(PHP 4 >= 4.1.0, PHP 5)
pcntl_waitpid — Waits on or returns the status of a forked child
$options= 0 ] )
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.
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 |
|-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 |
Specifying -1 as the
pidis equivalent to the functionality pcntl_wait() provides (minus
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().
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