topic Re: Disabling the message generation out of cronjobs in Operating System - HP-UX

Disabling the message generation out of cronjobs

sarma — Wed, 26 Oct 2005 09:50:24 GMT

HI
whenever I run a cronjob, it generates an email and sends it to inform it has been run. Is there a way to disable the notification when a cronjob runs based on some conditions

Re: Disabling the message generation out of cronjobs

Pete Randall — Wed, 26 Oct 2005 09:56:05 GMT

At the end of your cron entry, add "1>/dev/null 2>&1" (without the quotes).

Pete

Re: Disabling the message generation out of cronjobs

Alan Meyer_4 — Wed, 26 Oct 2005 09:57:22 GMT

The most common reason for email generated by cron is the handling of stdout & stderr. It's wise to redirect the output of a cron command to log files or at the very least to /dev/null as in

> /dev/null 2>&1

Re: Disabling the message generation out of cronjobs

Pete Randall — Wed, 26 Oct 2005 09:58:39 GMT

Oops, extraneous 1 in there - do it like Alan wrote it!

Pete

Re: Disabling the message generation out of cronjobs

James R. Ferguson — Wed, 26 Oct 2005 10:05:31 GMT

Hi:

Any output (STDOUT or STDERR) generated by a crontask that is not redirected to a file will be emailed to the user that submitted the job. This can be quite useful as an exception reporting mechanism, especially for STDERR when your scripts are "properly" written.

In any case, if you do not want the un-redirected output, do something like:

0 1 * * * /path/scrript > /dev/null #...discard STDOUT

0 1 * * * /path/script > /dev/null 2>&1 #...discard STDOUT + STDERR

Another way to circumvent the problem is to write your scripts to determine whether or not they have a controlling terminal. Since 'cron' jobs don't, you can begin your script with:

[ -t 0 ] || exec > /dev/null 2>&1

Regards!

...JRF...

Regards!

...JRF...

Re: Disabling the message generation out of cronjobs

Ivan Ferreira — Wed, 26 Oct 2005 10:28:24 GMT

You received a mail not because the job was run, but because the job had output and could not be displayed. That's why you need to redirect stdout and stderr in the scripts. But instead of discard the output, can be recommended to redirect the output to a logfile, if the job cannot run for some reason, you can check the log file.

Like

0 * * * * /usr/local/bin/myscript.sh > /tmp/myscript.log 2>&1

Re: Disabling the message generation out of cronjobs

Geoff Wild — Wed, 26 Oct 2005 12:08:44 GMT

Like Ivan, I tend to send output of cron to a log file - unless I don't need the info.

Examples:

0 5 * * 1 [ -d /var/adm/lp/XEBEC ] && /usr/local/bin/print.clean.receive >/dev/null 2>&1
0 6 21 * * [ -d /var/adm/lp/XEBEC ] && /usr/local/bin/lpqpurge >/tmp/lpqpurge.cronlog 2>&1

Rgds...Geoff

Re: Disabling the message generation out of cronjobs

sarma — Wed, 26 Oct 2005 13:58:05 GMT

thank you for the information