subject: Then go into the extension directory [print this page] By default pcntl library is not enabled on web server installation. In order to use pcntl_fork() function you need to compile and enable pcntl.so module. That is pretty easy on Ubuntu.
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Firstly install the php5-dev package:
apt-get install php5-dev
Create a temporary folder and get php sources
mkdir php
cd php
apt-get source php5
Then go into the extension directory.
cd php5-5.1.2/ext/pcntl
Compile the extension
phpize
./configure
make
Copy the extension
cp modules/* /usr/lib/php5/20051025/
Your php5 library directory might be named something else.
