Fish ships with a large number of builtin commands, shellscript functions and external commands.
These are all described below.
alias NAME DEFINITION alias NAME=DEFINITION
Alias is a shellscript wrapper around the function builtin. It exists for backwards compatibility with Posix shells. For other uses, it is recommended to define a function.
Alias does not keep track of which functions have been defined using alias, nor does it allow erasing of aliases.
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COMMAND1; and COMMAND2
The and builtin is used to execute a command if the current exit status (as set by the last previous command) is 0.
The and command 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.
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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begin; [COMMANDS...;] end
The begin builtin is used to create a new block of code. The block is unconditionally executed. begin; ...; end is equivalent to if true; ...; end. The begin command is used to group any number of commands into a block. The reason for doing so is usually either to introduce a new variable scope, to redirect the input or output of a set of commands as a group, or to specify precedence when using the conditional commands like and.
The begin command does not change the current exit status.
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 # This will not output anything, since the PIRATE variable went out # of scope at the end of the block echo $PIRATE
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 [PID...]
Sends the specified jobs to the background. 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 group ids are put in the background.
The PID of the desired process is usually found by using process expansion.
bg %0 will put the job with job id 0 in the background.
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bind [OPTIONS] SEQUENCE COMMAND
The bind builtin causes fish to add a key binding from the specified sequence.
SEQUENCE is the character sequence to bind to. Usually, one would use fish escape sequences to express them. 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. Control character can be written in much the same way using the \c escape, for example Control-x can be written as \cx. Note that Alt-based key bindings are case sensitive and Control base key bindings are not. This is not a design choice in fish, it is simply how terminals work.
If SEQUENCE is the empty string, i.e. an empty set of quotes, this is interpreted as the default keybinding. 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 keybining. 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 e.g. 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 man 5 terminfo 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.
-a or --all If --key-names is specified, show all key names, not only the ones that actually are defined for the current terminal. If erase mode is specified, this switch will cause all current bindings to be erased.-e or --erase Erase mode. All non-switch arguments are interpreted as character sequences and any commands associated with those sequences are erased.-h or --help Display help and exit-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-f or --function-names Display a list of available input functionsbind \cd 'exit' causes fish to exit on Control-d
bind -k ppage history-search-backward Causes fish to perform a history search when the page up key is pressed
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block [OPTIONS...]
-l or --local Release the block at the end of the currently innermost block scope-g or --global Never automatically release the lock-e or --erase Release global blockblock -g #Do something that should not be interrupted block -e
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LOOP_CONSTRUCT; [COMMANDS...] break; [COMMANDS...] end
The break builtin is used to halt 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.
The following code searches all .c files for smurfs, 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
The breakpoint builtin is used to halt a running script and launch an interactive debug prompt.
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builtin BUILTINNAME [OPTIONS...]
-n or --names List the names of all defined builtinsPrefixing a command with the word 'builtin' forces fish to ignore any functions with the same name.
builtin jobs
causes fish to execute the jobs builtin, even if a function named jobs exists.
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switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end
The switch statement is used to perform one of several blocks of commands depending on whether a specified value equals one of several wildcarded values. The case statement is used together with the switch statement in order to determine which block should be performed.
Each case command is given one or more parameter. 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. Though the syntax may look a bit like C switch statements, it behaves more like the case statements of traditional shells.
Also note that command substitutions in a case statement will be evaluated even if it's body is not taken. This may seem counterintuitive at first, but it is unavoidable, since it would be impossible to know if a case command will evaluate to true before all forms of parameter expansion have been performed for the case command.
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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cd [DIRECTORY]
directory. If DIRECTORY is supplied it will become the new directory. If DIRECTORY is a relative path, the paths found in the CDPATH environment variable array will be tried as prefixes for the specified path. If CDPATH is not set, it is assumed to be '.'. If DIRECTORY is not specified, $HOME will be the new directory.
