[Nottingham] e-mail from a shell...

[Graeme Fowler]

On Wed, 21 Apr 2004, David Wolfson wrote:
> I've not had time to try the VPN yet, but have been trying to tidy up some
> other loose ends first.  I've been sorting out some cron configurations, and
> am confused by the "MAILTO= " command.

Erm...

If, and only if, the cron jobs create any output on either stderr or stdout, 
will crond email the address given in the MAILTO environment variable (not a 
command).

For example, a cronjob like so:
MAILTO=user at domain.name
5 * * * * ls -lart /tmp/

Should spit out an email of the form:

-- cut here --
From: cronuser at server
To: <user at domain.name>
Subject: Cron <user at server> ls -lart /tmp/

-r--r--r--    1 root     root           11 Apr 21 08:03 .X0-lock
drwx------    2 graeme   graeme     147456 Apr 21 08:03 orbit-graeme

-- cut here --

And that would be it.

The 'mail' command is a very basic mail application. invoking 'mail' on its' 
own gives you a command-line driven, basic mail reader. Doing something like:

echo "hello" | mail -s "mail test" user at server.domain.name

will email user at server.domain.name a message of subject "mail test", body a 
single line "hello".

> I've also tried using the 'mail to' command in a shell, appears to work but
> never arrives.

That's because you're trying to send an email to a local user named "to". 
Assuming you don't have one, your local mail spool should contain a bounce 
message.

  I'm guessing that I have to configure this command, but when
> I try and to a google/linux-questions search I get a huge list of peoples
> e-mail links.  Not very helpful.

"man mail" is your friend :) as, in this case, is "man 5 crontab"...

> Am I barking in the wrong woods?  Is it possible to send e-mail in the form
> I want from a shell script?  If so, could anyone point me in the right
> direction?  I'd like to be able to find out from my inbox if my cron jobs
> have run ok...

If they exit silently when they've completed with no errors, expect no emails 
from cron :)
If you make them output a "job blah ran successfully" as the last part, you'll 
get some output and therefore an email.

Of course, this is assuming that you have a sendmail (or exim, or similar) 
binary for messages to be sent with. And that your box can do DNS lookups if 
they're needed for remote mail!

HTH

Graeme