) [(-a | --all)]
bind (-f | --function-names)
bind (-e | --erase) [(-M | --mode) MODE]
     (-a | --all | [(-k | --key)] SEQUENCE [SEQUENCE...])

Description

bind adds a binding for the specified key sequence to the specified command.

SEQUENCE is the character sequence to bind to. These should be written as fish escape sequences. For example, because pressing the Alt key and another character sends that character prefixed with an escape character, Alt-based key bindings can be written using the \e escape. For example, Alt-w can be written as \ew. The control character can be written in much the same way using the \c escape, for example Control-X (^X) can be written as \cx. Note that Alt-based key bindings are case sensitive and Control-based key bindings are not. This is a constraint of text-based terminals, not fish.

The default key binding can be set by specifying a SEQUENCE of the empty string (that is, '' ). It will be used whenever no other binding matches. For most key bindings, it makes sense to use the self-insert function (i.e. bind '' self-insert) as the default keybinding. This will insert any keystrokes not specifically bound to into the editor. Non- printable characters are ignored by the editor, so this will not result in control sequences being printable.

If the -k switch is used, the name of the key (such as 'down', 'up' or 'backspace') is used instead of a sequence. The names used are the same as the corresponding curses variables, but without the 'key_' prefix. (See terminfo(5) for more information, or use bind --key-names for a list of all available named keys.)

COMMAND can be any fish command, but it can also be one of a set of special input functions. These include functions for moving the cursor, operating on the kill-ring, performing tab completion, etc. Use bind --function-names for a complete list of these input functions.

When COMMAND is a shellscript command, it is a good practice to put the actual code into a function and simply bind to the function name. This way it becomes significantly easier to test the function while editing, and the result is usually more readable as well.

If such a script produces output, the script needs to finish by calling commandline -f repaint in order to tell fish that a repaint is in order.

When multiple COMMANDs are provided, they are all run in the specified order when the key is pressed.

If no SEQUENCE is provided, all bindings (or just the bindings in the specified MODE) are printed. If SEQUENCE is provided without COMMAND, just the binding matching that sequence is printed.

Key bindings are not saved between sessions by default. Bare bind statements in config.fish won't have any effect because it is sourced before the default keybindings are setup. To save custom keybindings, put the bind statements into a function called fish_user_key_bindings, which will be autoloaded.

Key bindings may use "modes", which mimics Vi's modal input behavior. The default mode is "default", and every bind applies to a single mode. The mode can be viewed/changed with the $fish_bind_mode variable.

The following parameters are available:

  • -k or --key Specify a key name, such as 'left' or 'backspace' instead of a character sequence
  • -K or --key-names Display a list of available key names. Specifying -a or --all includes keys that don't have a known mapping
  • -f or --function-names Display a list of available input functions
  • -M MODE or --mode MODE Specify a bind mode that the bind is used in. Defaults to "default"
  • -m NEW_MODE or --sets-mode NEW_MODE Change the current mode to NEW_MODE after this binding is executed
  • -e or --erase Erase the binding with the given sequence and mode instead of defining a new one. Multiple sequences can be specified with this flag. Specifying -a or --all with -M or --mode erases all binds in the given mode regardless of sequence. Specifying -a or --all without -M or --mode erases all binds in all modes regardless of sequence.
  • -a or --all See --erase and --key-names

The following special input functions are available:

  • accept-autosuggestion, accept the current autosuggestion completely
  • backward-char, moves one character to the left
  • backward-bigword, move one whitespace-delimited word to the left
  • backward-delete-char, deletes one character of input to the left of the cursor
  • backward-kill-bigword, move the whitespace-delimited word to the left of the cursor to the killring
  • backward-kill-line, move everything from the beginning of the line to the cursor to the killring
  • backward-kill-path-component, move one path component to the left of the cursor (everything from the last "/" or whitespace exclusive) to the killring
  • backward-kill-word, move the word to the left of the cursor to the killring
  • backward-word, move one word to the left
  • beginning-of-history, move to the beginning of the history
  • beginning-of-line, move to the beginning of the line
  • begin-selection, start selecting text
  • capitalize-word, make the current word begin with a capital letter
  • complete, guess the remainder of the current token
  • complete-and-search, invoke the searchable pager on completion options
  • delete-char, delete one character to the right of the cursor
  • downcase-word, make the current word lowercase
  • end-of-history, move to the end of the history
  • end-of-line, move to the end of the line
  • end-selection, end selecting text
  • forward-bigword, move one whitespace-delimited word to the right
  • forward-char, move one character to the right
  • forward-word, move one word to the right
  • history-search-backward, search the history for the previous match
  • history-search-forward, search the history for the next match
  • kill-bigword, move the next whitespace-delimited word to the killring
  • kill-line, move everything from the cursor to the end of the line to the killring
  • kill-selection, move the selected text to the killring
  • kill-whole-line, move the line to the killring
  • kill-word, move the next word to the killring
  • suppress-autosuggestion, remove the current autosuggestion
  • swap-selection-start-stop, go to the other end of the highlighted text without changing the selection
  • transpose-chars, transpose two characters to the left of the cursor
  • transpose-words, transpose two words to the left of the cursor
  • upcase-word, make the current word uppercase
  • yank, insert the latest entry of the killring into the buffer
  • yank-pop, rotate to the previous entry of the killring

Examples

bind \cd 'exit'

Causes fish to exit when Control-D is pressed.

bind -k ppage history-search-backward

Performs a history search when the Page Up key is pressed.

set -g fish_key_bindings fish_vi_key_bindings
bind -M insert \cc kill-whole-line force-repaint

Turns on Vi key bindings and rebinds Control-C to clear the input line.

Special Case: The escape Character

The escape key can be used standalone, for example, to switch from insertion mode to normal mode when using Vi keybindings. Escape may also be used as a "meta" key, to indicate the start of an escape sequence, such as function or arrow keys. Custom bindings can also be defined that begin with an escape character.

fish waits for a period after receiving the escape character, to determine whether it is standalone or part of an escape sequence. While waiting, additional key presses make the escape key behave as a meta key. If no other key presses come in, it is handled as a standalone escape. The waiting period is set to 300 milliseconds (0.3 seconds) in the default key bindings and 10 milliseconds in the vi key bindings. It can be configured by setting the fish_escape_delay_ms variable to a value between 10 and 5000 ms. It is recommended that this be a universal variable that you set once from an interactive session.

Note: fish 2.2.0 and earlier used a default of 10 milliseconds, and provided no way to configure it. That effectively made it impossible to use escape as a meta key.

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block - temporarily block delivery of events

Synopsis

block [OPTIONS...]

Description

block prevents events triggered by fish or the emit command from being delivered and acted upon while the block is in place.

In functions, block can be useful while performing work that should not be interrupted by the shell.

The block can be removed. Any events which triggered while the block was in place will then be delivered.

Event blocks should not be confused with code blocks, which are created with begin, if, while or for

The following parameters are available:

  • -l or --local Release the block automatically at the end of the current innermost code block scope
  • -g or --global Never automatically release the lock
  • -e or --erase Release global block

Example

# Create a function that listens for events
function --on-event foo foo; echo 'foo fired'; end

# Block the delivery of events
block -g

emit foo
# No output will be produced

block -e
# 'foo fired' will now be printed

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break - stop the current inner loop

Synopsis

LOOP_CONSTRUCT; [COMMANDS...] break; [COMMANDS...] end

Description

break halts a currently running loop, such as a for loop or a while loop. It is usually added inside of a conditional block such as an if statement or a switch statement.

There are no parameters for break.

Example

The following code searches all .c files for "smurf", and halts at the first occurrence.

for i in *.c
    if grep smurf $i
        echo Smurfs are present in $i
        break
    end
end

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breakpoint - Launch debug mode

Synopsis

breakpoint

Description

breakpoint is used to halt a running script and launch an interactive debugging prompt.

For more details, see Debugging fish scripts in the fish manual.

There are no parameters for breakpoint.

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builtin - run a builtin command

Synopsis

builtin BUILTINNAME [OPTIONS...]

Description

builtin forces the shell to use a builtin command, rather than a function or program.

The following parameters are available:

  • -n or --names List the names of all defined builtins

Example

builtin jobs
# executes the jobs builtin, even if a function named jobs exists

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case - conditionally execute a block of commands

Synopsis

switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end

Description

switch performs one of several blocks of commands, depending on whether a specified value equals one of several wildcarded values. case is used together with the switch statement in order to determine which block should be executed.

Each case command is given one or more parameters. The first case command with a parameter that matches the string specified in the switch command will be evaluated. case parameters may contain wildcards. These need to be escaped or quoted in order to avoid regular wildcard expansion using filenames.

Note that fish does not fall through on case statements. Only the first matching case is executed.

Note that command substitutions in a case statement will be evaluated even if its body is not taken. All substitutions, including command substitutions, must be performed before the value can be compared against the parameter.

Example

If the variable $animal contains the name of an animal, the following code would attempt to classify it:

switch $animal
    case cat
        echo evil
    case wolf dog human moose dolphin whale
        echo mammal
    case duck goose albatross
        echo bird
    case shark trout stingray
        echo fish
    # Note that the next case has a wildcard which is quoted
    case '*'
        echo I have no idea what a $animal is
end

If the above code was run with $animal set to whale, the output would be mammal.

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cd - change directory

Synopsis

cd [DIRECTORY]

Description

cd changes the current working directory.

If DIRECTORY is supplied, it will become the new directory. If no parameter is given, the contents of the HOME environment variable will be used.

If DIRECTORY is a relative path, the paths found in the CDPATH environment variable array will be tried as prefixes for the specified path.

Note that the shell will attempt to change directory without requiring cd if the name of a directory is provided (starting with ., / or ~, or ending with /).

Fish also ships a wrapper function around the builtin cd that understands cd - as changing to the previous directory. See also prevd. This wrapper function maintains a history of the 25 most recently visited directories in the $dirprev and $dirnext global variables.

Examples

cd
# changes the working directory to your home directory.

cd /usr/src/fish-shell
# changes the working directory to /usr/src/fish-shell

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command - run a program

Synopsis

command [OPTIONS] COMMANDNAME [ARGS...]

Description

command forces the shell to execute the program COMMANDNAME and ignore any functions or builtins with the same name.

The following options are available:

  • -s or --search returns the name of the disk file that would be executed, or nothing if no file with the specified name could be found in the $PATH.

With the -s option, command treats every argument as a separate command to look up and sets the exit status to 0 if any of the specified commands were found, or 1 if no commands could be found.

For basic compatibility with POSIX command, the -v flag is recognized as an alias for -s.

Examples

command ls causes fish to execute the ls program, even if an ls function exists.

command -s ls returns the path to the ls program.

