PCNTL in PHP allows for some handy advanced “trickery” using the OS process functions inherent in Linux (*nix?). I believe some features are available in Windows, but I know for certain that pcntl_fork() is not.
Anyway, it is not enabled by default, so if you want to take advantage of the functions on your Ubuntu LAMP server, you might spend hours searching the web for that magic aptitude command. But, as far as I can tell, it doesn’t exist.
Luckily, I stumbled across this article on the Ubuntu forums, so I’m dedicating a post here with the hopes that other will find it more easily.
Please note that you’ll probably need build-essentials and a few other source compilation basics, but as long as you have that, the following code will get you what you want.
First, in your home directory:
mkdir php cd php apt-get source php5 cd php5-(WHATEVER_RELEASE)/ext/pcntl phpize ./configure make
cp modules/pcntl.so /usr/lib/php5/WHEVER_YOUR_SO_FILES_ARE/ echo "extension=pcntl.so" > /etc/php5/conf.d/pcntl.ini
FYI: “make install” does not appear to put the files in the correct place.