Check service status in real-time

Question

I'd like to check the status of a service in real-time.

I already know the command to check for example my Homebridge server:

/etc/init.d/homebridge status

When I'm debugging, I'd like to see the change of the status (for example running -> stopped) immediately.

Is there a command to keep track of this status in real-time, so I don't need to type in the command continuously?

Answer 1

You can use the watch utility to continuously update the status without using a loop.

watch --interval 1 'date; /etc/init.d/homebridge status'

which will update every second (the default is two seconds).

Answer 2

You can get a continuous listing of a file with tail -f. I'm not familiar with your specific service, but according what I see online, it keeps two logs at /var/log/homebridge.log and /var/log/homebridge.err. You would then get the non-error log with this complete command:

tail -f /var/log/homebridge.log

(or add sudo before the whole line if necessary given your permissions).

Answer 3

Systemd tracks the processes attached to most persistent services, although I am not sure how well with regard to those controlled by old school SysV scripts, as homebridge appears to be.

In any case, a simple shell script like this will report that tracking information, including the point at which a process dies/exits for whatever reason.

#!/bin/sh

while true; do
    clear
    date
    systemctl status $1
    sleep 3
done 

Call that monitor.sh and run it monitor.sh homebridge. The time reported by date will change every three seconds if nothing else does. Note this will occupy a terminal until you stop it with Ctrl-C.