I had Cron running my recollindex job at the desired time and I had sSmtp set up to email using POP through my gmail email account. The trouble was recollindex gives a lot of output and I was being sent an email with over 22,000 lines in it each time Cron ran the job!
I checked to see if there were command line options I could pass to recollindex to make it run silently or at least more quietly. No joy – recollindex doesn’t support that type of functionality.
I could make it silent by adding a redirect to null on the crontab command line like:
15 01 * * * recollindex >/dev/null 2>&1
But that would mean there would never be any output and there’d never be an email – whether recollindex ran successfully or otherwise.
I Googled a bit and found Chronic. This is a wrapper for Cron jobs. Chronic manages the output from other programs and arranges to only display that output if the command has an error or fails. If the command succeeds, any other output will be hidden. And that means no email. So you only get an email if it doesn’t work. Perfect.
To install Chronic type the following into a terminal:
sudo apt-get install moreutils
And to use it in the crontab listing, precede the command you wish to run with chronic, like this:
15 01 * * * chronic recollindex
And to test? Set the time just a few minutes into the future and let it run. You can use top to watch the process list and see that the processes are launched. If it all works according to plan you shouldn’t get an email.
I then changed the command line again so that it would generate an error. I added an extra x to the recollindex command. Because it was spelled incorrectly Cron wouldn’t be able to find a program by that name and that would generate an error. And because there had been an error I should get an email. So I used crontab and changed the line to say:
15 01 * * * chronic recollindexx
Note the extra x. I set the time to a few minutes in the future, let the job run and then checked my email. I had an email with the following subject:
Cron <dave@Nostromo> chronic recollindexx (failed)
and the following content:
Command ‘recollindexx’ not found in /usr/bin, /bin at /usr/bin/chronic line 44
Finally – success! Cron warns me by email if recollindex fails, and only if it fails. (The last step was to go back into crontab and remove the extra x and reset the time to my desired time of 01:15.)
So. I had Recoll working fine and Cron launching recollindex every night at 01:15 to update the index. I wanted to have Cron email me to let me know that recollindex had been launched successfully each night. That was easily achieved by adding the following line to the crontab file:
I substituted my real email address for the dummy values shown here of course. That told Cron I wanted it to email me. But for Ubuntu to be able to email out it either needs to be set up as an email server or it needs to be able to authenticate against an existing external email server (like Thunderbird does). I didn’t want to have to configure an email server on my Ubuntu PC just for this, so I hunted round for ways to have it authenticate against an external mail server.
Happily, I found sSmtp. sSmtp is an extremely simple, resource conserving, SMTP server that will allow your PC to do just that. It allows processes in your PC to email out, by authenticating against an external mail server. One of my email accounts is a Google mail (gmail) account. I chose to use the gmail mail server as my external mail server.
To install sSmtp type the following into a terminal window:
sudo apt-get install ssmtp
When it had installed I used gedit to edit the ssmtp.conf file.
I added or edited the following lines:
Of course I used my real gmail email adddress details, username and password.
Then I added each account that I wanted to be able to send mail from by editing the revaliases file.
I added two lines, one for root and one for me.
Again, I used my real gmail email address and my Ubuntu local username.
Now all I had to do was configure gmail to accept POP.
Once I had done that I could test the email throughput by sending an email to one of my other accounts using the following terminal command:
sudo ssmtp email@example.com
Use a real, but different email address than your gmail one.
The message must be formatted in the following way:
Subject: Example Message
and then hit Ctrl-D. Note the blank line following the Subject: to line. Everything after that is the body of the email. Then go and check your other email account and see if the email got there. If there are any immediate issues, you will see an error message in the terminal window.
If everything has gone according to plan, you should receive the email. It all worked, and that meant that Cron would be able to email me when the recollindex program was launched each night. And that is what happened. In the wee wee hours of the morning I got an email from Cron. All 22,000 lines of it! The output from recollindex is verbose, to understate the matter somewhat.
And that’s what brought me to Chronic.