Python subprocess.call 和 subprocess.Popen 给我不同的输出

Question

使用 subprocess.call 时，输出符合预期。

result = subprocess.call([securefx, '/NoPrompt', '/Q', '/RetryCount', retries, 
              '/RetryDelay', '1', '/Log', sfxLogFile, '/List', '/S', session])

打印结果会输出类似 -533428 或 0

但是当我运行的时候

args = [securefx, '/NoPrompt', '/Q', '/RetryCount', retries, '/RetryDelay', '1', 
       '/Log', sfxLogFile, '/List', '/S', session]
process = subprocess.Popen(args, stdout=subprocess.PIPE)
result = process.communicate()[0]

并打印结果，我得到空白或 stderr = "None"。

为什么不同？即使通话正常，我仍在尝试 Popen 的原因是:Python subprocess.call on sfxcl.exe not working from Windows 2003 Task Scheduler <- 我想我会试一试...

Answer 1

subprocess.Popen 返回 Popen object ，您可以使用它与进程通信并获取输出，但是 subprocess.call 只会返回进程的返回码:

subprocess.call(*popenargs, **kwargs)
  Run command with arguments. Wait for command to complete, then return the returncode attribute.

So subprocess.call is basically equivalent to the following code, and only exists for convenience:

def call(*popenargs, **kwargs):
    p = subprocess.Popen(*popenargs, **kwargs)
    return p.wait()