--link-dest but only if rsync detects differences

[lewis butler]

On 13-Nov-2008, at 14:17, Daniel Jarboe wrote:
> I'm currently using rsync and --link-dest to give me something like a
> poor-man's incremental snapshot to disk.  But I really only want to  
> generate
> a new backup if rsync detects differences, otherwise I don't need a  
> new
> backup.


But with link-dest you are not creating a new backup; you are only  
creating new LINKS to the same backup.

If the new backup has no changes from the last backup, it takes up no  
space, so why does it matter?  You simply expire your old backup off  
automatically with a rotate script.

Here's what my backup folder looks like:

   2 drwxr-xr-x  23 root  wheel       1024 Nov 14 00:54 serv1.daily.0
   2 drwxr-xr-x  23 root  wheel       1024 Nov 13 01:05 serv1.daily.1
   2 drwxr-xr-x  23 root  wheel       1024 Nov 12 00:57 serv1.daily.2
   2 drwxr-xr-x  23 root  wheel       1024 Nov 11 00:58 serv1.daily.3
   2 drwxr-xr-x  23 root  wheel       1024 Nov 10 00:58 serv1.daily.4
   2 drwxr-xr-x  23 root  wheel       1024 Nov  9 00:55 serv1.daily.5
   2 drwxr-xr-x  23 root  wheel       1024 Nov  8 00:56 serv1.daily.6
   2 drwxr-xr-x  24 root  wheel       1024 Oct  1 00:21 serv1.monthly.0
   2 drwxr-xr-x  24 root  wheel       1024 Sep  1 00:22 serv1.monthly.1
   2 drwxr-xr-x  24 root  wheel       1024 Aug  1 00:22 serv1.monthly.2
   2 drwxr-xr-x  24 root  wheel       1024 Jul  1 00:21 serv1.monthly.3
   2 drwxr-xr-x  24 root  wheel       1024 Jun  1 00:22 serv1.monthly.4
   2 drwxr-xr-x  24 root  wheel       1024 May  1 00:27 serv1.monthly.5
   2 drwxr-xr-x  23 root  wheel       1024 Nov 15 00:52 serv1.sday.0
   2 drwxr-xr-x  23 root  wheel       1024 Nov 14 18:55 serv1.sday.1
   2 drwxr-xr-x  23 root  wheel       1024 Nov 14 12:58 serv1.sday.2
   2 drwxr-xr-x  23 root  wheel       1024 Nov 14 06:53 serv1.sday.3
   2 drwxr-xr-x  23 root  wheel       1024 Nov  1 00:51 serv1.weekly.0
   2 drwxr-xr-x  23 root  wheel       1024 Oct 25 00:51 serv1.weekly.1
   2 drwxr-xr-x  23 root  wheel       1024 Oct 18 00:52 serv1.weekly.2
   2 drwxr-xr-x  23 root  wheel       1024 Oct 11 00:48 serv1.weekly.3

sday.3 becomes daily.0 and daily.6 becomes weekly.0 and weekly.3  
becomes monthly.0

-- 
Please to meet you, Rose.  Now run for your life!