diff --git a/sh/main.sh b/sh/main.sh
index 6c18b48..692664a 100644
--- a/sh/main.sh
+++ b/sh/main.sh
@@ -74,6 +74,13 @@ sh_help() {
 		"u__… = user"
 }
 
+sh_shell_interactive() {
+	case "${-}" in
+	*i*) ;;
+	*) return 1 ;;
+	esac
+}
+
 sh_source_directory() {
 	local path="${1}"
 	[ -d "${path}" ] ||