auto remove old backup files

[xu-cheng]

remove backup files older than 30 days, but keep at least 5 copies of backup.

Fixes #102.

[xu-cheng]

Ping @bruno-

[reenberg]

I would also wary much like this to be merged in.

[Kriechi]

Does tail -n +5 work on OSX too? This usually behaves a bit different due to BSD/GNU weirdness.

[xu-cheng]

Does tail -n +5 work on OSX too?

Yes.

Updated a bit to handle when there is less 5 files. Any chance to review this and maybe merge it? Thanks.

[czchen]

Hi @bruno- ,

Any update for this PR?

[bruno-]

Is there any benefit of using pushd + popd over just ls -t $(resurrect_dir)/*.txt

[xu-cheng]

Updated to use ls -t $(resurrect_dir)/*.txt

[bruno-]

Hi,
thank you for the contribution. This is merged locally so closing this PR.

When I tested this on a mac I found the find -delete option doesn't work. The problem symptoms are described here.
To get around this I changed the delete command to use find ... | xargs rm.