fish-shell/doc_src/function.txt
David Adam (zanchey) 1287b9d823 Help cleanup
Large list of changes, including formatting and typos for most commands.

More substantive changes have been made to alias, bind, block, break,
builtin, case, cd, commandline, count, else, emit, fish_config, funced,
function, functions, history, math, mimedb, nextd, not, popd, prevd,
pushd, pwd, random, read, set, set_color, switch, test, trap, type,
ulimit, umask, and while.
2013-05-13 01:48:20 -07:00

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\section function function - create a function
\subsection function-synopsis Synopsis
<code>function [OPTIONS] NAME; BODY; end </code>
\subsection function-description Description
\c function creates a new function \c NAME with the body <code>BODY</code>.
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:
- <code>-d DESCRIPTION</code> or \c --description=DESCRIPTION is a description of what the function does, suitable as a completion description.
- <code>-e</code> or <code>--on-event EVENT_NAME</code> tells fish to run this function when the specified named event is emitted. Fish internally generates named events e.g. when showing the prompt.
- <code>-j PID</code> or <code> --on-job-exit PID</code> 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.
- <code>-p PID</code> or <code> --on-process-exit PID</code> tells fish to run this function when the fish child process with process ID PID exits.
- <code>-s</code> or <code>--on-signal SIGSPEC</code> 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).
- <code>-v</code> or <code>--on-variable VARIABLE_NAME</code> tells fish to run this function when the variable VARIABLE_NAME changes value.
If the user enters any additional arguments after the function, they
are inserted into the environment <a href="index.html#variables-arrays">variable array</a>
<code>$argv</code>.
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</a> builtin. Fish generates the following named events:
- \c fish_prompt, which is emitted whenever a new fish prompt is about to be displayed.
- \c fish_command_not_found, which is emitted whenever a command lookup failed.
\subsection function-example Example
<pre>
function ll
ls -l $argv
end
</pre>
will run the \c ls command, using the \c -l option, while passing on any additional files and switches to \c ls.
<pre>
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
</pre>
will run the mkdir command, and if it is successful, change the
current working directory to the one just created.