substr2

linux下bash的源码

#
# substr -- a function to emulate the ancient ksh builtin
#

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

substr()
{
	local flag pat str
	local usage="usage: substr -lLrR pat string or substr string pat"
	local options="l:L:r:R:"

	OPTIND=1
	while getopts "$options" c
	do
		case "$c" in
		l | L | r | R)
			flag="-$c"
			pat="$OPTARG"
			;;
		'?')
			echo "$usage"
			return 1
			;;
		esac
	done

	if [ "$OPTIND" -gt 1 ] ; then
		shift $[ $OPTIND -1 ]
	fi

	if [ "$#" -eq 0 -o "$#" -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
}