:: Compile pcntl extension

wget //museum.php.net/php5/php-5.3.6.tar.gz
tar xvf php-5.3.6.tar.gz
cd php-5.3.6/ext/pcntl
phpize
./configure
make && make install

:: Configure pcntl extension on php.ini

vi php.ini
; add line like:
[pcntl]
extension=pcntl.so

:: Checking pcntl module

php -m | grep pcntl

:: Applying pcntl on httpd

/etc/init.d/httpd restart

:: Links
+ Google
+ StackOverFlow