Parse cmd stdout/stderr

[ipmb]

It looks like this:

{
  "stdout": "New python executable in /srv/proj/venvs/298f0caea8e37f4867808fa6ccd2a3e4c7bfcaff/bin/python\nInstalling setuptools, pip, wheel...done.",
  "pid": 17444,
  "retcode": 0,
  "stderr": ""
}