It looks like mlocate.db is updated on command of systemd.  

I want to have updatedb create two databases, one indexing my backup device (/srv/UpdateDevice), which is a removable filesystem containing a complete backup of (the rest of) my system, and the other indexing the complete system, including the backup device. If mlocate.db were created via a cron command this would be easy. Since actually the command comes from systemd, which I'm not familiar with, it's not so easy. Any hints?

Thanks - jon

On Mon, 2019-12-09 at 16:51 +0000, Patrick O'Callaghan wrote:
On Mon, 2019-12-09 at 08:43 -0800, Jonathan Ryshpan wrote:
I would have thought it's in /etc/cron.daily, but I can't find it. 
Where is it?

$ man locate
locate reads one or more databases prepared by updatedb(8) ...

$ man updatedb
...
updatedb is usually run daily by cron(8) to update the default database.
...

$ sudo find /etc|grep updatedb
/etc/updatedb.conf
/etc/systemd/system/timers.target.wants/mlocate-updatedb.timer