\s matches newlines too, meaning that your pattern will remove empty lines, not just trim them. An alternative is 

s/^[^\S\n]+//gm;
s/[^\S\n]+$//gm;

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ihb

See perltoc if you don't know which perldoc to read!

In reply to Re^2: trim leading & trailing whitespace by ihb
in thread trim leading & trailing whitespace by ady

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