\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.