I want to create a default MAILTO for my cron jobs to use (this is a private system), without having to set MAILTO= in every file in /etc/cron.d. I had hoped I could set MAILTO in /etc/crontab (since variables like SHELL and PATH work there), but it doesn't appear to be possible. Is there a way to make all cron jobs use a default mailto address?

cron 3.0pl1-100ubuntu2 - Ubuntu Hardy

It is not only possible it also is the place to configure it. Maybe elaborate, post an example?

in /etc/crontab:
...
MAILTO=cron-alias@somewhere.com
...

in /etc/cron.d/test:
*/5 * * * * root echo "hi $MAILTO"


When the 'test' job runs, it sends an empty email to root, rather than to cron-alias. This is of course just a test to simulate any stdout from an actual cron script. If I add the MAILTO to the cron.d/test file, only then does it mail to cron-alias.

Just tested this with vixie-cron-4.1-72 adding the MAILTO and a '*/1 * * * * root /bin/env' test line to /etc/crontab. Sending e-mail to an address on another machine works (/var/log/maillog shows Sendmail sending it). There are three workarounds I can think of: catching stdin and stdout and piping that through your mailer, making a local account and having a procmail recipe forward it to the remote address, or making a local account and having an /etc/aliases entry send it off to the remote address, but those all go against your idea of configuring one mailto in a central location. You've shown (by adding your MAILTO to "/etc/cron.d/test") the generic mechanism works (so it's not a mail problem or a username lookup problem or something like that) so this could be a bug in your version. Checking your distributions bug tracker may shed a light on that.

Now that I've learned to read, I found that the cron manpage actually does shed some light on this issue:

"...Additionally, cron reads the files in /etc/cron.d: it treats the files in /etc/cron.d as in the same way as the /etc/crontab file (they follow the special format of that file, i.e. they include the user field). However, they are independent of /etc/crontab: they do not, for example, inherit environment variable settings from it."

Alas, it does not give any clues as to how to actually feed environment variables into it, nor where the variables these jobs have actually come from. Despite being run as root, the env vars do not match the root user's nor the master crontab's:

LANGUAGE=en
HOME=/root
LOGNAME=root
PATH=/usr/bin:/bin
LANG=en_US.UTF-8
SHELL=/bin/sh
PWD=/root

Since /etc/cron.d/ cronjobs submit their full commandline to '/bin/sh' you can use any form of '/bin/env MAILTO=some@addr.ess /some/command' or 'export MAILTO=some@addr.ess; /some/command' to feed envvars into it. Of course running a script instead (and sourcing MAILTO from a central resource in /etc ?) is easier on the eyes instead of finding the full commandline in your cronjob e-mail subject, and this again goes against your idea of having one central place to set the MAILTO...