Update Alternatives in Linux
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Date: November 20, 2021

[code]
  update-alternatives --query python

[code]
  update-alternatives: error: no alternatives for python

[code]
  sudo update-alternatives --install /usr/local/bin/python python `which python3.8` 2
  # update-alternatives: using /usr/bin/python3.8 to provide /usr/local/bin/python (python) in auto mode

  sudo update-alternatives --install /usr/local/bin/python python `which python2.7` 5
  # update-alternatives: using /usr/bin/python2.7 to provide /usr/local/bin/python (python) in auto mode

  update-alternatives --query python
  # Name: python
  # Link: /usr/local/bin/python
  # Status: auto
  # Best: /usr/bin/python2.7
  # Value: /usr/bin/python2.7
  #
  # Alternative: /usr/bin/python2.7
  # Priority: 5
  #
  # Alternative: /usr/bin/python3.8
  # Priority: 2

  sudo update-alternatives --install /usr/local/bin/python python `which python3.8` 20
  # update-alternatives: using /usr/bin/python3.8 to provide /usr/local/bin/python (python) in auto mode