s/#.*$//;
next if /^$/;
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That'll probably bite you eventually. Consider these lines from an imaginary configuration file:

# Set the format for currency: 
currency_format = '$###.##';
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Skipping comment-only lines right off the bat is an optimization. Other lines will probably require smarter parsing.

Even if the file format guaranteed that your method could be used safely, I wouldn't use it. Why do an expensive substitution on lines you are going to throw out? I'd do it like this:

next if /^\s*#/; 
s/#.*$//;
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We've probably strayed quite a bit from the OP's needs though.

-sauoq
"My two cents aren't worth a dime.";