Description:
------------
There is a mistake here(http://www.php.net/manual/en/ref.pcntl.php) on invoking  posix_setsid(),which is return -1 on errors.

Reproduce code:
---------------
if (!posix_setsid()) {
    die("could not detach from terminal");
}

Expected result:
----------------
When a error occurs,the msg"could not detach from terminal" should be printed.But since the posix_setsid() return -1 on errors,nothing is printed in this case.

Actual result:
--------------
nothing is printed