Thanks for the answer!
The problem with selection is, I think, I can't use regex.
If I understood right, you don't have to rename the matching files
immediately, you can first test the result, which would be enough for me, since
I don't really want to rename the files...
Said in unix words, I like to use "ls" with a wildcard for all files in a path
and pipe the result with "egrep" using a regex.
Or is there another tool?