my @entries = grep { /^\.+$/ } readdir(DH);
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Not to be too pedantic, but this code isn't particularly useful. It gives back all of the entries that consist only of dots (and, well, we know they're there!). I think you meant:

# Everything that isn't just dots.
my @e = grep { ! /^\.+$/ } readdir(DH);
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Because then your explanation matches your code. Or maybe even:

# Everything that doesn't begin with . or .. (better!)
my @e = grep { ! /^\.\.?$/ } readdir(DH);
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Because this would then eliminate "..." as a "system directory entry." (... is great for hiding things)