Fis systemd support on debian system version 13 (trixie) or newer.

install_postfwd.sh

@@ -65,6 +65,14 @@ echo_skipped() {
    echo -e "\033[80G[ \033[33m\033[1mskipped\033[m ]"
 }
 
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
+   systemd_exists=true
+fi
+
 ## - Install Postfix Firewall Daemon from debian packages system
 ## -
 echononl "   Install Postfix Firewall Daemon from debian packages system"