I have a process which is started by Сron like this:
timeout 1h /app/longprocess.sh
Now I want to be notified by email if something goes wrong with it. Imagine this:
notifyme maintainer@example.org timeout 1h /app/longprocess.sh
where notifyme is a supposed command which will send an email to maintainer@example.org with the output of the command in case the command exits with a non-zero status. Is there something like this?
cron already sends mails, if a compatible /usr/sbin/sendmail is installed (e.g. msmtp, ssmtp, Postfix, OpenSMTPD…). See also: What is the "You have new mail" message in Linux/UNIX?
chronic from moreutils can handle the "only on success" part:
chronic timeout 1h /app/longprocess.sh
sometask||echo Something Went Wrong! | mail -s E-MailSubject user@example.com
The || will only run what is on the right, if the command on the left returns a non-zero error code. This functionality is built into the shell (I'm seeing this question has the "bash" tag), so no extra external program is needed to support that functionality. The "mail" program is quite commonly pre-installed on many operating systems.
Similarly, you could do:
sometask&&echo Something Went Right! | mail -s E-MailSubject user@example.com
which would only run what happened on the right if things were successful. (By "successful", I specifically mean that "zero" is the return code from the command specified on the left.)
Edits: I initially wrote this late at night and, unfortunately, an update was required for accuracy, which is why comments pointed out some aspects of the answer. (Thanks MariusMatutiae and grawity!) I decided that, in the long term, fixing the answer is better than leaving it in a state that is more prone to cause confusion.
You can always use the following method by adding:
MAILTO=xyz@example.com
in your cron and you will be inform. I have tried this and it worked for me all the time.
