I should have mentioned in my previous blog post that my friend Jonathan originally told me about perl -00pe0. After I posted it, we exchanged a few more emails about various ways to squeeze multiple blank lines, and he pointed out that cat -s is not, in fact, exactly the same as perl -00pe0. The difference is how they deal with leading blank lines. cat -s will squeeze them down to a single blank line, but perl -00pe0 will remove all of the leading blank lines.