(PHP 4 >= 4.1.0, PHP 5, PHP 7)
pcntl_waitpid — Waits on or returns the status of a forked child
$pid
, int &$status
[, int $options = 0
[, array &$rusage
]] ) : int
Suspends execution of the current process until a child as specified by
the pid argument has exited, or until a signal is
delivered whose action is to terminate the current process or to call a
signal handling function.
If a child as requested by pid has already exited
by the time of the call (a so-called "zombie" process), the function
returns immediately. Any system resources used by the child are freed.
Please see your system's waitpid(2) man page for specific details as to
how waitpid works on your system.
pid
The value of pid can be one of the following:
| < -1 |
wait for any child process whose process group ID is equal to
the absolute value of pid.
|
| -1 | wait for any child process; this is the same behaviour that the wait function exhibits. |
| 0 | wait for any child process whose process group ID is equal to that of the calling process. |
| > 0 |
wait for the child whose process ID is equal to the value of
pid.
|
Note:
Specifying -1 as the
pidis equivalent to the functionality pcntl_wait() provides (minusoptions).
status
pcntl_waitpid() will store status information
in the status parameter which can be
evaluated using the following functions:
pcntl_wifexited(),
pcntl_wifstopped(),
pcntl_wifsignaled(),
pcntl_wexitstatus(),
pcntl_wtermsig() and
pcntl_wstopsig().
options
The value of options is the value of zero
or more of the following two global constants
OR'ed together:
| WNOHANG | return immediately if no child has exited. |
| WUNTRACED | return for children which are stopped, and whose status has not been reported. |
pcntl_waitpid() returns the process ID of the
child which exited, -1 on error or zero if WNOHANG was used and no
child was available