Bash shell script to check if script itself is running

hi guys

we've had nagios spewing false alarm (for the umpteenth time) and finally the customer had enough so they're starting to question nagios. we had the check interval increased from 5 minutes to 2 minutes, but that's just temporary solution. I'm thinking of implementing a script on the affected client servers that monitors the processes, and if its not running it will use Logger to produce a string of sentence that I can easily pick up with nagios monitoring. all i have to do then is just add the "key words" into nagios check configuration which already monitors /var/log/messages

So the script that looks for process to check if its running or not is as such:

# more /usr/local/bin/process
#!/bin/bash
PROCESS="httpd" 

if /etc/init.d/$PROCESS status | grep running.> /dev/null 
then 
logger -s "$PROCESS is running" 
else 
logger -s "$PROCESS is not running" 
fi

so how do i monitor to see if the script itself is running? I tried with ps -ef but you know ps is still going to show me two lines (one with ps, the other if script is running) so its not really a good way to check, isnt it?

when i put the job in the background with nohup and grep with ps aux I get nothing

# ps aux | grep /usr/local/bin/process | grep -v /usr/local/bin/process | wc -l
0

Can someone please help me out?

If you have pgrep installed, it might be what you need:

$ pgrep -l rsyslogd
1515 rsyslogd

@hergp im going try that out and update here with my full script when im done! thanks!

---------- Post updated at 11:05 AM ---------- Previous update was at 10:18 AM ----------

@hergp

the command works well for grep but how do i check if the script itself is running? when i run my script as such

 "nohup /usr/local/bin/process &" 

and i opened another terminal and grepped the job but the result is still empty grep. so how can i check and confirm the script itself is running?

I see your script is checking if the process is running, using logger to log the status and terminating. This is the reason why you are not seeing it running. You should put this in an infinite while loop with a sleep time of your choice for periodically checking and logging the status.

E.g:-

#!/bin/bash
PROCESS="httpd" 

while (true)
do
if /etc/init.d/$PROCESS status | grep running.> /dev/null 
then 
      logger -s "$PROCESS is running" 
else 
      logger -s "$PROCESS is not running" 
fi
sleep 300
done

Now you can start your script using nohup and open another terminal to check if it is running:-

nohup /usr/local/bin/process &

ps -eaf | grep /usr/local/bin/process | grep -v grep

I hope this helps.

@bipin

the grep command totally didn't work, i am still getting empty result when i grep

[root@hedkandi bin]# nohup /usr/local/bin/test &
[1] 14194
[root@hedkandi bin]# nohup: ignoring input and appending output to `nohup.out'

[root@hedkandi ~]# ps -eaf | grep /usr/local/bin/process | grep -v grep
[root@hedkandi ~]# 

if i use flock i can see messages in my /var/log but how do i ensure that it only gets written into if a. the script is running b. the script is not running c. the process is running d. the process is not running

#!/bin/bash
SERVICE="httpd"
CHECK_SCRIPT="/usr/local/bin/process"

if flock -n /var/run/your.lockfile -c /usr/local/bin/process >/dev/null
    then
logger -s "$CHECK_SCRIPT is running. Do nothing"
    else
logger -s "$CHECK_SCRIPT is not running. Please restart script"
    fi

if pgrep -l $SERVICE | grep $SERVICE  >/dev/null
    then
logger -s "$SERVICE process is running. Do nothing"
    else
logger -s "$SERVICE process is not running. Please restart service"
    fi

now, this script only detects the script is running and if the process is running/not running...a little help please to make it reliase the script is not running

I see you renamed the script to test, running it and later grepping for script named process. That does not make any sense!

OMG bipin you're totally right. hang on let me try this again.

so heres whats happening.

If i run the script after starting httpd i get this:

Nov  4 23:56:06 hedkandi root: /usr/local/bin/test is not running. Please restart script--this isnt right, it should be showing /usr/local/bin/test is running. Do nothing
Nov  4 23:56:06 hedkandi root: httpd process is not running. Please restart service

If i run the script after stopping httpd I get this:

Nov  4 23:56:06 hedkandi root: /usr/local/bin/test is running. Do nothing
Nov  4 23:56:06 hedkandi root: httpd process is not running. Please restart service

and the other two thing thats totally not working is if

i stop script and process is running it should give me a

/usr/local/bin/test is not running. Please restart script
httpd process is running. Do nothing

if i stop script and stop process it should give me a

/usr/local/bin/test is not running. Please restart script
httpd process is not running. Please restart service

Please modify your if-else statement like below and re-try:-

if [ `ps -eaf | grep -v grep | grep -c $CHECK_SCRIPT` -ne 0 ]
then
      logger -s "$CHECK_SCRIPT is running. Do nothing"
else
      logger -s "$CHECK_SCRIPT is not running. Please restart script"
fi           

if [ `pgrep -l $SERVICE | grep -c $SERVICE` -ne 0 ]
then
      logger -s "$SERVICE process is running. Do nothing"
else
      logger -s "$SERVICE process is not running. Please restart service"
fi

@bipin, thank you so very much
that did it!

just in case if anyone needs a script that checks if itself is running/not running as well as the process its meant to check if its running/not running

#!/bin/bash
SERVICE="httpd"
CHECK_SCRIPT="/usr/local/bin/test"

if [ `ps -eaf | grep -v grep | grep -c $CHECK_SCRIPT` -ne 0 ]
    then
logger -s "$CHECK_SCRIPT is running. Do nothing"
    else
logger -s "$CHECK_SCRIPT is not running. Please restart script"
    fi

if  [ `pgrep -l $SERVICE | grep -c $SERVICE` -ne 0 ]
    then
logger -s "$SERVICE process is running. Do nothing"
    else
logger -s "$SERVICE process is not running. Please restart service"
    fi

i have this in crontab and runs at the interval of 5 mins