PHP 即使在 Windows 后台执行运行命令后，脚本仍卡在 exec 上

Question

我想要一个 php 脚本，我可以从中执行程序，如果它没有在 2 秒内完成执行则终止它。我正在使用 Windows。我试过以下代码：

exec("start /B program.exe");
sleep(2);
exec('taskkill /F /IM "program.exe"');

这似乎不起作用，因为只要 program.exe 未完成执行，脚本就会卡在第一个 exec 语句上。我不知道如何解决这个问题。

Answer 1

对，exec()会阻塞直到执行完成。 This question has great answers for how to do an exec() with a timeout. I think this 可能最适合您。为了完整起见，我将 post 此处的代码（但我不能接受任何信用！）：

/**
 * Execute a command and return it's output. Either wait until the command exits or the timeout has expired.
 *
 * @param string $cmd     Command to execute.
 * @param number $timeout Timeout in seconds.
 * @return string Output of the command.
 * @throws \Exception
 */
function exec_timeout($cmd, $timeout) {
  // File descriptors passed to the process.
  $descriptors = array(
    0 => array('pipe', 'r'),  // stdin
    1 => array('pipe', 'w'),  // stdout
    2 => array('pipe', 'w')   // stderr
  );

  // Start the process.
  $process = proc_open('exec ' . $cmd, $descriptors, $pipes);

  if (!is_resource($process)) {
    throw new \Exception('Could not execute process');
  }

  // Set the stdout stream to none-blocking.
  stream_set_blocking($pipes[1], 0);

  // Turn the timeout into microseconds.
  $timeout = $timeout * 1000000;

  // Output buffer.
  $buffer = '';

  // While we have time to wait.
  while ($timeout > 0) {
    $start = microtime(true);

    // Wait until we have output or the timer expired.
    $read  = array($pipes[1]);
    $other = array();
    stream_select($read, $other, $other, 0, $timeout);

    // Get the status of the process.
    // Do this before we read from the stream,
    // this way we can't lose the last bit of output if the process dies between these     functions.
    $status = proc_get_status($process);

    // Read the contents from the buffer.
    // This function will always return immediately as the stream is none-blocking.
    $buffer .= stream_get_contents($pipes[1]);

    if (!$status['running']) {
      // Break from this loop if the process exited before the timeout.
      break;
    }

    // Subtract the number of microseconds that we waited.
    $timeout -= (microtime(true) - $start) * 1000000;
  }

  // Check if there were any errors.
  $errors = stream_get_contents($pipes[2]);

  if (!empty($errors)) {
    throw new \Exception($errors);
  }

  // Kill the process in case the timeout expired and it's still running.
  // If the process already exited this won't do anything.
  proc_terminate($process, 9);

  // Close all streams.
  fclose($pipes[0]);
  fclose($pipes[1]);
  fclose($pipes[2]);

  proc_close($process);

  return $buffer;
}

编辑

proc_open() 的 'exec' 部分可能不适用于 Windows，但可能没有必要。

Answer 2

exec() 手册页的 first comment 显示了一个非常简单的示例。

Answer 3

你是用 php cli (command line)? Open a command prompt as administrator 来做的吗？
为了不被等待程序close the process of opening the program.

阻塞

php myscript.php

pclose(popen("start /B program.exe", "r"));
sleep(2);
exec('taskkill /F /IM program.exe');
exit(0);

也可以将 exec start 放入单独的脚本中并使用 exec

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