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commandline - set or get the current command line buffer

Synopsis

commandline [OPTIONS] [CMD]

Description

commandline can be used to set or get the current contents of the command line buffer.

With no parameters, commandline returns the current value of the command line.

With CMD specified, the command line buffer is erased and replaced with the contents of CMD.

The following options are available:

  • -C or --cursor set or get the current cursor position, not the contents of the buffer. If no argument is given, the current cursor position is printed, otherwise the argument is interpreted as the new cursor position.
  • -f or --function inject readline functions into the reader. This option cannot be combined with any other option. It will cause any additional arguments to be interpreted as readline functions, and these functions will be injected into the reader, so that they will be returned to the reader before any additional actual key presses are read.

The following options change the way commandline updates the command line buffer:

  • -a or --append do not remove the current commandline, append the specified string at the end of it
  • -i or --insert do not remove the current commandline, insert the specified string at the current cursor position
  • -r or --replace remove the current commandline and replace it with the specified string (default)

The following options change what part of the commandline is printed or updated:

  • -b or --current-buffer select the entire buffer (default)
  • -j or --current-job select the current job
  • -p or --current-process select the current process
  • -t or --current-token select the current token.

The following options change the way commandline prints the current commandline buffer:

  • -c or --cut-at-cursor only print selection up until the current cursor position
  • -o or --tokenize tokenize the selection and print one string-type token per line

If commandline is called during a call to complete a given string using complete -C STRING, commandline will consider the specified string to be the current contents of the command line.

The following options output metadata about the commandline state:

  • -L or --line print the line that the cursor is on, with the topmost line starting at 1
  • -S or --search-mode evaluates to true if the commandline is performing a history search
  • -P or --paging-mode evaluates to true if the commandline is showing pager contents, such as tab completions

Example

commandline -j $history[3] replaces the job under the cursor with the third item from the command line history.

If the commandline contains

> echo $flounder >&2 | less; and echo $catfish

(with the cursor on the "o" of "flounder")

Then the following invocations behave like this:

> commandline -t
$flounder
> commandline -ct
$fl
> commandline -b ## or just commandline
echo $flounder >&2 | less; and echo $catfish
> commandline -p
echo $flounder >&2
> commandline -j
echo $flounder >&2 | less

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complete - edit command specific tab-completions

Synopsis

complete ( -c | --command | -p | --path ) COMMAND
        [( -c | --command | -p | --path ) COMMAND]...
        [( -e | --erase )]
        [( -s | --short-option ) SHORT_OPTION]...
        [( -l | --long-option | -o | --old-option ) LONG_OPTION]...
        [( -a | --arguments ) OPTION_ARGUMENTS]
        [( -f | --no-files )]
        [( -r | --require-parameter )]
        [( -x | --exclusive )]
        [( -w | --wraps ) WRAPPED_COMMAND]...
        [( -n | --condition ) CONDITION]
        [( -d | --description ) DESCRIPTION]
complete ( -C[STRING] | --do-complete[=STRING] )

Description

For an introduction to specifying completions, see Writing your own completions in the fish manual.

  • COMMAND is the name of the command for which to add a completion.
  • SHORT_OPTION is a one character option for the command.
  • LONG_OPTION is a multi character option for the command.
  • OPTION_ARGUMENTS is parameter containing a space-separated list of possible option-arguments, which may contain command substitutions.
  • DESCRIPTION is a description of what the option and/or option arguments do.
  • -c COMMAND or --command COMMAND specifies that COMMAND is the name of the command.
  • -p COMMAND or --path COMMAND specifies that COMMAND is the absolute path of the program (optionally containing wildcards).
  • -e or --erase deletes the specified completion.
  • -s SHORT_OPTION or --short-option=SHORT_OPTION adds a short option to the completions list.
  • -l LONG_OPTION or --long-option=LONG_OPTION adds a GNU style long option to the completions list.
  • -o LONG_OPTION or --old-option=LONG_OPTION adds an old style long option to the completions list (See below for details).
  • -a OPTION_ARGUMENTS or --arguments=OPTION_ARGUMENTS adds the specified option arguments to the completions list.
  • -f or --no-files specifies that the options specified by this completion may not be followed by a filename.
  • -r or --require-parameter specifies that the options specified by this completion always must have an option argument, i.e. may not be followed by another option.
  • -x or --exclusive implies both -r and -f.
  • -w WRAPPED_COMMAND or --wraps=WRAPPED_COMMAND causes the specified command to inherit completions from the wrapped command (See below for details).
  • -n or --condition specifies a shell command that must return 0 if the completion is to be used. This makes it possible to specify completions that should only be used in some cases.
  • -CSTRING or --do-complete=STRING makes complete try to find all possible completions for the specified string.
  • -C or --do-complete with no argument makes complete try to find all possible completions for the current command line buffer. If the shell is not in interactive mode, an error is returned.

Command specific tab-completions in fish are based on the notion of options and arguments. An option is a parameter which begins with a hyphen, such as '-h', '-help' or '--help'. Arguments are parameters that do not begin with a hyphen. Fish recognizes three styles of options, the same styles as the GNU version of the getopt library. These styles are:

  • Short options, like '-a'. Short options are a single character long, are preceded by a single hyphen and may be grouped together (like '-la', which is equivalent to '-l -a'). Option arguments may be specified in the following parameter ('-w 32') or by appending the option with the value ('-w32').
  • Old style long options, like '-Wall'. Old style long options can be more than one character long, are preceded by a single hyphen and may not be grouped together. Option arguments are specified in the following parameter ('-ao null').
  • GNU style long options, like '--colors'. GNU style long options can be more than one character long, are preceded by two hyphens, and may not be grouped together. Option arguments may be specified in the following parameter ('--quoting-style shell') or by appending the option with a '=' and the value ('--quoting-style=shell'). GNU style long options may be abbreviated so long as the abbreviation is unique ('--h') is equivalent to '--help' if help is the only long option beginning with an 'h').

The options for specifying command name and command path may be used multiple times to define the same completions for multiple commands.

The options for specifying command switches and wrapped commands may be used multiple times to define multiple completions for the command(s) in a single call.

Invoking complete multiple times for the same command adds the new definitions on top of any existing completions defined for the command.

When -a or --arguments is specified in conjunction with long, short, or old style options, the specified arguments are only used as completions when attempting to complete an argument for any of the specified options. If -a or --arguments is specified without any long, short, or old style options, the specified arguments are used when completing any argument to the command (except when completing an option argument that was specified with -r or --require-parameter).

Command substitutions found in OPTION_ARGUMENTS are not expected to return a space-separated list of arguments. Instead they must return a newline-separated list of arguments, and each argument may optionally have a tab character followed by the argument description. Any description provided in this way overrides a description given with -d or --description.

The -w or --wraps options causes the specified command to inherit completions from another command. The inheriting command is said to "wrap" the inherited command. The wrapping command may have its own completions in addition to inherited ones. A command may wrap multiple commands, and wrapping is transitive: if A wraps B, and B wraps C, then A automatically inherits all of C's completions. Wrapping can be removed using the -e or --erase options. Note that wrapping only works for completions specified with -c or --command and are ignored when specifying completions with -p or --path.

When erasing completions, it is possible to either erase all completions for a specific command by specifying complete -c COMMAND -e, or by specifying a specific completion option to delete by specifying either a long, short or old style option.

Example

The short style option -o for the gcc command requires that a file follows it. This can be done using writing:

complete -c gcc -s o -r

The short style option -d for the grep command requires that one of the strings 'read', 'skip' or 'recurse' is used. This can be specified writing:

complete -c grep -s d -x -a "read skip recurse"

The su command takes any username as an argument. Usernames are given as the first colon-separated field in the file /etc/passwd. This can be specified as:

complete -x -c su -d "Username" -a "(cat /etc/passwd | cut -d : -f 1)"

The rpm command has several different modes. If the -e or --erase flag has been specified, rpm should delete one or more packages, in which case several switches related to deleting packages are valid, like the nodeps switch.

This can be written as:

complete -c rpm -n "__fish_contains_opt -s e erase" -d nodeps "Don't check dependencies"

where __fish_contains_opt is a function that checks the command line buffer for the presence of a specified set of options.

To implement an alias, use the -w or --wraps option:

complete -c hub -w git

Now hub inherits all of the completions from git. Note this can also be specified in a function declaration.

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contains - test if a word is present in a list

Synopsis

contains [OPTIONS] KEY [VALUES...]

Description

contains tests whether the set VALUES contains the string KEY. If so, contains exits with status 0; if not, it exits with status 1.

The following options are available:

  • -i or --index print the word index

Note that, like GNU tools, contains interprets all arguments starting with a - as options to contains, until it reaches an argument that is -- (two dashes). See the examples below.

Example

for i in ~/bin /usr/local/bin
    if not contains $i $PATH
        set PATH $PATH $i
    end
end

The above code tests if ~/bin and /usr/local/bin are in the path and adds them if not.

function hasargs
    if contains -- -q $argv
        echo '$argv contains a -q option'
    end
end

The above code checks for -q in the argument list, using the -- argument to demarcate options to contains from the key to search for.

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continue - skip the remainder of the current iteration of the current inner loop

Synopsis

LOOP_CONSTRUCT; [COMMANDS...;] continue; [COMMANDS...;] end

Description

continue skips the remainder of the current iteration of the current inner loop, such as a for loop or a while loop. It is usually added inside of a conditional block such as an if statement or a switch statement.

Example

The following code removes all tmp files that do not contain the word smurf.

for i in *.tmp
    if grep smurf $i
        continue
    end
    rm $i
end

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count - count the number of elements of an array

Synopsis

count $VARIABLE

Description

count prints the number of arguments that were passed to it. This is usually used to find out how many elements an environment variable array contains.

count does not accept any options, including -h or --help.

count exits with a non-zero exit status if no arguments were passed to it, and with zero if at least one argument was passed.

Example

count $PATH
# Returns the number of directories in the users PATH variable.

count *.txt
# Returns the number of files in the current working directory ending with the suffix '.txt'.

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dirh - print directory history

Synopsis

dirh

Description

dirh prints the current directory history. The current position in the history is highlighted using the color defined in the fish_color_history_current environment variable.

dirh does not accept any parameters.

Note that the cd command limits directory history to the 25 most recently visited directories. The history is stored in the $dirprev and $dirnext variables.

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dirs - print directory stack

Synopsis

dirs
dirs -c

Description

dirs prints the current directory stack, as created by the pushd command.

With "-c", it clears the directory stack instead.

dirs does not accept any parameters.

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echo - display a line of text

Synopsis

echo [OPTIONS] [STRING]

Description

echo displays a string of text.

