如何在 Python 中捕获 subprocess.check_call 的返回码

Question

I have a script that is executing 5 different shell commands and I'm using subprocess.check_call() to execute them. The problem is that I can't seem to figure out how to properly capture and analyze the return code.

According to the docs The CalledProcessError object will have the return code in the returncode attribute. , but I don't understand how to access that. If I say

rc = subprocess.check_call("command that fails")
print(rc)

It tells me

subprocess.CalledProcessError: Command 'command that fails' returned non-zero exit status 1

But I can't figure out how to capture just the integer output of 1.

I'd imagine this must be doable somehow?

Answer 1

Whenever the subprocess.check_call method fails is raises a CalledProcessError . From the docs:

subprocess.check_call(args, *, stdin=None, stdout=None, stderr=None, shell=False, cwd=None, timeout=None, **other_popen_kwargs)

Run command with arguments. Wait for command to complete. If the return code was zero then return, otherwise raise CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute.

You may just want subprocess.run or to use a try/except block to handle the CalledProcessError

perhaps

rc = subprocess.run("some_cmd").returncode

or

try
...
    rc = subprocess.check_call("command that fails")
except CalledProcessError as error:
    rc = error.returncode

Answer 2

With check_call you'll have to add a try/except block and access the exception. With subprocess.run you can access the result without a try/except block.

import subprocess

try:
    subprocess.check_call(["command", "that", "fails"])
except subprocess.CalledProcessError as e:
    print(e.returncode)

Or using subprocess.run :

result = subprocess.run(["command", "that", "fails"])
print(result.returncode)