Added a check to see if docker is installed before attempting to get its version

Author: Slyke

menu.sh

@@ -182,21 +182,25 @@ fi
 
 #---------------------------------------------------------------------------------------------------
 # Docker updates
-echo "checking docker version"
-SERVER_VERSION=$(docker version -f "{{.Server.Version}}")
-SERVER_VERSION_MAJOR=$(echo "$SERVER_VERSION"| cut -d'.' -f 1)
-SERVER_VERSION_MINOR=$(echo "$SERVER_VERSION"| cut -d'.' -f 2)
-SERVER_VERSION_BUILD=$(echo "$SERVER_VERSION"| cut -d'.' -f 3)
-
-if [ "${SERVER_VERSION_MAJOR}" -ge 18 ] && \
-	[ "${SERVER_VERSION_MINOR}" -ge 2 ]  && \
-	[ "${SERVER_VERSION_BUILD}" -ge 0 ]; then
-	echo "Docker version >= 18.2.0. You are good to go."
+if command_exists docker; then
+	echo "checking docker version"
+	SERVER_VERSION=$(docker version -f "{{.Server.Version}}")
+	SERVER_VERSION_MAJOR=$(echo "$SERVER_VERSION"| cut -d'.' -f 1)
+	SERVER_VERSION_MINOR=$(echo "$SERVER_VERSION"| cut -d'.' -f 2)
+	SERVER_VERSION_BUILD=$(echo "$SERVER_VERSION"| cut -d'.' -f 3)
+
+	if [ "${SERVER_VERSION_MAJOR}" -ge 18 ] && \
+		[ "${SERVER_VERSION_MINOR}" -ge 2 ]  && \
+		[ "${SERVER_VERSION_BUILD}" -ge 0 ]; then
+		echo "Docker version >= 18.2.0. You are good to go."
+	else
+		echo ""
+		echo "Docker version less than 18.02.0 consider upgrading or you may experience issues"
+		echo "Upgrade by typing: 'sudo apt upgrade docker docker-compose'"
+		sleep 2
+	fi
 else
-	echo ""
-	echo "Docker version less than 18.02.0 consider upgrading or you may experience issues"
-	echo "Upgrade by typing: 'sudo apt upgrade docker docker-compose'"
-	sleep 2
+	echo "docker not installed"
 fi
 
 #---------------------------------------------------------------------------------------------------