The following options are available:

  • -n, Do not output a newline
  • -s, Do not separate arguments with spaces
  • -E, Disable interpretation of backslash escapes (default)
  • -e, Enable interpretation of backslash escapes

Escape Sequences

If -e is used, the following sequences are recognized:

  • \ backslash
  • \a alert (BEL)
  • \b backspace
  • \c produce no further output
  • \e escape
  • \f form feed
  • \n new line
  • \r carriage return
  • \t horizontal tab
  • \v vertical tab
  • \0NNN byte with octal value NNN (1 to 3 digits)
  • \xHH byte with hexadecimal value HH (1 to 2 digits)

Example

echo 'Hello World'

Print hello world to stdout

echo -e 'Top\nBottom'

Print Top and Bottom on separate lines, using an escape sequence

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else - execute command if a condition is not met

Synopsis

if CONDITION; COMMANDS_TRUE...; [else; COMMANDS_FALSE...;] end

Description

if will execute the command CONDITION. If the condition's exit status is 0, the commands COMMANDS_TRUE will execute. If it is not 0 and else is given, COMMANDS_FALSE will be executed.

Example

The following code tests whether a file foo.txt exists as a regular file.

if test -f foo.txt
    echo foo.txt exists
else
    echo foo.txt does not exist
end

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emit - Emit a generic event

Synopsis

emit EVENT_NAME [ARGUMENTS...]

Description

emit emits, or fires, an event. Events are delivered to, or caught by, special functions called event handlers. The arguments are passed to the event handlers as function arguments.

Example

The following code first defines an event handler for the generic event named 'test_event', and then emits an event of that type.

function event_test --on-event test_event
    echo event test: $argv
end

emit test_event something

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end - end a block of commands.

Synopsis

begin; [COMMANDS...] end
if CONDITION; COMMANDS_TRUE...; [else; COMMANDS_FALSE...;] end
while CONDITION; COMMANDS...; end
for VARNAME in [VALUES...]; COMMANDS...; end
switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end

Description

end ends a block of commands.

For more information, read the documentation for the block constructs, such as if, for and while.

The end command does not change the current exit status.

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eval - evaluate the specified commands

Synopsis

eval [COMMANDS...]

Description

eval evaluates the specified parameters as a command. If more than one parameter is specified, all parameters will be joined using a space character as a separator.

Example

The following code will call the ls command. Note that fish does not support the use of shell variables as direct commands; eval can be used to work around this.

set cmd ls
eval $cmd

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exec - execute command in current process

Synopsis

exec COMMAND [OPTIONS...]

Description

exec replaces the currently running shell with a new command. On successful completion, exec never returns. exec cannot be used inside a pipeline.

Example

exec emacs starts up the emacs text editor, and exits fish. When emacs exits, the session will terminate.

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exit - exit the shell

Synopsis

exit [STATUS]

Description

exit causes fish to exit. If STATUS is supplied, it will be converted to an integer and used as the exit code. Otherwise, the exit code will be that of the last command executed.

If exit is called while sourcing a file (using the source builtin) the rest of the file will be skipped, but the shell itself will not exit.

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false - return an unsuccessful result

Synopsis

false

Description

false sets the exit status to 1.

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fg - bring job to foreground

Synopsis

fg [PID]

Description

fg brings the specified job to the foreground, resuming it if it is stopped. While a foreground job is executed, fish is suspended. If no job is specified, the last job to be used is put in the foreground. If PID is specified, the job with the specified group ID is put in the foreground.

The PID of the desired process is usually found by using process expansion. Fish is capable of expanding far more than just the numeric PID, including referencing itself and finding PIDs by name.

Example

fg %1 will put the job with job ID 1 in the foreground.

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fish - the friendly interactive shell

Synopsis

fish [OPTIONS] [-c command] [FILE [ARGUMENTS...]]

Description

fish is a command-line shell written mainly with interactive use in mind. The full manual is available in HTML by using the help command from inside fish.

The following options are available:

  • -c or --command=COMMANDS evaluate the specified commands instead of reading from the commandline
  • -d or --debug-level=DEBUG_LEVEL specify the verbosity level of fish. A higher number means higher verbosity. The default level is 1.
  • -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
  • -v or --version display version and exit
  • -D or --debug-stack-frames=DEBUG_LEVEL specify how many stack frames to display when debug messages are written. The default is zero. A value of 3 or 4 is usually sufficient to gain insight into how a given debug call was reached but you can specify a value up to 128.

The fish exit status is generally the exit status of the last foreground command. If fish is exiting because of a parse error, the exit status is 127.

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fish_config - start the web-based configuration interface

Description

fish_config starts the web-based configuration interface.

The web interface allows you to view your functions, variables and history, and to make changes to your prompt and color configuration.

fish_config starts a local web server and then opens a web browser window; when you have finished, close the browser window and then press the Enter key to terminate the configuration session.

fish_config optionally accepts name of the initial configuration tab. For e.g. fish_config history will start configuration interface with history tab.

If the BROWSER environment variable is set, it will be used as the name of the web browser to open instead of the system default.

Example

fish_config opens a new web browser window and allows you to configure certain fish settings.

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fish_indent - indenter and prettifier

Synopsis

fish_indent [OPTIONS]

Description

fish_indent is used to indent a piece of fish code. fish_indent reads commands from standard input and outputs them to standard output or a specified file.

The following options are available:

  • -w or --write indents a specified file and immediately writes to that file.
  • -i or --no-indent do not indent commands; only reformat to one job per line.
  • -v or --version displays the current fish version and then exits.
  • --ansi colorizes the output using ANSI escape sequences, appropriate for the current $TERM, using the colors defined in the environment (such as $fish_color_command).
  • --html outputs HTML, which supports syntax highlighting if the appropriate CSS is defined. The CSS class names are the same as the variable names, such as fish_color_command.
  • -d or --debug-level=DEBUG_LEVEL enables debug output and specifies a verbosity level (like fish -d). Defaults to 0.
  • -D or --debug-stack-frames=DEBUG_LEVEL specify how many stack frames to display when debug messages are written. The default is zero. A value of 3 or 4 is usually sufficient to gain insight into how a given debug call was reached but you can specify a value up to 128.
  • --dump-parse-tree dumps information about the parsed statements to stderr. This is likely to be of interest only to people working on the fish source code.

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fish_key_reader - explore what characters keyboard keys send

Synopsis

fish_key_reader [OPTIONS]

Description

fish_key_reader is used to study input received from the terminal and can help with key binds. The program is interactive and works on standard input. Individual characters themselves and their hexadecimal values are displayed.

The tool will write an example bind command matching the character sequence captured to stdout. If the character sequence matches a special key name (see bind --key-names), both bind CHARS ... and bind -k KEYNAME ... usage will be shown. Additional details about the characters received, such as the delay between chars, are written to stderr.

The following options are available:

  • -c or --continuous begins a session where multiple key sequences can be inspected. By default the program exits after capturing a single key sequence.
  • -d or --debug-level=DEBUG_LEVEL enables debug output and specifies a verbosity level (like fish -d). Defaults to 0.
  • -D or --debug-stack-frames=DEBUG_LEVEL specify how many stack frames to display when debug messages are written. The default is zero. A value of 3 or 4 is usually sufficient to gain insight into how a given debug call was reached but you can specify a value up to 128.
  • -h or --help prints usage information.

Usage Notes

The delay in milliseconds since the previous character was received is included in the diagnostic information written to stderr. This information may be useful to determine the optimal fish_escape_delay_ms setting or learn the amount of lag introduced by tools like ssh, mosh or tmux.

fish_key_reader intentionally disables handling of many signals. To terminate fish_key_reader in --continuous mode do:

  • press Ctrl-C twice, or
  • press Ctrl-D twice, or
  • type exit, or
  • type quit

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fish_mode_prompt - define the appearance of the mode indicator

Synopsis

fish_mode_prompt will output the mode indicator for use in vi-mode.

Description

The output of fish_mode_prompt will be displayed in the mode indicator position to the left of the regular prompt.

Multiple lines are not supported in fish_mode_prompt.

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fish_prompt - define the appearance of the command line prompt

Synopsis

function fish_prompt
    ...
end

Description

By defining the fish_prompt function, the user can choose a custom prompt. The fish_prompt function is executed when the prompt is to be shown, and the output is used as a prompt.

The exit status of commands within fish_prompt will not modify the value of $status outside of the fish_prompt function.

fish ships with a number of example prompts that can be chosen with the fish_config command.

Example

A simple prompt:

function fish_prompt -d "Write out the prompt"
    printf '%s@%s%s%s%s> ' (whoami) (hostname | cut -d . -f 1) \ 
            (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
end

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fish_right_prompt - define the appearance of the right-side command line prompt

Synopsis

function fish_right_prompt
    ...
end

Description

fish_right_prompt is similar to fish_prompt, except that it appears on the right side of the terminal window.

Multiple lines are not supported in fish_right_prompt.

Example

A simple right prompt:

function fish_right_prompt -d "Write out the right prompt"
    date '+%m/%d/%y'
end

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fish_update_completions - Update completions using manual pages

Description

fish_update_completions parses manual pages installed on the system, and attempts to create completion files in the fish configuration directory.

This does not overwrite custom completions.

There are no parameters for fish_update_completions.

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fish_vi_mode - Enable vi mode

Synopsis

fish_vi_mode

Description

This function is deprecated. Please call fish_vi_key_bindings directly

fish_vi_mode enters a vi-like command editing mode. To always start in vi mode, add fish_vi_mode to your config.fish file.

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for - perform a set of commands multiple times.

Synopsis

for VARNAME in [VALUES...]; COMMANDS...; end

Description

for is a loop construct. It will perform the commands specified by COMMANDS multiple times. On each iteration, the local variable specified by VARNAME is assigned a new value from VALUES. If VALUES is empty, COMMANDS will not be executed at all.

Example

for i in foo bar baz; echo $i; end

# would output:
foo
bar
baz

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funced - edit a function interactively

Synopsis

funced [OPTIONS] NAME

Description

funced provides an interface to edit the definition of the function NAME.

If the $VISUAL environment variable is set, it will be used as the program to edit the function. If $VISUAL is unset but $EDITOR is set, that will be used. Otherwise, a built-in editor will be used.

If there is no function called NAME a new function will be created with the specified name

  • -e command or --editor command Open the function body inside the text editor given by the command (for example, "vi"). The command 'fish' will use the built-in editor.
  • -i or --interactive Open function body in the built-in editor.

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funcsave - save the definition of a function to the user's autoload directory

Synopsis

funcsave FUNCTION_NAME

Description

funcsave saves the current definition of a function to a file in the fish configuration directory. This function will be automatically loaded by current and future fish sessions. This can be useful if you have interactively created a new function and wish to save it for later use.

