You wrote:

perl -na0777e '%a = map {$_, ++$a{$_}} @F; print join("\n", (sort { $a
+{$b} <=> $a{$a} } keys %a)[0..9]), "\n"' <filename>
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I don't like the %a = there. You're creating the hash inside the map, but then overwriting it with the values again. Messy messy. I'd stick with something like:

perl -ne '$a{$_}++ for split; END { @a = sort { $a{$b} <=> $a{$a} } ke
+ys %a; print "$_\n" for @a[0..9]; }' <filename>
[download]

-- Randal L. Schwartz, Perl hacker