So what have you tried so far? This is a topic covered very extensively and thoroughly in nearly every Perl book I've ever seen!

Just to be helpful, try something like  $filename =~ /\.(jpg|gif|bmp)$/ for image files. I'll assume you can figure out the text file version from that. . .

- - arden.

Update: For more information, see Perl in a Nutshell Chapter 4 section 6, Programming Perl Chapter 1 section 7, Learning Perl Chapter 7 section 1, Perl Cookbook Chapter 6, or even the Tutorials here at PerlMonks!