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command COMMANDNAME [OPTIONS...]
prefixing a command with the word 'command' forces fish to ignore any functions or builtins with the same name.
command ls
causes fish to execute the ls program, even if there exists a 'ls' function.
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commandline [OPTIONS] [CMD]
CMD is the new value of the commandline. If unspecified, the current value of the commandline is written to standard output. All output from the commandline builtin is escaped, i.e. quotes are removed, backslash escapes are expanded, etc..The following switches change what the commandline builtin does
-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 can not 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 switches change the way commandline updates the commandline 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 switches 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 switch changes 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 lineIf 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 commandline.
commandline -j $history[3]
replaces the job under the cursor with the third item from the commandline history.
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complete (-c|--command|-p|--path) COMMAND [(-s|--short-option) SHORT_OPTION] [(-l|--long-option|-o|--old-option) LONG_OPTION [(-a||--arguments) OPTION_ARGUMENTS] [(-d|--description) DESCRIPTION]
For an introduction to how to specify completions, see the section Writing your own completions of the fish manual.
COMMAND is the name of the command for which to add a completionSHORT_OPTION is a one character option for the commandLONG_OPTION is a multi character option for the commandOPTION_ARGUMENTS is parameter containing a space-separated list of possible option-arguments, which may contain subshellsDESCRIPTION is a description of what the option and/or option arguments do-C STRING or --do-complete=STRING makes complete try to find all possible completions for the specified string-e or --erase implies that the specified completion should be deleted-f or --no-files specifies that the option specified by this completion may not be followed by a filename-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.-o or --old-option implies that the command uses old long style options with only one dash-p or --path implies that the string COMMAND is the full path of the command-r or --require-parameter specifies that the option specified by this completion always must have an option argument, i.e. may not be followed by another option-u or --unauthoritative implies that there may be more options than the ones specified, and that fish should not assume that options not listed are spelling errors-A or --authoritative implies that there may be no more options than the ones specified, and that fish should assume that options not listed are spelling errors-x or --exclusive implies both -r and -fCommand 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:
The options for specifying command name, command path, or command switches may all be used multiple times to specify multiple commands which have the same completion or multiple switches accepted by a command.
When erasing completions, it is possible to either erase all completions for a specific command by specifying complete -e -c COMMAND, or by specifying a specific completion option to delete by specifying either a long, short or old style option.
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" -l nodeps -d "Don't check dependencies"
where __fish_contains_opt is a function that checks the commandline buffer for the presence of a specified set of options.
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contains [OPTIONS] KEY [VALUES...]
-h or --help display this messageTest if the set VALUES contains the string KEY. Return status is 0 if yes, 1 otherwise
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 if they are not, they are added.
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LOOP_CONSTRUCT; [COMMANDS...;] continue; [COMMANDS...;] end
The continue builtin is used to skip the current lap of the innermost 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.
The following code removes all tmp files without smurfs.
for i in *.tmp
if grep smurf $i
continue
end
rm $i
end
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count $VARIABLE
The count builtin 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, but this is not the only potential usage for the count command.
The count command does not accept any options, not even '-h'. This way the user does not have to worry about an array containing elements such as dashes. fish performs a special check when invoking the count command, and if the user uses a help option, this help page is displayed, but if a help option is contained inside of a variable or is the result of expansion, it will simply be counted like any other argument.
Count exits with a non-zero exit status if no arguments where passed to it, with zero otherwise.
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
dirh prints the current directory history. The current position in the history is highlighted using $fish_color_history_current.
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dirs
dirs prints the current directory stack.
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if CONDITION; COMMANDS_TRUE...; [else; COMMANDS_FALSE...;] end
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. Hint: use begin; ...; end for complex conditions.
The command if test -f foo.txt; echo foo.txt exists; else; echo foo.txt does not exist; end will print foo.txt exists if the file foo.txt exists and is a regular file, otherwise it will print foo.txt does not exist.
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emit EVENT_NAME
The emit builtin fires a generic fish event. Such events can be caught by special functions called event handlers.
