pcntl_waitpid
(PHP 4 >= 4.1.0)
pcntl_waitpid -- Waits on or returns the status of a forked
child
Description
int pcntl_waitpid ( int pid, int &status, int options)
The pcntl_waitpid() function 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.
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
The value of pid can be one of the following:
Table 1. possible values for pid
< -1 wait for any child process whose process group
ID is equal to the absolute value of pid.
-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 pid.
Note: Specifying -1 as the pid is equivalent to the functionality
pcntl_wait() provides (minus options).
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:
Table 2. possible values for options
WNOHANG return immediately if no child has exited.
WUNTRACED return for children which are stopped, and whose
status has not been reported.
See also pcntl_fork(), pcntl_signal(), pcntl_wifexited(),
pcntl_wifstopped(), pcntl_wifsignaled(), pcntl_wexitstatus(),
pcntl_wtermsig() and pcntl_wstopsig().
