examples/functions/substr

#
#  Chet Ramey <chet.ramey@case.edu>
#
#  Copyright 2002 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.
#
# substr -- a function to emulate the ancient ksh builtin
#

#
# -l == shortest from left
# -L == longest from left
# -r == shortest from right (the default)
# -R == longest from right

substr()
{
	local flag pat str
	local usage="usage: substr -lLrR pat string or substr string pat"

	case "$1" in
	-l | -L | -r | -R)
		flag="$1"
		pat="$2"
		shift 2
		;;
	-*)
		echo "substr: unknown option: $1"
		echo "$usage"
		return 1
		;;
	*)
		flag="-r"
		pat="$2"
		;;
	esac

	if [ "$#" -eq 0 ] || [ "$#" -gt 2 ] ; then
		echo "substr: bad argument count"
		return 2
	fi

	str="$1"

	#
	# We don't want -f, but we don't want to turn it back on if
	# we didn't have it already
	#
	case "$-" in
	"*f*")
		;;
	*)
		fng=1
		set -f
		;;
	esac

	case "$flag" in
	-l)
		str="${str#$pat}"		# substr -l pat string
		;;
	-L)
		str="${str##$pat}"		# substr -L pat string
		;;
	-r)
		str="${str%$pat}"		# substr -r pat string
		;;
	-R)
		str="${str%%$pat}"		# substr -R pat string
		;;
	*)
		str="${str%$2}"			# substr string pat
		;;
	esac

	echo "$str"

	#
	# If we had file name generation when we started, re-enable it
	#
	if [ "$fng" = "1" ] ; then
		set +f
	fi
}