Robustness is in the eye of the beholder. While you don't throw away the first line if the file doesn't start with the pattern, you throw away information if the pattern appears twice in succession. And while it's given that the file starts with the pattern; it isn't given a pattern cannot appear twice. Hence your claim of "more robust" is at best dubious.

About your remark of grep {$_}, note that the result of split is an array of strings, and "0.0" is true</code>, so the grep {$_} will not filter out the 0.0.

-- Abigail