rc/sh/witch

#!/usr/bin/env sh
# FAKE_COMPAT
### @ witch
### this is a personal rewrite of `which` from Debian.
### the original version didn't run on certain shells,
### and inherited inconsistent behaviors from getopts.

set -ef

all=0
for flag; do
	case "$flag" in
	(--) shift; break;;
	(-?*)
		shift
		while flag="${flag#?}"; [ -n "$flag" ]; do
			case "$flag" in
			(a*) all=1;;
			(*)
				printf >&2 'Illegal option: -%.1s\n' "$flag"
				printf 'Usage: %s\n' "$0 [-a] args"
				exit 2;;
			esac
		done;;
	(*) break
	esac
done

[ "$#" = 0 ] && res=1 || res=0

IFS=:
for prog; do
	err=1
	case "$prog" in
	(*/*)
		if [ -f "$prog" ] && [ -x "$prog" ]; then
			printf %s\\n "$prog"
			err=0
		fi;;
	(*)
		set -- $(printf %s: "$PATH")
		for sub; do
			[ -n "$sub" ] || sub=.
			if [ -f "$sub/$prog" ] && [ -x "$sub/$prog" ]; then
				printf %s\\n "$sub/$prog"
				err=0
				[ "$all" = 1 ] || break
			fi
		done;;
	esac
	[ "$err" = 0 ] || res=1
done

exit "$res"