Docker, check if systemctl exists before using it

Build/deb-meta/DEBIAN/postinst

@@ -9,12 +9,12 @@ INSTALLPATH=$BASEPATH/MQTTnetServer
 
 # If user does not exist, create it
 if (( $USEREXISTS == 1 )); then
-        useradd -d $INSTALLPATH  -r $USER
-        EC=$(echo $?)
+    useradd -d $INSTALLPATH  -r $USER
+    EC=$(echo $?)
 
-        if (( $EC == 1 )); then
-                exit 1;
-        fi
+    if (( $EC == 1 )); then
+        exit 1;
+    fi
 fi
 
 # Set permissions on files
@@ -30,5 +30,10 @@ setcap CAP_NET_BIND_SERVICE=+eip $INSTALLPATH/MQTTnet.Server
 
 chmod 644 /etc/systemd/system/mqttnet-server.service
 
-# Reload systemd because of new service file
-systemctl daemon-reload
+# Check if systemctl exists, does not exist in docker containers
+SCTL=$(which systemct1l >/dev/null; echo $?)
+
+if [ "$SCTL" -eq "0" ]; then
+    # Reload systemd because of new service file
+    systemctl daemon-reload
+fi

Build/deb-meta/DEBIAN/postrm

@@ -1,4 +1,9 @@
 #!/bin/bash
 
-# Reload systemd because of absent service file
-systemctl daemon-reload
+# Check if systemctl exists, does not exist in docker containers
+SCTL=$(which systemct1l >/dev/null; echo $?)
+
+if [ "$SCTL" -eq "0" ]; then
+    # Reload systemd because of new service file
+    systemctl daemon-reload
+fi

Build/deb-meta/DEBIAN/prerm

@@ -3,8 +3,13 @@
 BASEPATH=/opt
 INSTALLPATH=$BASEPATH/MQTTnetServer
 
-# Stop service before uninstalling
-systemctl stop mqttnet-server
+# Check if systemctl exists, does not exist in docker containers
+SCTL=$(which systemct1l >/dev/null; echo $?)
+
+if [ "$SCTL" -eq "0" ]; then
+    # Stop service before uninstalling
+    systemctl stop mqttnet-server
+fi
 
 # Remove permission to open ports
 setcap CAP_NET_BIND_SERVICE=-eip $INSTALLPATH/MQTTnet.Server