PHP: What does pcntl_fork() really do?

Question

PHP\'s pcntl_fork function is supposed to fork a process just as the standard fork function in C.
But I was wondering if this function really forks the process or if it

Answer 1

I have just tried to use pcntl_fork via apache, the strange situation is that after fork a child process, the parent give the standard output(browser) to its child. So, you can image, the browser cann't receive the output from the parent process.