pcntl_wait

Waits on or returns the status of a forked child.

pcntl_wait Function synopsis

pcntl_wait(
    &$status,
    int $flags = 0,
    &$resource_usage = []
  ): int

Parameters

$status

Passed by reference

pcntl_wait 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.

$flags

OptionalTypeintDefault value0

If wait3 is available on your system (mostly BSD-style systems), you can provide the optional $flags parameter. If this parameter is not provided, wait will be used for the system call. If wait3 is not available, providing a value for $flags will have no effect. The value of $flags is the value of zero or more of the following two constants OR'ed together:

$resource_usage

Passed by reference, OptionalDefault value[]

Note that the parameters $status and $resource_usage are passed by reference, and contain additional/updated context data that may be useful.

Return value

Typeint

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.