Starting a Linux process only if it isn't started

[drewdavis]

I am writing a bash script that launches a service (in my case nagios). I want to start my script by running /etc/init.d/nagios start only if nagios is not running.

I start my script with

/etc/init.d/nagios stop
/etc/init.d/nagios start
...

I'm not sure it is the best way to go, I'd rather use an if statement. Any ideas ?

[bbahn]

Hello @drewdavis,

You can definitely accomplish what you're thinking of using something like the following:

Code: Select all

# Check if Nagios is running with /etc/init.d/nagios status, pgrep, systemctl status, ps aux | grep, etc.

# $? holds the exit status of the last command
if [ $? -ne 0 ]; then
    echo "Nagios is not running. Starting Nagios..."
    /etc/init.d/nagios start
else
    echo "Nagios is already running."
fi