無法在Python中按名稱獲取進程的PID

Question

我有一段非常簡單的代碼

import subprocess
print(subprocess.check_output(["pidof","ffmpeg"]))

它將打印名為ffmpeg的進程的PID（請參閱此處 ）。 但是，我總是收到以下錯誤：

subprocess.CalledProcessError: Command '['pidof', 'ffmpeg']' returned non-zero exit status 1

適用於python2和python3。 我究竟做錯了什么？

Answer 1

來自man pidof ：

EXIT STATUS
       0      At least one program was found with the requested name.

       1      No program was found with the requested name.

您只是沒有任何名為ffmpeg進程。

Answer 2

您可以使用try來避免執行被阻塞

用這個

import subprocess

try:

    print(subprocess.check_output(["pidof","ffmpeg"]))
except subprocess.CalledProcessError:
    print("no process named ffmpeg")

您會收到錯誤消息，因為如果pidof ffmpeg沒有給出任何輸出，並且使用print(subprocess.check_output(["pidof","ffmpeg"]))我們期望該命令輸出。

你也可以用

print(subprocess.getoutput("pidof ffmpeg"))

即使該命令的輸出為none ，也不會出錯

如果您檢查庫方法check_output ，則可以找到此方法

def check_output(*popenargs, timeout=None, **kwargs):
    r"""Run command with arguments and return its output.

    If the exit code was non-zero it raises a CalledProcessError.  The
    CalledProcessError object will have the return code in the returncode
    attribute and output in the output attribute.

    The arguments are the same as for the Popen constructor.... """