(PHP 5 >= 5.3.4, PHP 7, PHP 8)
pcntl_strerror — Retrieve the system error message associated with the given errno
   Returns the system error message associated with the given error_code
   (errno) of the last pcntl function that failed.
   The error_code parameter may be obtained by calling
   pcntl_get_last_error().
  
error_code
      An error number (errno),
      returned by pcntl_get_last_error().
     
Returns the error message, as a string.
示例 #1 pcntl_strerror() example
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);
}以上示例的输出类似于:
pcntl_wait failed with errno 10: No child processes
