pcntl_wait
(PHP 5, PHP 7, PHP 8)
Waits on or returns the status of a forked child
Description
The wait function suspends execution of the current process until a child 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 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 wait(2) man page for specific details as to how wait works on your system.
This function is equivalent to calling pcntl_waitpid() with a -1 process_id and no flags.
Parameters
statuspcntl_wait()will store status information in thestatusparameter which can be evaluated using the following functions:pcntl_wifexited(),pcntl_wifstopped(),pcntl_wifsignaled(),pcntl_wexitstatus(),pcntl_wtermsig()andpcntl_wstopsig().flagsIf wait3 is available on your system (mostly BSD-style systems), you can provide the optional
flagsparameter. If this parameter is not provided, wait will be used for the system call. If wait3 is not available, providing a value forflagswill have no effect. The value offlagsis the value of zero or more of the following two constantsOR'ed together:WNOHANGReturn immediately if no child has exited. WUNTRACEDReturn for children which are stopped, and whose status has not been reported. resource_usageThe
resource_usageparameter is set to an associativearraycontaining resource usage statistics from the child process. For information on the contents seegetrusage().This is only supported if the
wait3(2)system call is available on the system; otherwise the parameter is left untouched. If no child process was reaped, that is if the function returns0or-1, the parameter is set to an emptyarray.
Return Values
pcntl_wait() returns the process ID of the child which exited, -1 on error or zero if WNOHANG was provided as an option (on wait3-available systems) and no child was available.