Note that because fish loads functions on-demand, saved functions will not function as event handlers until they are run or sourced otherwise. To activate an event handler for every new shell, add the function to your shell initialization file instead of using funcsave.

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function - create a function

Synopsis

function NAME [OPTIONS]; BODY; end

Description

function creates a new function NAME with the body BODY.

A function is a list of commands that will be executed when the name of the function is given as a command.

The following options are available:

  • -a NAMES or --argument-names NAMES assigns the value of successive command-line arguments to the names given in NAMES.
  • -d DESCRIPTION or --description=DESCRIPTION is a description of what the function does, suitable as a completion description.
  • -w WRAPPED_COMMAND or --wraps=WRAPPED_COMMAND causes the function to inherit completions from the given wrapped command. See the documentation for complete for more information.
  • -e or --on-event EVENT_NAME tells fish to run this function when the specified named event is emitted. Fish internally generates named events e.g. when showing the prompt.
  • -v or --on-variable VARIABLE_NAME tells fish to run this function when the variable VARIABLE_NAME changes value.
  • -j PGID or --on-job-exit PGID tells fish to run this function when the job with group ID PGID exits. Instead of PGID, the string 'caller' can be specified. This is only legal when in a command substitution, and will result in the handler being triggered by the exit of the job which created this command substitution.
  • -p PID or --on-process-exit PID tells fish to run this function when the fish child process with process ID PID exits.
  • -s or --on-signal SIGSPEC tells fish to run this function when the signal SIGSPEC is delivered. SIGSPEC can be a signal number, or the signal name, such as SIGHUP (or just HUP).
  • -S or --no-scope-shadowing allows the function to access the variables of calling functions. Normally, any variables inside the function that have the same name as variables from the calling function are "shadowed", and their contents is independent of the calling function.
  • -V or --inherit-variable NAME snapshots the value of the variable NAME and defines a local variable with that same name and value when the function is executed.

If the user enters any additional arguments after the function, they are inserted into the environment variable array $argv. If the --argument-names option is provided, the arguments are also assigned to names specified in that option.

By using one of the event handler switches, a function can be made to run automatically at specific events. The user may generate new events using the emit builtin. Fish generates the following named events:

  • fish_prompt, which is emitted whenever a new fish prompt is about to be displayed.
  • fish_command_not_found, which is emitted whenever a command lookup failed.
  • fish_preexec, which is emitted right before executing an interactive command. The commandline is passed as the first parameter.

    Note: This event will be emitted even if the command is invalid. The commandline parameter includes the entire commandline verbatim, and may potentially include newlines.

  • fish_postexec, which is emitted right after executing an interactive command. The commandline is passed as the first parameter.

    Note: This event will be emitted even if the command is invalid. The commandline parameter includes the entire commandline verbatim, and may potentially include newlines.

Example

function ll
    ls -l $argv
end

will run the ls command, using the -l option, while passing on any additional files and switches to ls.

function mkdir -d "Create a directory and set CWD"
    command mkdir $argv
    if test $status = 0
        switch $argv[(count $argv)]
            case '-*'

            case '*'
                cd $argv[(count $argv)]
                return
        end
    end
end

This will run the mkdir command, and if it is successful, change the current working directory to the one just created.

function notify
    set -l job (jobs -l -g)
    or begin; echo "There are no jobs" >&2; return 1; end

    function _notify_job_$job --on-job-exit $job --inherit-variable job
        echo -n \a ## beep
        functions -e _notify_job_$job
    end
end

This will beep when the most recent job completes.

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functions - print or erase functions

Synopsis

functions [ -a | --all ] [ -n | --names ]
functions -c OLDNAME NEWNAME
functions -d DESCRIPTION FUNCTION
functions [ -e | -q ] FUNCTIONS...

Description

functions prints or erases functions.

The following options are available:

  • -a or --all lists all functions, even those whose name start with an underscore.
  • -c OLDNAME NEWNAME or --copy OLDNAME NEWNAME creates a new function named NEWNAME, using the definition of the OLDNAME function.
  • -d DESCRIPTION or --description=DESCRIPTION changes the description of this function.
  • -e or --erase causes the specified functions to be erased.
  • -n or --names lists the names of all defined functions.
  • -q or --query tests if the specified functions exist.

The default behavior of functions, when called with no arguments, is to print the names of all defined functions. Unless the -a option is given, no functions starting with underscores are not included in the output.

If any non-option parameters are given, the definition of the specified functions are printed.

Automatically loaded functions cannot be removed using functions -e. Either remove the definition file or change the $fish_function_path variable to remove autoloaded functions.

Copying a function using -c copies only the body of the function, and does not attach any event notifications from the original function.

Only one function's description can be changed in a single invocation of functions -d.

The exit status of functions is the number of functions specified in the argument list that do not exist, which can be used in concert with the -q option.

Examples

functions -n
# Displays a list of currently-defined functions

functions -c foo bar
# Copies the 'foo' function to a new function called 'bar'

functions -e bar
# Erases the function `bar`

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help - display fish documentation

Synopsis

help [SECTION]

Description

help displays the fish help documentation.

If a SECTION is specified, the help for that command is shown.

If the BROWSER environment variable is set, it will be used to display the documentation. Otherwise, fish will search for a suitable browser.

Note that most builtin commands display their help in the terminal when given the --help option.

Example

help fg shows the documentation for the fg builtin.

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history - Show and manipulate command history

Synopsis

history search [ --show-time ] [ --case-sensitive ] [ --exact | --prefix | --contains ] [ --max=n ] [ --null ] [ "search string"... ]
history delete [ --show-time ] [ --case-sensitive ] [ --exact | --prefix | --contains ] "search string"...
history merge
history save
history clear
history ( -h | --help )

Description

history is used to search, delete, and otherwise manipulate the history of interactive commands.

Note that for backwards compatibility each subcommand can also be specified as a long option. For example, rather than history search you can type history --search. Those long options are deprecated and will be removed in a future release.

The following operations (sub-commands) are available:

  • search returns history items matching the search string. If no search string is provided it returns all history items. This is the default operation if no other operation is specified. You only have to explicitly say history search if you wish to search for one of the subcommands. The --contains search option will be used if you don't specify a different search option. Entries are ordered newest to oldest. If stdout is attached to a tty the output will be piped through your pager by the history function. The history builtin simply writes the results to stdout.
  • delete deletes history items. Without the --prefix or --contains options, the exact match of the specified text will be deleted. If you don't specify --exact a prompt will be displayed before any items are deleted asking you which entries are to be deleted. You can enter the word "all" to delete all matching entries. You can enter a single ID (the number in square brackets) to delete just that single entry. You can enter more than one ID separated by a space to delete multiple entries. Just press [enter] to not delete anything. Note that the interactive delete behavior is a feature of the history function. The history builtin only supports --exact --case-sensitive deletion.
  • merge immediately incorporates history changes from other sessions. Ordinarily fish ignores history changes from sessions started after the current one. This command applies those changes immediately.
  • save immediately writes all changes to the history file. The shell automatically saves the history file; this option is provided for internal use and should not normally need to be used by the user.
  • clear clears the history file. A prompt is displayed before the history is erased asking you to confirm you really want to clear all history unless builtin history is used.

The following options are available:

These flags can appear before or immediately after one of the sub-commands listed above.

  • -C or --case-sensitive does a case-sensitive search. The default is case-insensitive. Note that prior to fish 2.4.0 the default was case-sensitive.
  • -c or --contains searches or deletes items in the history that contain the specified text string. This is the default for the --search flag. This is not currently supported by the --delete flag.
  • -e or --exact searches or deletes items in the history that exactly match the specified text string. This is the default for the --delete flag. Note that the match is case-insensitive by default. If you really want an exact match, including letter case, you must use the -C or --case-sensitive flag.
  • -p or --prefix searches or deletes items in the history that begin with the specified text string. This is not currently supported by the --delete flag.
  • -t or --show-time prepends each history entry with the date and time the entry was recorded . By default it uses the strftime format # cn. You can specify another format; e.g., `–show-time='Y-m-d H:M:S 'or–show-time='aIp'. The short option,-tdoesn't accept a stftime format string; it only uses the default format. Any strftime format is allowed, includingsto get the raw UNIX seconds since the epoch. Note that–with-time` is also allowed but is deprecated and will be removed at a future date.
  • -z or --null causes history entries written by the search operations to be terminated by a NUL character rather than a newline. This allows the output to be processed by read -z to correctly handle multiline history entries.
  • -<number> -n <number> or --max=<number> limits the matched history items to the first "n" matching entries. This is only valid for history search.
  • -h or --help display help for this command.

Example

history --clear
# Deletes all history items

history --search --contains "foo"
# Outputs a list of all previous commands containing the string "foo".

history --delete --prefix "foo"
# Interactively deletes commands which start with "foo" from the history.
# You can select more than one entry by entering their IDs seperated by a space.

\subsection history-notes Notes

If you specify both `--prefix` and `--contains` the last flag seen is used.

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if - conditionally execute a command

Synopsis

if CONDITION; COMMANDS_TRUE...;
[else if CONDITION2; COMMANDS_TRUE2...;]
[else; COMMANDS_FALSE...;]
end

Description

if will execute the command CONDITION. If the condition's exit status is 0, the commands COMMANDS_TRUE will execute. If the exit status is not 0 and else is given, COMMANDS_FALSE will be executed.

You can use and or or in the condition. See the second example below.

The exit status of the last foreground command to exit can always be accessed using the $status variable.

Example

The following code will print foo.txt exists if the file foo.txt exists and is a regular file, otherwise it will print bar.txt exists if the file bar.txt exists and is a regular file, otherwise it will print foo.txt and bar.txt do not exist.

if test -f foo.txt
    echo foo.txt exists
else if test -f bar.txt
    echo bar.txt exists
else
    echo foo.txt and bar.txt do not exist
end

The following code will print "foo.txt exists and is readable" if foo.txt is a regular file and readable

if test -f foo.txt
   and test -r foo.txt
   echo "foo.txt exists and is readable"
end

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isatty - test if a file descriptor is a tty.

Synopsis

isatty [FILE DESCRIPTOR]

Description

isatty tests if a file descriptor is a tty.

FILE DESCRIPTOR may be either the number of a file descriptor, or one of the strings stdin, stdout, or stderr.

If the specified file descriptor is a tty, the exit status of the command is zero. Otherwise, the exit status is non-zero. No messages are printed to standard error.

