Backups at alternating weeks

General Discussion
1

Hi there

I want to setup the following backup strategy:

  • every day of the week an incremental backup (easy to setup)
  • two alternating full backups at the end of the week. In case a full backup fails, I still got the one of the previous week (including the daily ones).
    The problem is, that the days within the month will change. Is there a trick to let virtualmin do the job (e.g. manually edit cronjobs)?
2

Yeah, running a cron job every other weekend is tricky :slight_smile:

It would probably be simplest to manually edit the cron file to add in the appropriate cron schedule – so setup your backup schedule just for weekly or whatever, edit /var/spool/cron/crontab/root, and change it to use something like this:

00 02 1-7,15-21 * Sat /etc/webmin/virtual-server/backup.pl …

The above says to run Virtualmin’s backup.pl at 2:00am on Saturday, when the day of the month is 1-7, and then again when it’s 15-21.

It’s not entirely pretty, but that will essentially run every other week on the weekend :slight_smile:
-Eric

3

Hi Eric
Thanks for your solution. But what about the days 28-31?
After some googleing I came up with the following solution:[ul]
[li]Setting up two jobs that run every week[/li][li]In the field “Command to run before backup” I put the expression [[ $(expr date +%W % 2) = 0 ]] (returns 1 for even weeks)[/li][li]In the field of the 2nd job the expression is evaluated against 1 (instead of 0)[/li]
[/ul]This way there’s no need to poke around in files that may be overwritten by Virtualmin. Haven’t tested it yet but hope that it works.

4

Yeah, mine was kind of hacky. Nice find you have there, thanks for posting it!
-Eric