Backups at alternating weeks

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#1 Thu, 02/26/2009 - 01:42
schnurzelpurz1

Backups at alternating weeks

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)?

Thu, 02/26/2009 - 05:34
andreychek

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

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 :-)
-Eric

Sat, 02/28/2009 - 00:33 (Reply to #2)
schnurzelpurz1

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.

Sat, 02/28/2009 - 06:21 (Reply to #3)
andreychek

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

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