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!!!
endemit test_event
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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
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 [COMMANDS...]
The eval function causes fish to evaluate 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.
set cmd ls eval $cmd
will call the ls command.
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exec COMMAND [OPTIONS...]
The exec builtin is used to replace the currently running shells process image with a new command. On successful completion, exec never returns. exec can not be used inside a pipeline.
exec emacs starts up the emacs text editor. When emacs exits, the session will terminate.
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exit [STATUS]
The exit builtin 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 . builtin) the rest of the file will be skipped, but the shell itself will not exit.
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fg [PID]
Sends the specified job to the foreground. 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.
fg %0 will put the job with job id 0 in the foreground.
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fish [-h] [-v] [-c command] [FILE [ARGUMENTS...]]
A commandline shell written mainly with interactive use in mind. The full manual is available in html by using the help command from inside fish.
-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.-h or --help display help and exit-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 exitThe 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_indent [options]
fish_indent is used to indent or otherwise prettify a piece of fish code. fish_indent reads commands from standard input and outputs them to standard output.
fish_indent understands the following options:
-h or --help displays this help message and then exits-i or --no-indent do not indent commands-v or --version displays the current fish version and then exitsBack to index.
This command is used internally by fish to display a list of completions. It should not be used by other commands, as it's interface is liable to change in the future.
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function fish_prompt
...
endBy 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.
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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fishd [(-h|--help|-v|--version)]
The fishd daemon is used to load, save and distribute universal variable information. fish automatically connects to fishd via a socket on startup. If no instance of fishd is running, fish spawns a new fishd instance. fishd will create a socket in /tmp, and wait for incoming connections from universal variable clients, such as fish, When no clients are connected, fishd will automatically shut down.
-h or --help displays this help message and then exits-v or --version displays the current fish version and then exits~/.config/fish/fishd.HOSTNAME permanent storage location for universal variable data. The data is stored as a set of set and set_export commands such as would be parsed by fishd. The file must always be stored in ASCII format. If an instance of fishd is running (which is generally the case), manual modifications to ~/.fishd.HOSTNAME will be lost. Do NOT edit this file manually!
/tmp/fishd.socket.USERNAME the socket which fishd uses to communicate with all clients.
/tmp/fishd.log.USERNAME the fishd log file
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for VARNAME in [VALUES...]; COMMANDS...; end
for is a loop construct. It will perform the commands specified by COMMANDS multiple times. Each time the environment variable specified by VARNAME is assigned a new value from VALUES. If VALUES is empty, COMMANDS will not be executed at all.
The command
for i in foo bar baz; echo $i; end
would output:
foo bar baz
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funced NAME
Use the funced command to interactively edit the definition of a function. If there is no function with the name specified, a skeleton function is inserted, if a function exist, the definion will be shown on the command line.
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funcsave FUNCTION_NAME
funcsave is used to save the current definition of a function to a file which will be autoloaded 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.
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function [OPTIONS] NAME; BODY; end
-d DESCRIPTION or --description=DESCRIPTION is a description of what the function does, suitable as a completion description-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.-j PID or --on-job-exit PID tells fish to run this function when the job with group id PID exits. Instead of PID, 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)-v or --on-variable VARIABLE_NAME tells fish to run this function when the variable VARIABLE_NAME changes valueThis builtin command is used to create a new function. A function is a list of commands that will be executed when the name of the function is entered. The function
function hi echo hello end
will write hello whenever the user enters hi.
If the user enters any additional arguments after the function, they are inserted into the environment variable array argv.
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 <a href='#emit">emit builtin. Fish generates the following named events:
fish_prompt, which is emitted whenever a new fish prompt is about to be displayedfish_command_not_found, which is emitted whenever a command lookup failedfunction 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" mkdir $argv if test $status = 0 switch $argv[(count $argv)] case '-*'
case '*' cd $argv[(count $argv)] return end end end
will run the mkdir command, and if it is successful, change the current working directory to the one just created.
