In order to rename Images from xxxxx.gif to actualdate.gif on Linux (As long as the image have a EXIF info of course)
jhead -n%Y_%m_%d_%H_%M_%S *.jpg
This will rename files matched by *.jpg in the format YYYY_MM_DD_HH_MM_SS
(jhead is required to be installed)
I use this format so Coppermine Gallery (http://coppermine.sourceforge.net) can then change the Image description to it’s actuall date using the filename.