Scheduling cron job

Linux and Unix-Like Red Hat
1

Hi Everybody,

I want to run a script at every 5 seconds. I know how to run it every 5 minutes, is there any possibility to run a script at 5 seconds interval.

Regards,
Mastan

2

Possibly better to wrap your script as a loop, e.g.

#!/bin/ksh
lastsec=-1         # Set to an invalid second count to ensure an immediate start.
while true
do
   currsec=`date +%S`
   ((testsec=$currsec/5))
   ((testsec=$testsec*5))
   if [ $testsec -eq $currsec -a $testsec -ne $lastsec ]
   then
      run-your-code-here
   else
      sleep 1
   fi
   lastsec=$currsec
done

Of course, this never ends unless you put an exit in the code somewhere. You could consider testing for the minute to have passed and end, then schedule it with cron every minute, that way if it ever crashed out, it would be started again.

Not a great way, but it's an option. One wonders why you need to run it every five seconds. Can you enlighten us?

Anyway, I hope that this helps or gives you useful thoughts.

Robin
Liverpool/Blackburn
UK

3

Or:

watch -nX your_script

Where X is any number of seconds.

4

or you could just let the script sleep every 5 seconds ... start it from cron every start of the hour ... script sample below wil exit if $lockfile exists ... removing lockfile will kill running script ...

#! /bin/ksh
lockfile=/tmp/lockfile

repeatJob(){
    echo "boo"
    echo "duh\n"
    if [ ! -f $lockfile ]
    then
        break
    else
        sleep 5
        repeatJob
    fi
}

if [ ! -f $lockfile ]
then
    touch $lockfile
    repeatJob
else
    echo "$lockfile exists. Exiting."
    exit 1
fi

exit 0