I  just got the script from a friends computer and added in order to use
it in my OSx. It's the original 'prename' command that comes from Debian
repositories

Usage:
perl renamer.pl 's/(\d+).*\.([\w]+)/$1.$2/' *.*
That command will replace all files named [somenumber]foo.bar to [somenumber].bar

This script was developed by Robin Barker (Robin.Barker@npl.co.uk),
from Larry Wall's original script eg/rename from the perl source.

This script is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

Larry(?)'s RCS header:
RCSfile: rename,v   Revision: 4.1   Date: 92/08/07 17:20:30 

$RCSfile: rename,v $$Revision: 1.5 $$Date: 1998/12/18 16:16:31 $

$Log: rename,v $
Revision 1.5  1998/12/18 16:16:31  rmb1
moved to perl/source
changed man documentation to POD

Revision 1.4  1997/02/27  17:19:26  rmb1
corrected usage string

Revision 1.3  1997/02/27  16:39:07  rmb1
added -v

Revision 1.2  1997/02/27  16:15:40  rmb1
*** empty log message ***

Revision 1.1  1997/02/27  15:48:51  rmb1
Initial revision