If you're retrieving all filenames using opendir and readdir (which is the way I usually do it), then you'll want to filter out at least directories (and possibly smylinks as well)
Here's one way to do it (modified from example in The Perl Cookbook):

$dir = 'path/to/directory';
opendir(DIR, $dir) or dir "Can't open $dir: $!";
while (defined($file = readdir DIR)) {
    #Test if $file is a directory
    unless (-d "$dir/$file") {
        #Test if $file is a symlink
        unless (-l "$dir/$file") {
            #push $file onto @list
            push(@list,$file);
        }
    }
}
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