Ciao,
sto seguendo
http://php.net/manual/en/ref.pcntl.php

codice:
whisher@Ugo ~ $  sudo apt-get install php5-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done
php5-dev is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 87 not upgraded.
whisher@Ugo ~ $ cd php/
whisher@Ugo ~/php $ sudo  apt-get source php5
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to find a source package for php5
sbaglio qualcosa ?