pcntl_waitpid
(PHP 4 >= 4.1.0, PHP 5, PHP 7)
pcntl_waitpid — Waits on or returns the status of a forked child
Description
pcntl_waitpid ( int $pid , int &$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.
Parameters
-
pid -
The value of
pidcan be one of the following:possible values for pid< -1wait for any child process whose process group ID is equal to the absolute value of pid.-1wait for any child process; this is the same behaviour that the wait function exhibits. 0wait for any child process whose process group ID is equal to that of the calling process. > 0wait for the child whose process ID is equal to the value of pid.Note:
Specifying
-1as thepidis equivalent to the functionality pcntl_wait() provides (minusoptions). -
status -
pcntl_waitpid() will store status information in the
statusparameter 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
optionsis the value of zero or more of the following two global constantsOR'ed together:possible values for optionsWNOHANGreturn immediately if no child has exited. WUNTRACEDreturn for children which are stopped, and whose status has not been reported.
Return Values
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
See Also
- pcntl_fork() - Forks the currently running process
- pcntl_signal() - Installs a signal handler
- pcntl_wifexited() - Checks if status code represents a normal exit
- pcntl_wifstopped() - Checks whether the child process is currently stopped
- pcntl_wifsignaled() - Checks whether the status code represents a termination due to a signal
- pcntl_wexitstatus() - Returns the return code of a terminated child
- pcntl_wtermsig() - Returns the signal which caused the child to terminate
- pcntl_wstopsig() - Returns the signal which caused the child to stop
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https://www.php.net/manual/en/function.pcntl-waitpid.php