$_ = "   no  \n   \n   \n    they    \n \n    won't     \n\n\n";
s/^\s*(.*?)\s*$/$1/gm;
print;

[download]
Result: 
no
they
won't

All blank lines are gone.

In reply to Re^3: trim leading & trailing whitespace by bart
in thread trim leading & trailing whitespace by ady

Title:
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