Examples

From an interactive shell, the commands below exit with a return value of zero:

isatty
isatty stdout
isatty 2
echo | isatty 1

And these will exit non-zero:

echo | isatty
isatty 9
isatty stdout > file
isatty 2 2> file

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jobs - print currently running jobs

Synopsis

jobs [OPTIONS] [PID]

Description

jobs prints a list of the currently running jobs and their status.

jobs accepts the following switches:

  • -c or --command prints the command name for each process in jobs.
  • -g or --group only prints the group ID of each job.
  • -l or --last prints only the last job to be started.
  • -p or --pid prints the process ID for each process in all jobs.

On systems that supports this feature, jobs will print the CPU usage of each job since the last command was executed. The CPU usage is expressed as a percentage of full CPU activity. Note that on multiprocessor systems, the total activity may be more than 100%.

Example

jobs outputs a summary of the current jobs.

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math - Perform mathematics calculations

Synopsis

math [-sN] EXPRESSION

Description

math is used to perform mathematical calculations. It is a very thin wrapper for the bc program, which makes it possible to specify an expression from the command line without using non-standard extensions or a pipeline.

For a description of the syntax supported by math, see the manual for the bc program. Keep in mind that parameter expansion takes place on any expressions before they are evaluated. This can be very useful in order to perform calculations involving shell variables or the output of command substitutions, but it also means that parenthesis have to be escaped.

The following options are available:

  • -sN Sets the scale of the result. N must be an integer and defaults to zero. This simply sets bc's scale variable to the provided value. Note that you cannot put a space between -s and N.

Return Values

If invalid options or no expression is provided the return status is two. If the expression is invalid the return status is three. If bc returns a result of 0 (literally, not 0.0 or similar variants) the return status is one otherwise it's zero.

Examples

math 1+1 outputs 2.

math $status-128 outputs the numerical exit status of the last command minus 128.

math 10 / 6 outputs 1.

math -s0 10.0 / 6.0 outputs 1.

math -s3 10 / 6 outputs 1.666.

Cautions

Note that the modulo operator (x % y) is not well defined for floating point arithmetic. The bc command produces a nonsensical result rather than emit an error and fail in that case. It doesn't matter if the arguments are integers; e.g., 10 % 4. You'll still get an incorrect result. Do not use the -sN flag with N greater than zero if you want sensible answers when using the modulo operator.

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nextd - move forward through directory history

Synopsis

nextd [ -l | --list ] [POS]

Description

nextd moves forwards POS positions in the history of visited directories; if the end of the history has been hit, a warning is printed.

If the -l or --list flag is specified, the current directory history is also displayed.

Note that the cd command limits directory history to the 25 most recently visited directories. The history is stored in the $dirprev and $dirnext variables which this command manipulates.

Example

cd /usr/src
# Working directory is now /usr/src

cd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell

prevd
# Working directory is now /usr/src

nextd
# Working directory is now /usr/src/fish-shell

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not - negate the exit status of a job

Synopsis

not COMMAND [OPTIONS...]

Description

not negates the exit status of another command. If the exit status is zero, not returns 1. Otherwise, not returns 0.

Example

The following code reports an error and exits if no file named spoon can be found.

if not test -f spoon
    echo There is no spoon
    exit 1
end

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open - open file in its default application

Synopsis

open FILES...

Description

open opens a file in its default application, using the appropriate tool for the operating system. On GNU/Linux, this requires the common but optional xdg-open utility, from the xdg-utils package.

Example

open *.txt opens all the text files in the current directory using your system's default text editor.

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or - conditionally execute a command

Synopsis

COMMAND1; or COMMAND2

Description

or is used to execute a command if the current exit status (as set by the previous command) is not 0.

or statements may be used as part of the condition in an and or while block. See the documentation for if and while for examples.

or does not change the current exit status. The exit status of the last foreground command to exit can always be accessed using the $status variable.

Example

The following code runs the make command to build a program. If the build succeeds, the program is installed. If either step fails, make clean is run, which removes the files created by the build process.

make; and make install; or make clean

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popd - move through directory stack

Synopsis

popd

Description

popd removes the top directory from the directory stack and changes the working directory to the new top directory. Use pushd to add directories to the stack.

Example

pushd /usr/src
# Working directory is now /usr/src
# Directory stack contains /usr/src

pushd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell
# Directory stack contains /usr/src /usr/src/fish-shell

popd
# Working directory is now /usr/src
# Directory stack contains /usr/src

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prevd - move backward through directory history

Synopsis

prevd [ -l | --list ] [POS]

Description

prevd moves backwards POS positions in the history of visited directories; if the beginning of the history has been hit, a warning is printed.

If the -l or --list flag is specified, the current history is also displayed.

Note that the cd command limits directory history to the 25 most recently visited directories. The history is stored in the $dirprev and $dirnext variables which this command manipulates.

Example

cd /usr/src
# Working directory is now /usr/src

cd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell

prevd
# Working directory is now /usr/src

nextd
# Working directory is now /usr/src/fish-shell

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printf - display text according to a format string

Synopsis

printf format [argument...]

Description

printf formats the string FORMAT with ARGUMENT, and displays the result.

The string FORMAT should contain format specifiers, each of which are replaced with successive arguments according to the specifier. Specifiers are detailed below, and are taken from the C library function printf(3).

Unlike echo, printf does not append a new line unless it is specified as part of the string.

Valid format specifiers are:

  • %d: Argument will be used as decimal integer (signed or unsigned)
  • %i: Argument will be used as a signed integer
  • %o: An octal unsigned integer
  • %u: An unsigned decimal integer
  • %x or %X: An unsigned hexadecimal integer
  • %f, %g or %G: A floating-point number
  • %e or %E: A floating-point number in scientific (XXXeYY) notation
  • %s: A string
  • %b: As a string, interpreting backslash escapes, except that octal escapes are of the form \0 or \0ooo.

%% signifies a literal "%".

Note that conversion may fail, e.g. "102.234" will not losslessly convert to an integer, causing printf to print an error.

printf also knows a number of backslash escapes:

  • \" double quote
  • \\ backslash
  • \a alert (bell)
  • \b backspace
  • \c produce no further output
  • \e escape
  • \f form feed
  • \n new line
  • \r carriage return
  • \t horizontal tab
  • \v vertical tab
  • \ooo octal number (ooo is 1 to 3 digits)
  • \xhh hexadecimal number (hhh is 1 to 2 digits)
  • \uhhhh 16-bit Unicode character (hhhh is 4 digits)
  • \Uhhhhhhhh 32-bit Unicode character (hhhhhhhh is 8 digits)

The format argument is re-used as many times as necessary to convert all of the given arguments. If a format specifier is not appropriate for the given argument, an error is printed. For example, `printf 'd' "102.234"` produces an error, as "102.234" cannot be formatted as an integer.

This file has been imported from the printf in GNU Coreutils version 6.9. If you would like to use a newer version of printf, for example the one shipped with your OS, try command printf.

Example

printf '%s\t%s\n' flounder fish

Will print "flounder fish" (separated with a tab character), followed by a newline character. This is useful for writing completions, as fish expects completion scripts to output the option followed by the description, separated with a tab character.

printf '%s:%d' "Number of bananas in my pocket" 42

Will print "Number of bananas in my pocket: 42", without a newline.

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prompt_pwd - Print pwd suitable for prompt

Synopsis

prompt_pwd

Description

prompt_pwd is a function to print the current working directory in a way suitable for prompts. It will replace the home directory with "~" and shorten every path component but the last to a default of one character.

To change the number of characters per path component, set $fish_prompt_pwd_dir_length to the number of characters. Setting it to 0 or an invalid value will disable shortening entirely.

Examples

> cd ~/
> echo $PWD
/home/alfa

> prompt_pwd
~

> cd /tmp/banana/sausage/with/mustard
> prompt_pwd
/t/b/s/w/mustard

> set -g fish_prompt_pwd_dir_length 3
> prompt_pwd
/tmp/ban/sau/wit/mustard

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psub - perform process substitution

Synopsis

COMMAND1 ( COMMAND2 | psub [-f] [-s SUFFIX])

Description

Posix shells feature a syntax that is a mix between command substitution and piping, called process substitution. It is used to send the output of a command into the calling command, much like command substitution, but with the difference that the output is not sent through commandline arguments but through a named pipe, with the filename of the named pipe sent as an argument to the calling program. psub combined with a regular command substitution provides the same functionality.

If the -f or --file switch is given to psub, psub will use a regular file instead of a named pipe to communicate with the calling process. This will cause psub to be significantly slower when large amounts of data are involved, but has the advantage that the reading process can seek in the stream.

If the -s or ---suffix switch is given, psub will append SUFFIX to the filename.

Example

diff (sort a.txt | psub) (sort b.txt | psub)
# shows the difference between the sorted versions of files `a.txt` and `b.txt`.

source-highlight -f esc (cpp main.c | psub -s .c)
# highlights `main.c` after preprocessing as a C source.

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pushd - push directory to directory stack

Synopsis

pushd [DIRECTORY]

Description

The pushd function adds DIRECTORY to the top of the directory stack and makes it the current working directory. popd will pop it off and return to the original directory.

Without arguments, it exchanges the top two directories in the stack.

pushd +NUMBER rotates the stack counter-clockwise i.e. from bottom to top

pushd -NUMBER rotates clockwise i.e. top to bottom.

See also dirs and dirs -c.

Example

pushd /usr/src
# Working directory is now /usr/src
# Directory stack contains /usr/src

pushd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell
# Directory stack contains /usr/src /usr/src/fish-shell

pushd /tmp/
# Working directory is now /tmp
# Directory stack contains /tmp /usr/src /usr/src/fish-shell

pushd +1
# Working directory is now /usr/src
# Directory stack contains /usr/src /usr/src/fish-shell /tmp

popd
# Working directory is now /usr/src/fish-shell
# Directory stack contains /usr/src/fish-shell /tmp

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pwd - output the current working directory

Synopsis

pwd

Description

pwd outputs (prints) the current working directory.

Note that fish always resolves symbolic links in the current directory path.

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random - generate random number

Synopsis

random [SEED]

Description

random outputs a psuedo-random number from 0 to 32767, inclusive. Even ignoring the very narrow range of values you should not assume this produces truly random values within that range. Do not use the value for any cryptographic purposes, and take care to handle collisions: the same random number appearing more than once in a given fish instance.

If a SEED value is provided, it is used to seed the random number generator, and no output will be produced. This can be useful for debugging purposes, where it can be desirable to get the same random number sequence multiple times. If the random number generator is called without first seeding it, the current time will be used as the seed.

Example

The following code will count down from a random number to 1:

for i in (seq (random) -1 1)
    echo $i
    sleep
end

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read - read line of input into variables

Synopsis

read [OPTIONS] [VARIABLES...]

Description

read reads one line from standard input and stores the result in one or more shell variables.

