1 May
2005
1 May
'05
5:06 p.m.
I don't think the extension directive runs shell commands. You can do something like this with the lastaction script which I got from Debian lists (http://lists.debian.org/debian-user/2004/08/msg04714.html)
lastaction DATE=`date +%F`; mv /var/log/messages.1.gz /var/log/messages-$DATE.gz endscript
Modify to suit your needs.