examples/functions/whence

#
# An almost-ksh compatible `whence' command.  This is as hairy as it is 
# because of the desire to exactly mimic ksh.
# 
# This depends somewhat on knowing the format of the output of the bash
# `builtin type' command.
#
# Chet Ramey
# chet@ins.CWRU.Edu
#
#
#  Chet Ramey <chet.ramey@case.edu>
#
#  Copyright 1994 Chester Ramey
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 2, or (at your option)
#   any later version.
#
#   TThis program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software Foundation,
#   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

whence()
{
	local vflag= path=

	if [ "$#" = "0" ] ; then
		echo "whence: argument expected"
		return 1
	fi
	case "$1" in
		-v) vflag=1
		    shift 1
		    ;;
		-*) echo "whence: bad option: $1"
		    return 1
		    ;;
		 *) ;;
	esac

	if [ "$#" = "0" ] ; then
		echo "whence: bad argument count"
		return 1
	fi

	for cmd
	do
		if [ "$vflag" ]	 ; then
			echo $(builtin type $cmd | sed 1q)
		else
			path=$(builtin type -path $cmd)
			if [ "$path" ] ; then
				echo $path
			else
				case "$cmd" in
					/*) if [ -x "$cmd" ]; then
						echo "$cmd"
					    fi
					    ;;
					 *) case "$(builtin type -type $cmd)" in
						"") ;;
						 *) echo "$cmd"
						    ;;
					    esac
					    ;;
				esac
			fi
		fi
	done
	return 0
}