Fabric'll do that for you (or rather Invoke, I guess I should say as part of the Fabric 2 changes)

    >>> from invoke import run
    >>> date = run("date")
    Sat Apr 13 11:09:18 PDT 2019
    >>> dir(date)
    ['__bool__', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__nonzero__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'command', 'encoding', 'env', 'exited', 'failed', 'hide', 'ok', 'pty', 'return_code', 'shell', 'stderr', 'stdout']
    >>> date.return_code
    0
    >>> date.stdout
    'Sat Apr 13 11:09:18 PDT 2019\n'
    >>> do_they_exist = run("grep banana /etc/passwd")
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/Users/pgraydon/Envs/python3/lib/python3.7/site-packages/invoke/__init__.py", line 46, in run
        return Context().run(command, **kwargs)
      File "/Users/pgraydon/Envs/python3/lib/python3.7/site-packages/invoke/context.py", line 94, in run
        return self._run(runner, command, **kwargs)
      File "/Users/pgraydon/Envs/python3/lib/python3.7/site-packages/invoke/context.py", line 101, in _run
        return runner.run(command, **kwargs)
      File "/Users/pgraydon/Envs/python3/lib/python3.7/site-packages/invoke/runners.py", line 271, in run
        return self._run_body(command, **kwargs)
      File "/Users/pgraydon/Envs/python3/lib/python3.7/site-packages/invoke/runners.py", line 404, in _run_body
        raise UnexpectedExit(result)
    invoke.exceptions.UnexpectedExit: Encountered a bad command exit code!
    
    Command: 'grep banana /etc/passwd'
    
    Exit code: 1
    
    Stdout: already printed
    
    Stderr: already printed

If it gets a non-zero code back (like grep does when it fails to get a match), it raises an UnexpectedExit exception.