Ubuntu 20.04. and previos version (Nagios 4 nad 3)

There is a bug in the "restart" function in the /etc/init.d/nagios4 systemd script that causes the restart to fail.

if [ -z "$?" -o "$?" = "0" ] - second use -o "$?" should check the stop function, but check the result -z "$?"
To resolve this issue, perform the following modification.

@@ -223,11 +223,13 @@
;;
restart)
log_daemon_msg "Restarting $DESC" "$NAME"
- stop
- if [ -z "$?" -o "$?" = "0" ]; then
+ stop
+ STOP_STATUS=$?
+ if [ "$STOP_STATUS" -eq 0 ]; then
start
+ START_STATUS=$?
fi
- log_end_msg $?
+ log_end_msg $START_STATUS
;;
reload|force-reload)
log_daemon_msg "Reloading $DESC configuration files" "$NAME"

(I don't know if this thread is the right place )