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functions [-e] FUNCTIONS...
This builtin command is used to print or erase functions.
-a or --all list 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 change the description of this function-e or --erase causes the specified functions to be erased.-h or --help display a help message and exit-n or --names list only the names of all defined functions, not their definition-q or --query test if the specified functions exist. Does not output anything, but the builtins exit status is the number of functions specified that were not defined.The default behavior of functions when called with no arguments, is to print the names and definitions of all defined functions. If any non-switch parameters are given, only the definition of the specified functions are printed.
Automatically loaded functions can not be removed using functions -e. Either remove the definition file or change the $fish_function_path variable to remove autoloaded functions.
Function copies, created with -c, will not have any event/signal/on-exit notifications that the original may have had.
The exit status of the functions builtin is the number functions specified in the argument list that do not exist.
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help [SECTION]
The help command is used to display a section of the fish help documentation.
If the BROWSER environment variable is set, it will be used to display the documentation, otherwise fish will search for a suitable browser.
Note also that most builtin commands display their help in the terminal when given the --help option.
help fg shows the documentation for the fg builtin.
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if CONDITION; COMMANDS_TRUE...; [else; COMMANDS_FALSE...;] end
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.
In order to use the exit status of multiple commands as the condition of an if block, use begin; ...; end and the short circuit commands and and or.
The exit status of the last foreground command to exit can always be accessed using the $status variable.
if test -f foo.txt echo foo.txt exists else echo foo.txt does not exist end
will print foo.txt exists if the file foo.txt exists and is a regular file, otherwise it will print foo.txt does not exist.
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isatty [FILE DESCRIPTOR]
where FILE DESCRIPTOR may be either the number of a file descriptor, or one of the strings stdin, stdout and stderr.
If the specified file descriptor is a tty, the exit status of the command is zero, otherwise, it is non-zero.
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jobs [OPTIONS] [PID]
The jobs builtin causes fish to print a list of the currently running jobs and their status.
jobs accepts the following switches:
-c or --command print the command name for each process in jobs-g or --group only print the group id of each job-h or --help display a help message and exit-l or --last only the last job to be started is printed-p or --pid print the process id for each process in all jobsOn 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%.
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math EXPRESSION
math is used to perform mathematical calculations. It is only a very thin wrapper for the bc program, that makes it possible to specify an expression from the command line without using non-standard extensions or a pipeline. Simply use a command like math 1+1.
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 environment variables or the output of command substitutions, but it also means that parenthesis have to be escaped.
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mimedb [OPTIONS] FILES...
FILES is a list of files to analyse-t, --input-file-data the specified files type should be determined both by their filename and by their contents (Default)-f, --input-filename the specified files type should be determined by their filename-i, --input-mime the arguments are not files but mimetypes-m, --output-mime the output will be the mimetype of each file (Default)-f, --output-description the output will be the description of each mimetype-a, --output-action the output will be the default action of each mimetype-l, --launch launch the default action for the specified file(s)-h, --help display a help message and exit-v, --version display version number and exitThe mimedb command is used to query the mimetype database and the .desktop files installed on the system in order to find information on a file. The information that mimedb can retrieve includes the mimetype for a file, a description of the type and what its default action is. mimedb can also be used to launch the default action for this file.
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nextd [-l | --list] [pos]
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 history is also displayed.
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not COMMAND [OPTIONS...]
The not builtin is used to negate the exit status of another command.
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 FILES...
The open command is used to open a file in its default application. open is implemented using the xdg-open command if it exists, or else the mimedb command.
open *.txt opens all the text files in the current directory using your system's default text editor.
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COMMAND1; or COMMAND2
The or builtin is used to execute a command if the current exit status (as set by the last previous command) is not 0.
The or command 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.
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
popd removes the top directory from the directory stack and cd's to the new top directory.
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prevd [-l | --list] [pos]
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.
