Not all cron jobs are created equal, and some of them can afford to fail sporadically before we need to worry about them. Maybe they rely on a third party server, and we don’t want the occasional fail to pollute our inbox.
Here is a little cron job wrapper I created that will suppress stderr but keeps track of the job’s returned exit codes. Above a certain threshold of consecutive abnormal exits it doesn’t suppress stderr anymore.
# if the counter file doesn't already exist we create/initialize it if [ ! -f /tmp/counter_ri7g3 ] ; then echo 0 > /tmp/counter_ri7g3 ; fi ; # we pull the current counter counter=`cat /tmp/counter_ri7g3` ; # if the counter is still small, we send stderr to /dev/null if [ $counter -lt 5 ] ; then $1 > /dev/null 2>&1 ; # otherwise stderr will follow its normal path and find its way to email else $1 > /dev/null ; fi ; # lastly if running the $1 resulted in an abnormal exit, the counter is incremented if [ ! $? = 0 ] ; then counter=`cat /tmp/counter_ri7g3` ; echo "$counter+1" | bc > /tmp/counter_ri7g3 ; # and if $1 exited normally, we reset the counter else echo 0 > /tmp/counter_ri7g3 ; fi ;
a cron entry calling it looks as such:
30 * * * * root /usr/local/bin/cron_wrapper "/path/to/script arg_1 arg_2"