Don't do this: 
$result{$key} = 1;
$result{$key}++;

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... (In the code as written, the value can never be anything but 1.)

Sorry, that's wrong. 

$ perl -E '$key = "wrong"; $result{$key} = 1; $result{$key}++; say val
+ues %result'

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2

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The way forward always starts with a minimal test.

In reply to Re^2: find common data in multiple files by 1nickt
in thread find common data in multiple files by mao9856

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