get the timestamp as a log filename

[Bevan C. Bennett]

> which does not produce a file name that sorts the way I like.
> I would use something like...
> 
>   $ date +"%Y-%m-%d_%R"
>   2004-01-23_09:01

That's highly recommended, although %Y-%m-%d generally suffices, since 
logrotate won't run more than once per day unless forced.

Dropping something like the following in the appropriate section of 
logrotates.conf or logrotate.d appears to work splendidly, if you want 
to keep these logs indefinately. You may also want to use 'rotate 0'.

I used /etc/logrotate.d/rpm for testing:

postrotate
    /bin/cp /var/log/rpmpkgs.1 /var/log/rpmpkgs-`/bin/date +"%Y-%m-%d-%R"`
endscript