The following options are available:

  • -c CMD or --command=CMD sets the initial string in the interactive mode command buffer to CMD.
  • -g or --global makes the variables global.
  • -l or --local makes the variables local.
  • -m NAME or --mode-name=NAME specifies that the name NAME should be used to save/load the history file. If NAME is fish, the regular fish history will be available.
  • -n NCHARS or --nchars=NCHARS causes read to return after reading NCHARS characters rather than waiting for a complete line of input.
  • -p PROMPT_CMD or --prompt=PROMPT_CMD uses the output of the shell command PROMPT_CMD as the prompt for the interactive mode. The default prompt command is set_color green; echo read; set_color normal; echo "> ".
  • -R RIGHT_PROMPT_CMD or --right-prompt=RIGHT_PROMPT_CMD uses the output of the shell command RIGHT_PROMPT_CMD as the right prompt for the interactive mode. There is no default right prompt command.
  • -s or --shell enables syntax highlighting, tab completions and command termination suitable for entering shellscript code in the interactive mode.
  • -u or --unexport prevents the variables from being exported to child processes (default behaviour).
  • -U or --universal causes the specified shell variable to be made universal.
  • -x or --export exports the variables to child processes.
  • -a or --array stores the result as an array.
  • -z or --null reads up to NUL instead of newline. Disables interactive mode.

read reads a single line of input from stdin, breaks it into tokens based on the IFS shell variable, and then assigns one token to each variable specified in VARIABLES. If there are more tokens than variables, the complete remainder is assigned to the last variable. As a special case, if IFS is set to the empty string, each character of the input is considered a separate token.

If -a or --array is provided, only one variable name is allowed and the tokens are stored as an array in this variable.

See the documentation for set for more details on the scoping rules for variables.

Example

The following code stores the value 'hello' in the shell variable $foo.

echo hello|read foo

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realpath - Convert a path to an absolute path without symlinks

Synopsis

realpath path

Description

This is implemented as a function and a builtin. The function will attempt to use an external realpath command if one can be found. Otherwise it falls back to the builtin. The builtin does not support any options. It's meant to be used only by scripts which need to be portable. The builtin implementation behaves like GNU realpath when invoked without any options (which is the most common use case). In general scripts should not invoke the builtin directly. They should just use realpath.

If the path is invalid no translated path will be written to stdout and an error will be reported.

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return - stop the current inner function

Synopsis

function NAME; [COMMANDS...;] return [STATUS]; [COMMANDS...;] end

Description

return halts a currently running function. The exit status is set to STATUS if it is given.

It is usually added inside of a conditional block such as an if statement or a switch statement to conditionally stop the executing function and return to the caller, but it can also be used to specify the exit status of a function.

Example

The following code is an implementation of the false command as a fish function

function false
    return 1
end

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set - display and change shell variables.

Synopsis

set [SCOPE_OPTIONS]
set [OPTIONS] VARIABLE_NAME VALUES...
set [OPTIONS] VARIABLE_NAME[INDICES]... VALUES...
set ( -q | --query ) [SCOPE_OPTIONS] VARIABLE_NAMES...
set ( -e | --erase ) [SCOPE_OPTIONS] VARIABLE_NAME
set ( -e | --erase ) [SCOPE_OPTIONS] VARIABLE_NAME[INDICES]...

Description

set manipulates shell variables.

If set is called with no arguments, the names and values of all shell variables are printed. If some of the scope or export flags have been given, only the variables matching the specified scope are printed.

With both variable names and values provided, set assigns the variable VARIABLE_NAME the values VALUES....

The following options control variable scope:

  • -l or --local forces the specified shell variable to be given a scope that is local to the current block, even if a variable with the given name exists and is non-local
  • -g or --global causes the specified shell variable to be given a global scope. Non-global variables disappear when the block they belong to ends
  • -U or --universal causes the specified shell variable to be given a universal scope. If this option is supplied, the variable will be shared between all the current users fish instances on the current computer, and will be preserved across restarts of the shell.
  • -x or --export causes the specified shell variable to be exported to child processes (making it an "environment variable")
  • -u or --unexport causes the specified shell variable to NOT be exported to child processes

The following options are available:

  • -e or --erase causes the specified shell variable to be erased
  • -q or --query test if the specified variable names are defined. Does not output anything, but the builtins exit status is the number of variables specified that were not defined.
  • -n or --names List only the names of all defined variables, not their value
  • -L or --long do not abbreviate long values when printing set variables

If a variable is set to more than one value, the variable will be an array with the specified elements. If a variable is set to zero elements, it will become an array with zero elements.

If the variable name is one or more array elements, such as PATH[1 3 7], only those array elements specified will be changed. When array indices are specified to set, multiple arguments may be used to specify additional indexes, e.g. set PATH[1] PATH[4] /bin /sbin. If you specify a negative index when expanding or assigning to an array variable, the index will be calculated from the end of the array. For example, the index -1 means the last index of an array.

The scoping rules when creating or updating a variable are:

  1. If a variable is explicitly set to either universal, global or local, that setting will be honored. If a variable of the same name exists in a different scope, that variable will not be changed.
  2. If a variable is not explicitly set to be either universal, global or local, but has been previously defined, the previous variable scope is used.
  3. If a variable is not explicitly set to be either universal, global or local and has never before been defined, the variable will be local to the currently executing function. Note that this is different from using the -l or --local flag. If one of those flags is used, the variable will be local to the most inner currently executing block, while without these the variable will be local to the function. If no function is executing, the variable will be global.

The exporting rules when creating or updating a variable are identical to the scoping rules for variables:

  1. If a variable is explicitly set to either be exported or not exported, that setting will be honored.
  2. If a variable is not explicitly set to be exported or not exported, but has been previously defined, the previous exporting rule for the variable is kept.
  3. If a variable is not explicitly set to be either exported or unexported and has never before been defined, the variable will not be exported.

In query mode, the scope to be examined can be specified.

In erase mode, if variable indices are specified, only the specified slices of the array variable will be erased.

set requires all options to come before any other arguments. For example, set flags -l will have the effect of setting the value of the variable flags to '-l', not making the variable local.

In assignment mode, set exits with a non-zero exit status if variable assignments could not be successfully performed. If the variable assignments were performed, the exit status is unchanged. This allows simultaneous capture of the output and exit status of a subcommand, e.g. if set output (command). In query mode, the exit status is the number of variables that were not found. In erase mode, set exits with a zero exit status in case of success, with a non-zero exit status if the commandline was invalid, if the variable was write-protected or if the variable did not exist.

Example

set -xg
# Prints all global, exported variables.

set foo hi
# Sets the value of the variable $foo to be 'hi'.

set -e smurf
# Removes the variable $smurf

set PATH[4] ~/bin
# Changes the fourth element of the $PATH array to ~/bin

if set python_path (which python)
    echo "Python is at $python_path"
end
# Outputs the path to Python if `which` returns true.

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set_color - set the terminal color

Synopsis

set_color [OPTIONS] VALUE

Description

set_color is used to control the color and styling of text in the terminal. VALUE corresponds to a reserved color name such as red or a RGB color value given as 3 or 6 hexadecimal digits. The br-, as in 'bright', forms are full-brightness variants of the 8 standard-brightness colors on many terminals. brblack has higher brightness than black - towards gray. A special keyword normal resets text formatting to terminal defaults.

Valid colors include:

  • black, red, green, yellow, blue, magenta, cyan, white
  • brblack, brred, brgreen, bryellow, brblue, brmagenta, brcyan, brwhite

An RGB value with three or six hex digits, such as A0FF33 or f2f can be used. fish will choose the closest supported color. A three digit value is equivalent to specifying each digit twice; e.g., set_color 2BC is the same as set_color 22BBCC. Hexadecimal RGB values can be in lower or uppercase. Depending on the capabilities of your terminal (and the level of support set_color has for it) the actual color may be approximated by a nearby matching reserved color name or set_color may not have an effect on color. A second color may be given as a desired fallback color. e.g. set_color 124212 brblue will instruct set_color to use brblue if a terminal is not capable of the exact shade of grey desired. This is very useful when an 8 or 16 color terminal might otherwise not use a color.

The following options are available:

  • -b, --background COLOR sets the background color.
  • -c, --print-colors prints a list of the 16 named colors.
  • -o, --bold sets bold mode.
  • -u, --underline sets underlined mode.

Using the normal keyword will reset foreground, background, and all formatting back to default.

Notes

  1. Using the normal keyword will reset both background and foreground colors to whatever is the default for the terminal.
  2. Setting the background color only affects subsequently written characters. Fish provides no way to set the background color for the entire terminal window. Configuring the window background color (and other attributes such as its opacity) has to be done using whatever mechanisms the terminal provides.
  3. Some terminals use the --bold escape sequence to switch to a brighter color set rather than increasing the weight of text.
  4. set_color works by printing sequences of characters to stdout. If used in command substitution or a pipe, these characters will also be captured. This may or may not be desirable. Checking the exit code of isatty stdout before using set_color can be useful to decide not to colorize output in a script.

Examples

set_color red; echo "Roses are red"
set_color blue; echo "Violets are blue"
set_color 62A; echo "Eggplants are dark purple"
set_color normal; echo "Normal is nice" ## Resets the background too

Terminal Capability Detection

Fish uses a heuristic to decide if a terminal supports the 256-color palette as opposed to the more limited 16 color palette of older terminals. Support can be forced on by setting fish_term256 to 1. If $TERM contains "256color" (e.g., xterm-256color), 256-color support is enabled. If $TERM contains xterm, 256 color support is enabled (except for MacOS: $TERM_PROGRAM and $TERM_PROGRAM_VERSION are used to detect Terminal.app from MacOS 10.6; support is disabled here it because it is known that it reports xterm and only supports 16 colors.

If terminfo reports 256 color support for a terminal, support will always be enabled. To debug color palette problems, tput colors may be useful to see the number of colors in terminfo for a terminal. Fish launched as fish -d2 will include diagnostic messages that indicate the color support mode in use.

Many terminals support 24-bit (i.e., true-color) color escape sequences. This includes modern xterm, Gnome Terminal, Konsole, and iTerm2. Fish attempts to detect such terminals through various means in config.fish You can explicitly force that support via set fish_term24bit 1.

The set_color command uses the terminfo database to look up how to change terminal colors on whatever terminal is in use. Some systems have old and incomplete terminfo databases, and may lack color information for terminals that support it. Fish will assume that all terminals can use the ANSI X3.64 escape sequences if the terminfo definition indicates a color below 16 is not supported.

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source - evaluate contents of file.

Synopsis

source FILENAME [ARGUMENTS...]

