wmenu/wmenu_run

#!/bin/sh

cachedir="${XDG_CACHE_HOME:-"$HOME/.cache"}"
cache="$cachedir/wmenu_run"

[ -d "$cachedir" ] || mkdir -p "$cachedir"

uptodate() {
	[ -f "$cache" ] || return 1
	IFS=:
	for path in $PATH; do
		# non-POSIX
		test "$path" -nt "$cache" && return 1
	done
	return 0
}

bins() {
	IFS=:
	for path in $PATH; do
		for bin in "$path"/*; do
			[ -x "$bin" ] && echo "${bin##*/}"
		done
	done
}

path() {
	if uptodate; then
		cat "$cache"
	else
		bins | sort -u | tee "$cache"
	fi
}

path | wmenu "$@" | ${SHELL:-"/bin/sh"} &