Shell Programming and Scripting

DIFF=`comm -13 /var/spool/cron/crontabs/jun /var/tmp/temp_crontabs/jun_temp`
#DIFF=`comm -13 /var/tmp/temp_crontabs/jun_temp /var/spool/cron/crontabs/jun`

if [ "$DIFF" == "" ]
then

echo "======================"
echo "No change in crontab"
echo "======================"

else

echo "$DIFF"
echo "$DIFF"|mailx -s "Crontab Change Alert" my-email@id.com
fi


cp /var/spool/cron/crontabs/jun /var/tmp/temp_crontabs/jun_temp

bash-3.2$ cat c1
* * * * * cmd 1
* * * * * cmd 2
* * * * * cmd 3
bash-3.2$ cat c2
* * * * * cmd 4
* * * * * cmd 5
* * * * * cmd 6
* * * * * cmd 1
bash-3.2$ 
bash-3.2$ bash c.sh
* * * * * cmd 4
* * * * * cmd 5
* * * * * cmd 6
bash-3.2$ 
bash-3.2$ 
bash-3.2$ cat c.sh
#!/bin/bash
DIFF=$(comm <(sort c1) <(sort c2) | awk -F "\t" 'length($2)>0{print $2}' )
if [ "${DIFF}" != "" ]
then
        IFS=$"\n";
        echo ${DIFF}
fi