Description

source evaluates the commands of the specified file in the current shell. This is different from starting a new process to perform the commands (i.e. fish < FILENAME) since the commands will be evaluated by the current shell, which means that changes in shell variables will affect the current shell. If additional arguments are specified after the file name, they will be inserted into the $argv variable. The $argv variable will not include the name of the sourced file.

If no file is specified, or if the file name '-' is used, stdin will be read.

The return status of source is the return status of the last job to execute. If something goes wrong while opening or reading the file, source exits with a non-zero status.

. (a single period) is an alias for the source command. The use of . is deprecated in favour of source, and . will be removed in a future version of fish.

Example

source ~/.config/fish/config.fish
# Causes fish to re-read its initialization file.

Caveats

In fish versions prior to 2.3.0 the $argv variable would have a single element (the name of the sourced file) if no arguments are present. Otherwise it would contain arguments without the name of the sourced file. That behavior was very confusing and unlike other shells such as bash and zsh.

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status - query fish runtime information

Synopsis

status [OPTION]

Description

With no arguments, status displays a summary of the current login and job control status of the shell.

The following options are available:

  • -c or --is-command-substitution returns 0 if fish is currently executing a command substitution.
  • -b or --is-block returns 0 if fish is currently executing a block of code.
  • -i or --is-interactive returns 0 if fish is interactive - that is, connected to a keyboard.
  • -l or --is-login returns 0 if fish is a login shell - that is, if fish should perform login tasks such as setting up the PATH.
  • --is-full-job-control returns 0 if full job control is enabled.
  • --is-interactive-job-control returns 0 if interactive job control is enabled.
  • --is-no-job-control returns 0 if no job control is enabled.
  • -f or --current-filename prints the filename of the currently running script.
  • -n or --current-line-number prints the line number of the currently running script.
  • -j CONTROLTYPE or --job-control=CONTROLTYPE sets the job control type, which can be none, full, or interactive.
  • -t or --print-stack-trace prints a stack trace of all function calls on the call stack.

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string - manipulate strings

Synopsis

string length [(-q | --quiet)] [STRING...]
string sub [(-s | --start) START] [(-l | --length) LENGTH] [(-q | --quiet)]
           [STRING...]
string split [(-m | --max) MAX] [(-r | --right)] [(-q | --quiet)] SEP
             [STRING...]
string join [(-q | --quiet)] SEP [STRING...]
string trim [(-l | --left)] [(-r | --right)] [(-c | --chars CHARS)]
            [(-q | --quiet)] [STRING...]
string escape [(-n | --no-quoted)] [STRING...]
string match [(-a | --all)] [(-i | --ignore-case)] [(-r | --regex)]
             [(-n | --index)] [(-q | --quiet)] [(-v | --invert)] PATTERN [STRING...]
string replace [(-a | --all)] [(-i | --ignore-case)] [(-r | --regex)]
               [(-q | --quiet)] PATTERN REPLACEMENT [STRING...]

Description

string performs operations on strings.

STRING arguments are taken from the command line unless standard input is connected to a pipe or a file, in which case they are read from standard input, one STRING per line. It is an error to supply STRING arguments on the command line and on standard input.

Arguments beginning with - are normally interpreted as switches; -- causes the following arguments not to be treated as switches even if they begin with -. Switches and required arguments are recognized only on the command line.

Most subcommands accept a -q or --quiet switch, which suppresses the usual output but exits with the documented status.

In addition to the exit codes documented below, all the string subcommands exit with a value of 2 to indicate that an error occurred.

The following subcommands are available:

  • length reports the length of each string argument in characters. Exit status: 0 if at least one non-empty STRING was given, or 1 otherwise.
  • sub prints a substring of each string argument. The start of the substring can be specified with -s or --start followed by a 1-based index value. Positive index values are relative to the start of the string and negative index values are relative to the end of the string. The default start value is 1. The length of the substring can be specified with -l or --length. If the length is not specified, the substring continues to the end of each STRING. Exit status: 0 if at least one substring operation was performed, 1 otherwise.
  • split splits each STRING on the separator SEP, which can be an empty string. If -m or --max is specified, at most MAX splits are done on each STRING. If -r or --right is given, splitting is performed right-to-left. This is useful in combination with -m or --max. Exit status: 0 if at least one split was performed, or 1 otherwise.
  • join joins its STRING arguments into a single string separated by SEP, which can be an empty string. Exit status: 0 if at least one join was performed, or 1 otherwise.
  • trim removes leading and trailing whitespace from each STRING. If -l or --left is given, only leading whitespace is removed. If -r or --right is given, only trailing whitespace is trimmed. The -c or --chars switch causes the characters in CHARS to be removed instead of whitespace. Exit status: 0 if at least one character was trimmed, or 1 otherwise.
  • escape escapes each STRING such that it can be passed back to eval to produce the original argument again. By default, all special characters are escaped, and quotes are used to simplify the output when possible. If -n or --no-quoted is given, the simplifying quoted format is not used. Exit status: 0 if at least one string was escaped, or 1 otherwise.
  • match tests each STRING against PATTERN and prints matching substrings. Only the first match for each STRING is reported unless -a or --all is given, in which case all matches are reported. Matching can be made case-insensitive with -i or --ignore-case. If -n or --index is given, each match is reported as a 1-based start position and a length. By default, PATTERN is interpreted as a glob pattern matched against each entire STRING argument. A glob pattern is only considered a valid match if it matches the entire STRING. If -r or --regex is given, PATTERN is interpreted as a Perl-compatible regular expression, which does not have to match the entire STRING. For a regular expression containing capturing groups, multiple items will be reported for each match, one for the entire match and one for each capturing group. If –invert or -v is used the selected lines will be only those which do not match the given glob pattern or regular expression. Exit status: 0 if at least one match was found, or 1 otherwise.
  • replace is similar to match but replaces non-overlapping matching substrings with a replacement string and prints the result. By default, PATTERN is treated as a literal substring to be matched. If -r or --regex is given, PATTERN is interpreted as a Perl-compatible regular expression, and REPLACEMENT can contain C-style escape sequences like \t as well as references to capturing groups by number or name as $n or ${n}. Exit status: 0 if at least one replacement was performed, or 1 otherwise.

Regular Expressions

Both the match and replace subcommand support regular expressions when used with the -r or --regex option. The dialect is that of PCRE2.

In general, special characters are special by default, so a+ matches one or more "a"s, while a\+ matches an "a" and then a "+". (a+) matches one or more "a"s in a capturing group ((?:XXXX) denotes a non-capturing group). For the replacement parameter of replace, $n refers to the n-th group of the match. In the match parameter, \n (e.g. \1) refers back to groups.

Examples

> string length 'hello, world'
12

> set str foo
> string length -q $str; echo $status
0
# Equivalent to test -n $str
> string sub --length 2 abcde
ab

> string sub -s 2 -l 2 abcde
bc

> string sub --start=-2 abcde
de
> string split . example.com
example
com

> string split -r -m1 / /usr/local/bin/fish
/usr/local/bin
fish

> string split '' abc
a
b
c
> seq 3 | string join ...
1...2...3
> string trim ' abc  '
abc

> string trim --right --chars=yz xyzzy zany
x
zan
> echo \x07 | string escape
\cg

Match Glob Examples

> string match '?' a
a

> string match 'a*b' axxb
axxb

> string match -i 'a??B' Axxb
Axxb

> echo 'ok?' | string match '*\?'
>_ ok?

Match Regex Examples

> string match -r 'cat|dog|fish' 'nice dog'
dog

> string match -r -v "c.*[12]" {cat,dog}(seq 1 4)
dog1
dog2
cat3
dog3
cat4
dog4

> string match -r '(\d\d?):(\d\d):(\d\d)' 2:34:56
2:34:56
2
34
56

> string match -r '^(\w{2,4})\g1$' papa mud murmur
papa
pa
murmur
mur

> string match -r -a -n at ratatat
2 2
4 2
6 2

> string match -r -i '0x[0-9a-f]{1,8}' 'int magic = 0xBadC0de;'
0xBadC0de

Replace Literal Examples

> string replace is was 'blue is my favorite'
blue was my favorite

> string replace 3rd last 1st 2nd 3rd
1st
2nd
last

> string replace -a ' ' _ 'spaces to underscores'
spaces_to_underscores

Replace Regex Examples

> string replace -r -a '[^\d.]+' ' ' '0 one two 3.14 four 5x'
0 3.14 5

> string replace -r '(\w+)\s+(\w+)' '$2 $1 $$' 'left right'
right left $

> string replace -r '\s*newline\s*' '\n' 'put a newline here'
put a
here

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suspend - suspend the current shell

Synopsis

suspend [--force]

Description

suspend suspends execution of the current shell by sending it a SIGTSTP signal, returning to the controlling process. It can be resumed later by sending it a SIGCONT. In order to prevent suspending a shell that doesn't have a controlling process, it will not suspend the shell if it is a login shell. This requirement is bypassed if the --force option is given or the shell is not interactive.

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switch - conditionally execute a block of commands

Synopsis

switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end

Description

switch performs one of several blocks of commands, depending on whether a specified value equals one of several wildcarded values. case is used together with the switch statement in order to determine which block should be executed.

Each case command is given one or more parameters. The first case command with a parameter that matches the string specified in the switch command will be evaluated. case parameters may contain wildcards. These need to be escaped or quoted in order to avoid regular wildcard expansion using filenames.

Note that fish does not fall through on case statements. Only the first matching case is executed.

Note that command substitutions in a case statement will be evaluated even if its body is not taken. All substitutions, including command substitutions, must be performed before the value can be compared against the parameter.

Example

If the variable $animal contains the name of an animal, the following code would attempt to classify it:

switch $animal
    case cat
        echo evil
    case wolf dog human moose dolphin whale
        echo mammal
    case duck goose albatross
        echo bird
    case shark trout stingray
        echo fish
    case '*'
        echo I have no idea what a $animal is
end

If the above code was run with $animal set to whale, the output would be mammal.

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test - perform tests on files and text

Synopsis

test [EXPRESSION]
[ [EXPRESSION] ]

Description

Tests the expression given and sets the exit status to 0 if true, and 1 if false. An expression is made up of one or more operators and their arguments.

The first form (test) is preferred. For compatibility with other shells, the second form is available: a matching pair of square brackets ([ [EXPRESSION ] ]).

This test is mostly POSIX-compatible.