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COMMAND1 (COMMAND2|psub [-f])
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. The psub shellscript function, which when 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.
diff (sort a.txt|psub) (sort b.txt|psub) shows the difference between the sorted versions of files a.txt and b.txt.
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pushd [DIRECTORY]
The pushd function adds DIRECTORY to the top of the directory stack and makes it the current directory. Use popd to pop it off and and return to the original directory.
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random [SEED]
The random command is used to generate a random number in the interval 0<=N<32767. If an argument is given, it is used to seed the random number generator. 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.
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 [OPTIONS] [VARIABLES...]
The read builtin causes fish to read one line from standard input and store the result in one or more environment variables.
-c CMD or --command=CMD specifies that the initial string in the interactive mode command buffer should be CMD.-e or --export specifies that the variables will be exported to subshells.-g or --global specifies that the variables will be made global.-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.-p PROMPT_CMD or --prompt=PROMPT_CMD specifies that the output of the shell command PROMPT_CMD should be used as the prompt for the interactive mode prompt. The default prompt command is set_color green; echo read; set_color normal; echo "> ".-s or --shell Use syntax highlighting, tab completions and command termination suitable for entering shellscript code-u or --unexport causes the specified environment not to be exported to child processes-U or --universal causes the specified environment variable to be made universal. 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 environment variable to be exported to child processesRead starts by reading a single line of input from stdin, the line is then tokenized using the IFS environment variable. Each variable specified in VARIABLES is then assigned one tokenized string element. If there are more tokens than variables, the complete remainder is assigned to the last variable.
echo hello|read foo
Will cause the variable $foo to be assigned the value hello.
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function NAME; [COMMANDS...;] return [STATUS]; [COMMANDS...;] end
The return builtin is used to halt a currently running function. 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.
STATUS is the return status of the function. If unspecified, the status is unchanged.The following code is an implementation of the false command as a fish function
function false return 1 end
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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]...
The set builtin causes fish to assign the variable VARIABLE_NAME the values VALUES....
-e or --erase causes the specified environment variable to be erased-l or --local forces the specified environment 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 environment variable to be given a global scope. Non-global variables disappear when the block they belong to ends-U or --universal causes the specified environment 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.-n or --names List only the names of all defined variables, not their value-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.-u or --unexport causes the specified environment not to be exported to child processes-x or --export causes the specified environment variable to be exported to child processesIf set is called with no arguments, the names and values of all environment variables are printed. If some of the scope or export flags have been given, only the variables matching the specified scope are printed.
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:
The exporting rules when creating or updating a variable are identical to the scoping rules for variables:
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. When erasing an entire variable (i.e. no slicing), the scope of the variable to be erased can be specified. That way, a global variable can be erased even if a local variable with the same name exists. Scope can not be specified when erasing a slice of an array. The innermost scope is always used.
The set command requires all switch arguments to come before any non-switch 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 an exit status of zero it the variable assignments where sucessfully performed, with a non-zero exit status otherwise. In query mode, the exit status is the number of variables that where 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.
set -xg will print 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
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set_color [-v --version] [-h --help] [-b --background COLOR] [COLOR]
Change the foreground and/or background color of the terminal. COLOR is one of black, red, green, brown, yellow, blue, magenta, purple, cyan, white and normal.
-b, --background Set the background color-c, --print-colors Prints a list of all valid color names-h, --help Display help message and exit-o, --bold Set bold or extra bright mode-u, --underline Set underlined mode-v, --version Display version and exitCalling set_color normal will set the terminal color to whatever is the default color of the terminal.
Some terminals use the --bold escape sequence to switch to a brighter color set. On such terminals, set_color white will result in a grey font color, while set_color --bold white will result in a white font color.
Not all terminal emulators support all these features. This is not a bug in set_color but a missing feature in the terminal emulator.
set_color 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. Download and install the latest version of ncurses and recompile fish against it in order to fix this issue.
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. FILENAME [ARGUMENTS...]
