diff --git a/create-update-postfix-pcre-chek-files.sh b/create-update-postfix-pcre-chek-files.sh
index eccc5dd..37ea03d 100755
--- a/create-update-postfix-pcre-chek-files.sh
+++ b/create-update-postfix-pcre-chek-files.sh
@@ -115,9 +115,11 @@ DEFAULT_ADMIN_EMAIL="argus@oopen.de"
 
 # - Is this a systemd system?
 # -
-if [[ "X`which systemd`" = "X" ]]; then
-   systemd_exists=false
-else
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    systemd_exists=true
 fi
 
diff --git a/install_amavis.sh b/install_amavis.sh
index 5481b98..348bc9d 100755
--- a/install_amavis.sh
+++ b/install_amavis.sh
@@ -154,9 +154,11 @@ QUARANTINE_ADMIN=$DEFAULT_QUARANTINE_ADMIN
 
 # - Is this a systemd system?
 # -
-if [[ "X`which systemd`" = "X" ]]; then
-   systemd_exists=false
-else
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    systemd_exists=true
 fi
 
diff --git a/install_opendkim.sh b/install_opendkim.sh
index 9b85d7a..b1e2adf 100755
--- a/install_opendkim.sh
+++ b/install_opendkim.sh
@@ -94,9 +94,11 @@ echo_skipped() {
 
 # - Is 'systemd' supported on this system
 # -
-if [ "X`which systemd`" = "X" ]; then
-   SYSTEMD_EXISTS=false
-else
+SYSTEMD_EXISTS=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    SYSTEMD_EXISTS=true
 fi
 
diff --git a/install_opendmarc.sh b/install_opendmarc.sh
index dafd81d..c33c530 100755
--- a/install_opendmarc.sh
+++ b/install_opendmarc.sh
@@ -116,9 +116,11 @@ echo_skipped() {
 
 # - Is 'systemd' supported on this system
 # -
-if [ "X`which systemd`" = "X" ]; then
-   SYSTEMD_EXISTS=false
-else
+SYSTEMD_EXISTS=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    SYSTEMD_EXISTS=true
 fi
 
diff --git a/install_postfix_advanced.sh b/install_postfix_advanced.sh
index f43ad79..d7d0c89 100755
--- a/install_postfix_advanced.sh
+++ b/install_postfix_advanced.sh
@@ -136,9 +136,11 @@ DEFAULT_INSTALL_DMARC_REPORT_SUPPORT=false
 
 # - Is this a systemd system?
 # -
-if [[ "X`which systemd`" = "X" ]]; then
-   systemd_exists=false
-else
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    systemd_exists=true
 fi
 
diff --git a/install_postfix_base.sh b/install_postfix_base.sh
index f8f4a02..2286054 100755
--- a/install_postfix_base.sh
+++ b/install_postfix_base.sh
@@ -136,9 +136,11 @@ DEFAULT_REWRITE_SENDER_DOMAIN=None
 
 # - Is this a systemd system?
 # -
-if [[ "X`which systemd`" = "X" ]]; then
-   systemd_exists=false
-else
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    systemd_exists=true
 fi
 
diff --git a/install_postfwd.sh b/install_postfwd.sh
index 3b43db2..beec916 100755
--- a/install_postfwd.sh
+++ b/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"
diff --git a/install_update_dovecot-2.4.sh b/install_update_dovecot-2.4.sh
index 5484cd7..670e337 100755
--- a/install_update_dovecot-2.4.sh
+++ b/install_update_dovecot-2.4.sh
@@ -964,9 +964,11 @@ delete_variable_with_comments() {
 
 # - Support systemd ?
 # -
-if [[ "X$(which systemd)" = "X" ]]; then
-   SYSTEMD_EXISTS=false
-else
+SYSTEMD_EXISTS=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    SYSTEMD_EXISTS=true
 fi
 
diff --git a/install_update_dovecot.sh b/install_update_dovecot.sh
index 63a341d..ab60c35 100755
--- a/install_update_dovecot.sh
+++ b/install_update_dovecot.sh
@@ -148,9 +148,11 @@ detect_os_1 () {
 
 # - Support systemd ?
 # -
-if [[ "X$(which systemd)" = "X" ]]; then
-   SYSTEMD_EXISTS=false
-else
+SYSTEMD_EXISTS=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    SYSTEMD_EXISTS=true
 fi
 
diff --git a/install_vacation.sh b/install_vacation.sh
index 4b4ff22..47630a5 100755
--- a/install_vacation.sh
+++ b/install_vacation.sh
@@ -95,6 +95,16 @@ echo_skipped() {
    echo -e "\033[75G[ \033[30m\033[1mskipped\033[m ]"
 }
 
+# -Is systemd supported on this system?
+# -
+systemd_supported=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
+   systemd_supported=true
+fi
+
 
 if [ "$POSTFIX_DB_TYPE" = "postgres" -o  "$POSTFIX_DB_TYPE" = "postgresql" -o "$POSTFIX_DB_TYPE" = "pgsql" -o "$POSTFIX_DB_TYPE" = "psql" ];then
    POSTFIX_DB_TYPE=pgsql
diff --git a/update_clamav-unofficial-sigs.sh b/update_clamav-unofficial-sigs.sh
index cba3b53..0cd7daf 100755
--- a/update_clamav-unofficial-sigs.sh
+++ b/update_clamav-unofficial-sigs.sh
@@ -182,9 +182,11 @@ fi
 
 # - Is this a systemd system?
 # -
-if [[ "X`which systemd`" = "X" ]]; then
-   systemd_exists=false
-else
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    systemd_exists=true
 fi
 
diff --git a/update_postfix_dh_parameters.sh b/update_postfix_dh_parameters.sh
index 7c5d488..2e7d046 100755
--- a/update_postfix_dh_parameters.sh
+++ b/update_postfix_dh_parameters.sh
@@ -126,9 +126,11 @@ DEFAULT_SASL_AUTH=false
 
 # - Is this a systemd system?
 # -
-if [[ "X`which systemd`" = "X" ]]; then
-   systemd_exists=false
-else
+systemd_exists=false
+systemd=$(which systemd)
+systemctl=$(which systemctl)
+
+if [[ -n "$systemd" ]] || [[ -n "$systemctl" ]] ; then
    systemd_exists=true
 fi