dmenu/dmenu_run

#!/bin/sh
cachedir=${XDG_CACHE_HOME:-"$HOME/.cache"}
if [ -d "$cachedir" ]; then
	cache=$cachedir/dmenu_run
else
	cache=$HOME/.dmenu_cache # if no xdg dir, fall back to dotfile in ~
fi
(
	IFS=:
	if [ "`ls -dt $PATH "$cache" | head -n 1`" != "$cache" ]; then
		lsx $PATH | sort -u | tee "$cache" | dmenu "$@"
	else
		dmenu "$@" < "$cache"
	fi
) | ${SHELL:-"/bin/sh"} &