What about? 

$cmd = 'ps -eaf | grep -c "\< '."$0".'\>"'; 
chomp($instances = `$cmd`); 
if($instances > 1) exit;

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In reply to Re^2: Ensuring only one copy of a perl script is running at a time by Anonymous Monk
in thread Ensuring only one copy of a perl script is running at a time by eyepopslikeamosquito

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