python - subprocess.check_output return code

Question

I am using:

grepOut = subprocess.check_output("grep " + search + " tmp", shell=True)

To run a terminal command, I know that I can use a try/except to catch the error but how can I get the value of the error code?

I found this on the official documentation:

 exception subprocess.CalledProcessError

    Exception raised when a process run by check_call() or check_output() returns a non-zero exit status.

    returncode

        Exit status of the child process.

But there are no examples given and Google was of no help.

Answer 1

You can get the error code and results from the exception that is raised.

This can be done through the fields returncode and output.

For example:

import subprocess

try:
    grepOut = subprocess.check_output("grep " + "test" + " tmp", shell=True)                       
except subprocess.CalledProcessError as grepexc:                                                                                                   
    print("error code", grepexc.returncode, grepexc.output)