subprocess.check_output(): show output on failure

Question

The output of subprocess.check_output() looks like this at the moment:

CalledProcessError: Command '['foo', ...]' returned non-zero exit status 1

Is there a way to get a better error message?

I want to see stdout and stderr.

Answer 1

Redirect STDERR to STDOUT.

Example from the interpreter:

>>> try:
...   subprocess.check_output(['ls','-j'], stderr=subprocess.STDOUT)
... except subprocess.CalledProcessError as e:
...   print('error>', e.output, '<')
...

Will throw:

error> b"ls: invalid option -- 'j'\nTry `ls --help' for more information.\n" <

Explantion

From check_output documentation:

To also capture standard error in the result, use stderr=subprocess.STDOUT