serv: add systemd detect

bin/serv

 #!/bin/sh
 #
-# Copyright (C) 2012  Etersoft
-# Copyright (C) 2012  Vitaly Lipatov <lav@etersoft.ru>
+# Copyright (C) 2012-2013  Etersoft
+# Copyright (C) 2012-2013  Vitaly Lipatov <lav@etersoft.ru>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
@@ -50,6 +50,13 @@ set_service_type()
 	[ -n "$DISTRVERSION" ] || DISTRVERSION=$($DISTRVENDOR -v)
 	set_target_pkg_env
 
+is_active_systemd()
+{
+	SYSTEMCTL=/bin/systemctl
+	SYSTEMD_CGROUP_DIR=/sys/fs/cgroup/systemd
+	[ -x "$SYSTEMCTL" ] && [ -d "$SYSTEMD_CGROUP_DIR" ] && mountpoint -q "$SYSTEMD_CGROUP_DIR"
+}
+
 case $DISTRNAME in
 	ALTLinux)
 		CMD="service-chkconfig"
@@ -85,6 +92,10 @@ case $DISTRNAME in
 		fatal "Do not known DISTRNAME $DISTRNAME yet"
 		;;
 esac
+
+# Note: force systemd using if active
+is_active_systemd && CMD="systemd"
+
 SERVICETYPE=$CMD
 }