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 environment variables, etc., will remain. If additional arguments are specified after the file name, they will be inserted into the $argv variable.
If no file is specified, or if the file name '-' is used, stdin will be read.
The return status of . is the return status of the last job to execute. If something goes wrong while opening or reading the file, . exits with a non-zero status.
. ~/.fish
causes fish to reread its initialization file.
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status [OPTION]
-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, i.e.connected to a keyboard-l or --is-login returns 0 if fish is a login shell, i.e. 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 set the job control type. Can be one of: none, full, interactive-t or --print-stack-trace prints a stack trace of all function calls on the call stack-h or --help display a help message and exitBack to index.
switch VALUE; [case [WILDCARD...]; [COMMANDS...]; ...] end
The switch statement is used to perform one of several blocks of commands depending on whether a specified value equals one of several wildcarded values. The case statement is used together with the switch statement in order to determine which block should be performed.
Each case command is given one or more parameter. 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. Though the syntax may look a bit like C switch statements, it behaves more like the case statements of traditional shells.
Also note that command substitutions in a case statement will be evaluated even if it's body is not taken. This may seem counterintuitive at first, but it is unavoidable, since it would be impossible to know if a case command will evaluate to true before all forms of parameter expansion have been performed for the case command.
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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trap [OPTIONS] [[ARG] SIGSPEC ... ]
Trap is a shellscript wrapper around the fish event delivery framework. It exists for backwards compatibility with Posix shells. For other uses, it is recommended to define a event handler.
-h or --help Display help and exit-l or --list-signals print a list of signal names-p or --print print all defined signal handlersIf 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.
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type [OPTIONS] name [name ...]
With no options, indicate how each name would be interpreted if used as a command name.
-h or --help print this message-a or --all print all of possible definitions of the specified names-f or --no-functions suppresses function and builtin lookup-t or --type print a string which is one of alias, keyword, function, builtin, or file if name is an alias, shell reserved word, function, builtin, or disk file, respectively-p or --path either return the name of the disk file that would be executed if name were specified as a command name, or nothing if 'type -t name' would not return 'file'-P or --force-path either return the name of the disk file that would be executed if name were specified as a command name, or nothing no file with the specified name could be found in the PATHtype returns a zero exit status if the specified command was found, otherwise the exit status is one.
type fg outputs the string 'fg is a shell builtin'.
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ulimit [OPTIONS] [LIMIT]
The ulimit builtin is used to set 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.
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's 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. If supported by OS.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 Set hard resource limit-S or --soft Set soft resource limitA hard limit can only be decreased, once it is set it can not 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 Print all current limits-h or --help Display help and exitThe fish implementation of ulimit should behave identically to the implementation in bash, except for these differences:
ulimit -Hs 64
would set the hard stack size limit to 64 kB:
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umask [OPTIONS] [MASK]
With no argument, the current file-creation mask is printed, if an argument is specified, it is the new file creation mask. The mask may be specified as an octal number, in which case it is interpreted as the rights that should be masked away, i.e. it is the inverse of the file permissions any new files will have.
If a symbolic mask is specified, the actual file 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:
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.=, + 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.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.
-h or --help print this message-S or --symbolic prints the file-creation mask in symbolic form instead of octal form. Use man chmod for more information.-p or --as-command prints any output in a form that may be reused as inputThe umask implementation in fish should behave identically to the one in bash.
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 VARIABLE_NAME
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.
vared PATH[3] edits the third element of the PATH array
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while CONDITION; COMMANDS...; end
The while builtin causes fish to continually execute CONDITION and execute COMMANDS as long as CONDITION returned with status 0. If CONDITION is false on the first time, COMMANDS will not be executed at all. Hints: use begin; ...; end for complex conditions; more complex control can be achieved with while true containing a break.
while test -f foo.txt; echo file exists; sleep 10; end
causes fish to print the line 'file exists' at 10 second intervals as long as the file foo.txt exists.
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1.7.6.1