如何从 Python 中的子进程获取返回码和输出？
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How to get both return code and output from subprocess in Python?
提问by Viktor Malyi
While developing python wrapper library for Android Debug Bridge (ADB), I'm using subprocessto execute adb commands in shell. Here is the simplified example:
在为 Android Debug Bridge (ADB) 开发 python 包装库时，我使用子进程在 shell 中执行 adb 命令。这是一个简化的例子：
import subprocess
...
def exec_adb_command(adb_command):
return = subprocess.call(adb_command)
If command executed propery exec_adb_commandreturns 0 which is OK.
如果命令执行属性 exec_adb_command返回 0，这是正常的。
But some adb commands return not only "0" or "1" but also generate some output which I want to catch also. adb devicesfor example:
但是一些 adb 命令不仅返回“0”或“1”，而且还生成一些我也想捕获的输出。以 adb 设备为例：
D:\git\adb-lib\test>adb devices
List of devices attached
07eeb4bb device
I've already tried subprocess.check_output()for that purpose, and it does return output but not the return code ("0" or "1").
我已经为此目的尝试了subprocess.check_output()，它确实返回输出但不返回代码（“0”或“1”）。
Ideally I would want to get a tuple where t[0] is return code and t[1] is actual output.
理想情况下，我希望得到一个元组，其中 t[0] 是返回码，而 t[1] 是实际输出。
Am I missing something in subprocess module which already allows to get such kind of results?
我是否在 subprocess 模块中遗漏了一些已经允许获得这种结果的东西？
Thanks!
谢谢！
采纳答案by Padraic Cunningham
Popen and communicate will allow you to get the output and the return code.
Popen 和communication 将允许您获得输出和返回码。
from subprocess import Popen,PIPE,STDOUT
out = Popen(["adb", "devices"],stderr=STDOUT,stdout=PIPE)
t = out.communicate()[0],out.returncode
print(t)
('List of devices attached \n\n', 0)
check_output may also be suitable, a non-zero exit status will raise a CalledProcessError:
check_output 也可能适用，非零退出状态将引发 CalledProcessError：
from subprocess import check_output, CalledProcessError
try:
out = check_output(["adb", "devices"])
t = 0, out
except CalledProcessError as e:
t = e.returncode, e.message
You also need to redirect stderr to store the error output:
您还需要重定向 stderr 以存储错误输出：
from subprocess import check_output, CalledProcessError
from tempfile import TemporaryFile
def get_out(*args):
with TemporaryFile() as t:
try:
out = check_output(args, stderr=t)
return 0, out
except CalledProcessError as e:
t.seek(0)
return e.returncode, t.read()
Just pass your commands:
只需传递您的命令：
In [5]: get_out("adb","devices")
Out[5]: (0, 'List of devices attached \n\n')
In [6]: get_out("adb","devices","foo")
Out[6]: (1, 'Usage: adb devices [-l]\n')
