bash - Linux Script to check if process is running and act on the result

Question

I have a process that fails regularly & sometimes starts duplicate instances..

When I run: ps x |grep -v grep |grep -c "processname" I will get: 2 This is normal as the process runs with a recovery process..

If I get 0 I will want to start the process if I get: 4 I will want to stop & restart the process

What I need is a way of taking the result of ps x |grep -v grep |grep -c "processname"

Then setup a simple 3 option function

ps x |grep -v grep |grep -c "processname"
if answer = 0 (start process & write NOK & Time to log /var/processlog/check)
if answer = 2 (Do nothing & write OK & time to log /var/processlog/check)
if answer = 4 (stot & restart the process & write NOK & Time to log /var/processlog/check)

The process is stopped with killall -9 process The process is started with process -b -c /usr/local/etc

My main problem is finding a way to act on the result of ps x |grep -v grep |grep -c "processname".

Ideally, I would like to make the result of that grep a variable within the script with something like this:

process=$(ps x |grep -v grep |grep -c "processname")

If possible.

Answer 1

Programs to monitor if a process on a system is running.

Script is stored in crontab and runs once every minute.

This works with if process is not running or process is running multiple times:

#! /bin/bash

case "$(pidof amadeus.x86 | wc -w)" in

0)  echo "Restarting Amadeus:     $(date)" >> /var/log/amadeus.txt
    /etc/amadeus/amadeus.x86 &
    ;;
1)  # all ok
    ;;
*)  echo "Removed double Amadeus: $(date)" >> /var/log/amadeus.txt
    kill $(pidof amadeus.x86 | awk '{print $1}')
    ;;
esac

0 If process is not found, restart it.
1 If process is found, all ok.
* If process running 2 or more, kill the last.

---

A simpler version. This just test if process is running, and if not restart it.

It just tests the exit flag $? from the pidof program. It will be 0 of process is running and 1 if not.

#!/bin/bash
pidof  amadeus.x86 >/dev/null
if [[ $? -ne 0 ]] ; then
        echo "Restarting Amadeus:     $(date)" >> /var/log/amadeus.txt
        /etc/amadeus/amadeus.x86 &
fi

---

And at last, a one liner

pidof amadeus.x86 >/dev/null ; [[ $? -ne 0 ]] && echo "Restarting Amadeus:     $(date)" >> /var/log/amadeus.txt && /etc/amadeus/amadeus.x86 &

cccam oscam