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 & 

This can then be used in crontab to run every minute like this:

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

cccam oscam

Answer 2

I adopted the @Jotne solution and works perfectly! For example for mongodb server in my NAS

#! /bin/bash  case "$(pidof mongod | wc -w)" in  0)  echo "Restarting mongod:"     mongod --config mongodb.conf     ;; 1)  echo "mongod already running"     ;; esac 

Answer 3

I have adopted your script for my situation Jotne.

#! /bin/bash

logfile="/var/oscamlog/oscam1check.log"

case "$(pidof oscam1 | wc -w)" in

0)  echo "oscam1 not running, restarting oscam1:     $(date)" >> $logfile
    /usr/local/bin/oscam1 -b -c /usr/local/etc/oscam1 -t /usr/local/tmp.oscam1 &
    ;;
2)  echo "oscam1 running, all OK:     $(date)" >> $logfile
    ;;
*)  echo "multiple instances of oscam1 running. Stopping & restarting oscam1:     $(date)" >> $logfile
    kill $(pidof oscam1 | awk '{print $1}')
    ;;
esac

While I was testing, I ran into a problem.. I started 3 extra process's of oscam1 with this line: /usr/local/bin/oscam1 -b -c /usr/local/etc/oscam1 -t /usr/local/tmp.oscam1 which left me with 8 process for oscam1. the problem is this.. When I run the script, It only kills 2 process's at a time, so I would have to run it 3 times to get it down to 2 process..

Other than killall -9 oscam1 followed by /usr/local/bin/oscam1 -b -c /usr/local/etc/oscam1 -t /usr/local/tmp.oscam1, in *)is there any better way to killall apart from the original process? So there would be zero downtime?