Added help message to Linux systems.

(Assuming Linux uses gnu coreutils with --help,
and non-Linux doesn't.)

ls_zero.bash

@@ -3,12 +3,27 @@ _ls() {
 	env ls "$@"
 }
 
+matchtest() {
+	printf "%s" "$1" | grep -qE "$2"
+}
+
 _lsp() {
-	printf "%s" "$*" | grep -qE '(^| )--zero( |$)'
+	if matchtest "$(uname)" "Linux" && matchtest "$*" '(^| )(-h|--help)( |$)'; then
+		_ls "$@"
+		local error=$?
+		test $error -eq 0 && cat <<- EOF
+			ls zero bash polyfill:
+			    adds additional --zero option, which seperates
+			    output with null characters rather than newlines
+			    use _ls or env ls for default behavior
+		EOF
+		return $error
+	fi
+	matchtest "$*" '(^| )--zero( |$)'
 	local zero=$?
 	local args="$@"
 	declare -a args=(${args[@]/--zero/})
-	if test "$zero" -eq 0; then
+	if test $zero -eq 0; then
 		output="$(_ls "${args[@]}")"
 		error=$?
 		printf "%s" "$output" | tr '\n' '\0'