Dtyjlui

I'm trying to automatically run a never ending script (so it doesn't return 0 on exit) at startup on my headless ubuntu 12.04 server with no GUI.

I have tried @reboot nohup /home/luke/netup.sh & in crontab and the script doesn't work properly although it appears to run.
I have tried update-rc.d netup.sh defaults, the script started but still didn't run properly and most of the other programs that are supposed to auto start didn't start.

The script attempts to monitor and record internet outages and contains a while-do loop. It works when logged in to the server and started manually.

Here is the script

#!/bin/bash

#

# Script to monitor internet up time



echo "Server started"  `date "+%F  %T"`  >> /home/luke/netup.log



START=0



while [ 1 ] ; do                    # continuous loop



#------------------------------------------------------------------------

/bin/ping -q 8.8.8.8 -c1 1>/dev/null 2>/dev/null # ping test

PING=$?

#------------------------------------------------------------------------



if [ $PING = 0 ]; then              # ping success

    if [ $START -ne 0 ]; then       # was down

        END=$(date +%s)

        TIME=$(($END - $START))

        START=0

        let TIME=($TIME/60)     #convert seconds to minutes

        echo "Failed" $FAIL_TIME "for" $TIME "minutes" >> /home/luke/netup.log



    fi



else                        # ping failure

    if [ $START -eq 0 ]; then       # was up

        START=$(date +%s)

        FAIL_TIME=$(date "+%F  %T")

    fi



fi



#------------------------------------------------------------------------

if [ $PING = 0 ]; then              # wait



    sleep 60

else

    sleep 10

fi



done

Rather than setting up a script to run constantly at startup, why not change it to run using cron? Since you are telling it to sleep for 60 seconds between runs anyway, using cron to run a script without a while loop once a minute would make more sense and be simpler to manage.

You might also be interested in the answers for this question on serverfault:

https://serverfault.com/questions/49082/can-i-run-a-cron-job-more-frequently-than-every-minute