This example will attempt to wait on child processes
in a situation where no child process exists,
then will print out the corresponding error message.
<?php
$pid = pcntl_wait($status);
if ($pid === -1) {
$errno = pcntl_get_last_error();
$message = pcntl_strerror($errno);
fwrite(STDERR, 'pcntl_wait failed with errno ' . $errno
. ': ' . $message . PHP_EOL);
}
The above example will output
something similar to:
pcntl_wait failed with errno 10: No child processes