s{ \A \s+ | \s+ \z }{}xmsg;
I don't think this deserves any price for clearity.

You're using /m and /s while you aren't using any construct for which this is relevant. This just leads to more people like the OP who will think that using /m and /s is a good idea, without understanding their meaning. And then use it at the wrong time. Furthermore, I don't see the point of /g. It's just an artificial way of putting two constructs into one. The /x j u s t  m a k e s  i t  l i k e  y o u r  r e g e x p  s u f f e r s  f r o m  b a d  k e r n i n g .

I'd write it as: 

    $str =~ s/^\n+//;
    $str =~ s/\n+$//;

[download]
if only because it's idiomatic.

In reply to Re^3: Trim blanks from the beginning and end of a multi-line string by JavaFan
in thread Trim blanks from the beginning and end of a multi-line string by kenclark

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