(PHP 5, PHP 7, PHP 8)
pcntl_wait — Waits on or returns the status of a forked child
&$status, int $flags = 0, array &$resource_usage = []): intThe 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.
Note:
This function is equivalent to calling pcntl_waitpid() with a
-1process_idand noflags.
status
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
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:
WNOHANG |
Return immediately if no child has exited. |
WUNTRACED |
Return for children which are stopped, and whose status has not been reported. |
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.