fish-shell/doc_src/function.txt

\section function function - create a function

\subsection function-synopsis Synopsis
 <tt>function [OPTIONS] NAME; BODY; end </tt>

\subsection function-description Description

- \c -b or \c --key-binding specifies that the function is a key biding. Key binding functions work exactly like regular functions except that they can not be tab-completed, and may contain the '-' character. 
- <tt>-d DESCRIPTION</tt> or \c --description=DESCRIPTION is a description of what the function does, suitable as a completion description
- <tt>-j PID</tt> or <tt> --on-job-exit PID</tt> tells fish to run this function when the job with group id PID exits
- <tt>-p PID</tt> or <tt> --on-process-exit PID</tt> tells fish to run this function when the fish child process with process id PID exits
- <tt>-s</tt> or <tt>--on-signal SIGSPEC</tt> tells fish to run this function when the signal SIGSPEC is delivered. SIGSPEC can be a singal number, or the signal name, such as SIGHUP (or just HUP)
- <tt>-v</tt> or <tt>--on-variable VARIABLE_NAME</tt> tells fish to run this function when the variable VARIABLE_NAME changes value

This 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 

<pre>
function hi
	echo hello
end
</pre> 

will write <tt>hello</tt> whenever the user enters \c hi.

If the user enters any additional arguments after the function, they
are inserted into the environment variable <a href="index.html#variables-arrays">array</a> argv.

\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"
	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 succesfull, change the
current working directory to the one just created.