Operators for files and directories

  • -b FILE returns true if FILE is a block device.
  • -c FILE returns true if FILE is a character device.
  • -d FILE returns true if FILE is a directory.
  • -e FILE returns true if FILE exists.
  • -f FILE returns true if FILE is a regular file.
  • -g FILE returns true if FILE has the set-group-ID bit set.
  • -G FILE returns true if FILE exists and has the same group ID as the current user.
  • -L FILE returns true if FILE is a symbolic link.
  • -O FILE returns true if FILE exists and is owned by the current user.
  • -p FILE returns true if FILE is a named pipe.
  • -r FILE returns true if FILE is marked as readable.
  • -s FILE returns true if the size of FILE is greater than zero.
  • -S FILE returns true if FILE is a socket.
  • -t FD returns true if the file descriptor FD is a terminal (TTY).
  • -u FILE returns true if FILE has the set-user-ID bit set.
  • -w FILE returns true if FILE is marked as writable; note that this does not check if the filesystem is read-only.
  • -x FILE returns true if FILE is marked as executable.

Operators for text strings

  • STRING1 = STRING2 returns true if the strings STRING1 and STRING2 are identical.
  • STRING1 != STRING2 returns true if the strings STRING1 and STRING2 are not identical.
  • -n STRING returns true if the length of STRING is non-zero.
  • -z STRING returns true if the length of STRING is zero.

Operators to compare and examine numbers

  • NUM1 -eq NUM2 returns true if NUM1 and NUM2 are numerically equal.
  • NUM1 -ne NUM2 returns true if NUM1 and NUM2 are not numerically equal.
  • NUM1 -gt NUM2 returns true if NUM1 is greater than NUM2.
  • NUM1 -ge NUM2 returns true if NUM1 is greater than or equal to NUM2.
  • NUM1 -lt NUM2 returns true if NUM1 is less than NUM2.
  • NUM1 -le NUM2 returns true if NUM1 is less than or equal to NUM2.

Note that only integers are supported. For more complex mathematical operations, including fractions, the env program may be useful. Consult the documentation for your operating system.

Operators to combine expressions

  • COND1 -a COND2 returns true if both COND1 and COND2 are true.
  • COND1 -o COND2 returns true if either COND1 or COND2 are true.

Expressions can be inverted using the ! operator:

  • ! EXPRESSION returns true if EXPRESSION is false, and false if EXPRESSION is true.

Expressions can be grouped using parentheses.

  • ( EXPRESSION ) returns the value of EXPRESSION.

    Note that parentheses will usually require escaping with \( to avoid being interpreted as a command substitution.

Examples

If the /tmp directory exists, copy the /etc/motd file to it:

if test -d /tmp
    cp /etc/motd /tmp/motd
end

If the variable MANPATH is defined and not empty, print the contents. (If MANPATH is not defined, then it will expand to zero arguments, unless quoted.)

if test -n "$MANPATH"
    echo $MANPATH
end

Parentheses and the -o and -a operators can be combined to produce more complicated expressions. In this example, success is printed if there is a /foo or /bar file as well as a /baz or /bat file.

if test \( -f /foo -o -f /bar \) -a \( -f /baz -o -f /bat \)
    echo Success.
end.

Numerical comparisons will simply fail if one of the operands is not a number:

if test 42 -eq "The answer to life, the universe and everything"
    echo So long and thanks for all the fish ## will not be executed
end

A common comparison is with $status:

if test $status -eq 0
    echo "Previous command succeeded"
end

Standards

test implements a subset of the IEEE Std 1003.1-2008 (POSIX.1) standard. The following exceptions apply:

  • The < and > operators for comparing strings are not implemented.
  • Because this test is a shell builtin and not a standalone utility, using the -c flag on a special file descriptors like standard input and output may not return the same result when invoked from within a pipe as one would expect when invoking the test utility in another shell.

    In cases such as this, one can use command test to explicitly use the system's standalone test rather than this builtin test.

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trap - perform an action when the shell receives a signal

Synopsis

trap [OPTIONS] [[ARG] SIGSPEC ... ]

Description

trap is a wrapper around the fish event delivery framework. It exists for backwards compatibility with POSIX shells. For other uses, it is recommended to define an event handler.

The following parameters are available:

  • ARG is the command to be executed on signal delivery.
  • SIGSPEC is the name of the signal to trap.
  • -l or --list-signals prints a list of signal names.
  • -p or --print prints all defined signal handlers.

If ARG and SIGSPEC are both specified, ARG is the command to be executed when the signal specified by SIGSPEC is delivered.

If ARG is absent (and there is a single SIGSPEC) or -, each specified signal is reset to its original disposition (the value it had upon entrance to the shell). If ARG is the null string the signal specified by each SIGSPEC is ignored by the shell and by the commands it invokes.

If ARG is not present and -p has been supplied, then the trap commands associated with each SIGSPEC are displayed. If no arguments are supplied or if only -p is given, trap prints the list of commands associated with each signal.

Signal names are case insensitive and the SIG prefix is optional.

The return status is 1 if any SIGSPEC is invalid; otherwise trap returns 0.

Example

trap "status --print-stack-trace" SIGUSR1
# Prints a stack trace each time the SIGUSR1 signal is sent to the shell.

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true - return a successful result

Synopsis

true

Description

true sets the exit status to 0.

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type - indicate how a command would be interpreted

Synopsis

type [OPTIONS] NAME [NAME ...]

Description

With no options, type indicates how each NAME would be interpreted if used as a command name.

The following options are available:

  • -a or --all prints all of possible definitions of the specified names.
  • -f or --no-functions suppresses function and builtin lookup.
  • -t or --type prints function, builtin, or file if NAME is a shell function, builtin, or disk file, respectively.
  • -p or --path returns the name of the disk file that would be executed, or nothing if type -t name would not return file.
  • -P or --force-path returns the name of the disk file that would be executed, or nothing if no file with the specified name could be found in the $PATH.
  • -q or --quiet suppresses all output; this is useful when testing the exit status.

Example

> type fg
fg is a builtin

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ulimit - set or get resource usage limits

Synopsis

ulimit [OPTIONS] [LIMIT]

Description

ulimit builtin sets or outputs the resource usage limits of the shell and any processes spawned by it. If a new limit value is omitted, the current value of the limit of the resource is printed; otherwise, the specified limit is set to the new value.

Use one of the following switches to specify which resource limit to set or report:

  • -c or --core-size: the maximum size of core files created. By setting this limit to zero, core dumps can be disabled.
  • -d or --data-size: the maximum size of a process' data segment.
  • -f or --file-size: the maximum size of files created by the shell.
  • -l or --lock-size: the maximum size that may be locked into memory.
  • -m or --resident-set-size: the maximum resident set size.
  • -n or --file-descriptor-count: the maximum number of open file descriptors (most systems do not allow this value to be set).
  • -s or --stack-size: the maximum stack size.
  • -t or --cpu-time: the maximum amount of CPU time in seconds.
  • -u or --process-count: the maximum number of processes available to a single user.
  • -v or --virtual-memory-size The maximum amount of virtual memory available to the shell.

Note that not all these limits are available in all operating systems.

The value of limit can be a number in the unit specified for the resource or one of the special values hard, soft, or unlimited, which stand for the current hard limit, the current soft limit, and no limit, respectively.

If limit is given, it is the new value of the specified resource. If no option is given, then -f is assumed. Values are in kilobytes, except for -t, which is in seconds and -n and -u, which are unscaled values. The return status is 0 unless an invalid option or argument is supplied, or an error occurs while setting a new limit.

ulimit also accepts the following switches that determine what type of limit to set:

  • -H or --hard sets hard resource limit
  • -S or --soft sets soft resource limit

A hard limit can only be decreased. Once it is set it cannot be increased; a soft limit may be increased up to the value of the hard limit. If neither -H nor -S is specified, both the soft and hard limits are updated when assigning a new limit value, and the soft limit is used when reporting the current value.

The following additional options are also understood by ulimit:

  • -a or --all prints all current limits

The fish implementation of ulimit should behave identically to the implementation in bash, except for these differences:

  • Fish ulimit supports GNU-style long options for all switches
  • Fish ulimit does not support the -p option for getting the pipe size. The bash implementation consists of a compile-time check that empirically guesses this number by writing to a pipe and waiting for SIGPIPE. Fish does not do this because it this method of determining pipe size is unreliable. Depending on bash version, there may also be further additional limits to set in bash that do not exist in fish.
  • Fish ulimit does not support getting or setting multiple limits in one command, except reporting all values using the -a switch

Example

ulimit -Hs 64 sets the hard stack size limit to 64 kB.

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umask - set or get the file creation mode mask

Synopsis

umask [OPTIONS] [MASK]

Description

umask displays and manipulates the "umask", or file creation mode mask, which is used to restrict the default access to files.

The umask may be expressed either as an octal number, which represents the rights that will be removed by default, or symbolically, which represents the only rights that will be granted by default.

Access rights are explained in the manual page for the chmod(1) program.

With no parameters, the current file creation mode mask is printed as an octal number.

  • -h or --help prints this message.
  • -S or --symbolic prints the umask in symbolic form instead of octal form.
  • -p or --as-command outputs the umask in a form that may be reused as input

If a numeric mask is specified as a parameter, the current shell's umask will be set to that value, and the rights specified by that mask will be removed from new files and directories by default.

If a symbolic mask is specified, the desired permission bits, and not the inverse, should be specified. A symbolic mask is a comma separated list of rights. Each right consists of three parts:

  • The first part specifies to whom this set of right applies, and can be one of u, g, o or a, where u specifies the user who owns the file, g specifies the group owner of the file, o specific other users rights and a specifies all three should be changed.
  • The second part of a right specifies the mode, and can be one of =, + or -, where = specifies that the rights should be set to the new value, + specifies that the specified right should be added to those previously specified and - specifies that the specified rights should be removed from those previously specified.
  • The third part of a right specifies what rights should be changed and can be any combination of r, w and x, representing read, write and execute rights.

If the first and second parts are skipped, they are assumed to be a and =, respectively. As an example, r,u+w means all users should have read access and the file owner should also have write access.

Note that symbolic masks currently do not work as intended.

Example

umask 177 or umask u=rw sets the file creation mask to read and write for the owner and no permissions at all for any other users.

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vared - interactively edit the value of an environment variable

Synopsis

vared VARIABLE_NAME

Description

vared is used to interactively edit the value of an environment variable. Array variables as a whole can not be edited using vared, but individual array elements can.

Example

vared PATH[3] edits the third element of the PATH array

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while - perform a command multiple times

Synopsis

while CONDITION; COMMANDS...; end

Description

while repeatedly executes CONDITION, and if the exit status is 0, then executes COMMANDS.

If the exit status of CONDITION is non-zero on the first iteration, COMMANDS will not be executed at all.

You can use and or or for complex conditions. Even more complex control can be achieved with while true containing a break.

Example

while test -f foo.txt; or test -f bar.txt ; echo file exists; sleep 10; end
# outputs 'file exists' at 10 second intervals as long as the file foo.txt or bar.txt exists.

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