That may work, but that regex hurts my head. The only way I would use that code is if it were commented well as to what each part of the regex does - even then I might not use it.

A much clearer, albeit more code and more steps method, would be to:

  1. read from the input file, and
  2. write only lines that you want to write
     to a temporary output file, and
  3. close the input file
  4. rename the temporary output file to the input file's
     name.
[download]

This method would allow you to read ahead one (or more than one) line to see if there are 2 more more blank lines together.

Just my preference, but IMHO much clearer than trying to decifer that regex. My choice is to always make my code as understandable to *everyone* (including newbies) as possible. Obfuscated regex's do more to scare people away from Perl. Just my 2c.

HTH.