Likely opendir didn't open directory for some reason. Add error reporting to find why:

opendir(DIR,"/some_dir") or die "Cannot open directory: $!";
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Update: Actually your usage of readdir and <> operator is incorrect. readdir accepts only one argument - directory handle and <> can read only from file handles. Correct code should look like:

#!/usr/bin/perl -w
use strict;

opendir DIR, '/some_dir' or die "Cannot open directory: $!";
my @files = grep !/^.$/, readdir DIR;
closedir DIR;
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Ilya Martynov, ilya@iponweb.net
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