Cron Question

[Derek Ragona]

At 10:45 AM 9/2/2008, ElihuJ wrote:

>Hi all. I have a question about cron jobs that seem to be running to long or
>with multiple copies of itself. For example, I have a backup script that I
>run that seems to make multiple copies of itself. If I view the running
>processes I see numerous instances of the same cron job. Is there something
>I can do to limit this from happening? When it does, it drains my CPU and
>some of my other processes are non responsive. Any help would be
>appreciated. Thank you.
>--
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For longer running jobs I do a couple things.  I use a file to be sure only 
one instance is running, but I also add signal handling.  The following is 
written for ksh, but can be adapted to sh if needed:

=============================================================
#!/usr/local/bin/ksh
# uncomment the following line for debugging
#set -x


RUNNING_FILE=RUNNING_FILE=/tmp/my_cronjob_running
LOGFILE=LOGFILE=/tmp/my_cronjob.log
SENDTO=me at mydomain.com
MAIL=/usr/bin/mail
TOUCH=/usr/bin/touch
RM=/bin/rm


# Print an epilog string and clear the RUNNING_FILE
function epilog {
   echo "We are all done scanning." >> $LOGFILE
         $MAIL -s "MyCronjob Report" $SENDTO < $LOGFILE
         if [ -f $RUNNING_FILE ]; then
                 $RM $RUNNING_FILE;
         fi
}

function got_signal {
   echo "Got a signal" >> $LOGFILE
   epilog
   exit
}


# Here pointers to signal handling subroutines are set
trap got_signal TERM HUP INT QUIT

if [ -f $RUNNING_FILE ]; then
         echo "mycronjob is already running"
else
         $TOUCH $RUNNING_FILE
         $RM $LOGFILE
         $TOUCH $LOGFILE
#       add your job to be done here . . .
#
         epilog
fi

=============================================================

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