PCRE is the Perl Compatible Regular Expressions library. It is used by a number of large Open Source projects including Python, Apache, Postfix, KDE, Analog, and PHP. Philip Hazel developed PCRE, it can be downloaded from http://www.pcre.org/. To install PCRE, type the following: tar xvzf pcre-3.9.tar.gz cd pcre-3.9 ./configure make make install