[SOLVED] Crontab

GioBonvi · 10-18-2015, 02:40 AM

Hello everyone!
In the last few months I've been working on a little server for home purposes (VPN, little site-project to be used in LAN, network boot PXE server and some other things).
My main objective is to learn something new, rather than build something really useful.

Yesterday I installed ssmtp on my server and configured it to use my secondary gmail address (let's say second@gmail.com)
Everything went really fine and I was able to send an email by doing:

Code:

ssmtp first@gmail.com
First line
Second line
^Q

or

Code:

echo "First line
second line" | ssmtp first@gmail.com

The problem raised when I tried to put such a job in crontab.
I did

Code:

crontab -e

and added this line to crontab:

Code:

*/10 * * * * /home/user/test.sh

Where test.sh was an executable file:

Code:

#!/bin/bash
echo "FIRST TRY First line
second line" | ssmtp first@gmail.com
echo "SECOND TRY First line" | ssmtp first@gmail.com

But nothing happened... I tested crontab by replacing "/home/user/test.sh" with "echo 1 > /home/user/list" and it worked. Then I tried to put "sh /home/user/test.sh" but there was no difference.
Finally I tried executing manually the script and IT SENT THE MAIL!

I don't know what to do...

berndbausch · 10-18-2015, 05:48 AM

I don't know ssmtp, but perhaps it expects certain environment variables which are not set in cron's environment. Find out if that is the case and set those variables in the script.

Futhermore, if you don't redirect stout and stderr to a file, cron will send you ssmtp's messages via email. So check your email, and modify the script to redirect IO to a file.

GioBonvi · 10-18-2015, 11:07 AM

Quote:

Originally Posted by berndbausch

I don't know ssmtp, but perhaps it expects certain environment variables which are not set in cron's environment. Find out if that is the case and set those variables in the script.

Futhermore, if you don't redirect stout and stderr to a file, cron will send you ssmtp's messages via email. So check your email, and modify the script to redirect IO to a file.

Thank you, berndbausch!

You were right! I googled for "ssmtp and cron" (which I hadn't thought of) and immediately found this:
http://askubuntu.com/questions/382049/crontab-and-ssmtp

It seems that in the cron environment you need to specify the full ssmtp path (/usr/sbin/ssmtp) instead of only ssmtp

Not sure if this is a bug or if there is a definitive solution instead of this "workaround", but I'm definetely OK with this solution.

Thank you again. Problem solved!

chrism01 · 10-18-2015, 09:18 PM

By default, cron's env is deliberately minimal (security etc), so this is a common gotcha for anything run inside cron.
Best to either provide full paths to cmds and files or write a script and call that from cron (more robust & private) and have the script set whatever it needs for that job.