Someone

#!/usr/bin/perl
#!/usr/local/bin/perl

use strict;
do_dir('/tmp');
exit;

sub do_dir {
	my $mysymlink;
    my $dir = shift;
    opendir(D, $dir);
    my @f = readdir(D);
    closedir(D);
    foreach my $file (@f) {
        my $filename = $dir . '/' . $file;
        if ($file eq '.' || $file eq '..') {
        } elsif (-d $filename) {
            # depending on your needs you can do subdirs
            do_dir($filename); 
        } else {
            # do something with $filename, like ...
            if(substr($filename, length($filename)-4,4) eq ".jpg")
            {
            $mysymlink = "ln -s " . $filename . "  _thb_" . $filename;
            print "$mysymlink\n";}
        } 
    }
}