It is useful to have both a return code and output of the command.
Add a new wrapper rc_cmd that returns both:
>>> rc_cmd('uname')
(0, 'Linux')
>>>
>>> rc_cmd('sudo ip --json --brief link show dev noname')
(1, 'Device "noname" does not exist.')
>>>PR https://github.com/vyos/vyos-1x/pull/1442
>>> from vyos.util import rc_cmd
>>>
>>> rc_cmd('uname')
(0, 'Linux')
>>>
>>> rc_cmd('ip link show dev fake')
(1, 'Device "fake" does not exist.')
>>>Ex2
>>> rc, command = rc_cmd('ip link show dev eth999')
>>>
>>>
>>> print(rc)
1
>>> print(command)
Device "eth999" does not exist.
>>>