(PHP 3>= 3.0.10, PHP 4 , PHP 5)
posix_getsid -- Get the current sid of the process
Description
int 
posix_getsid ( int pid)
     Return the sid of the process pid. If
     pid is 0, the sid of the current process
     is returned.
    
     This is not a POSIX function, but is common on System V systems.
     If your system does not support this function at system level,
     this PHP function will always return FALSE.