How to change python version on ubuntu 18.04

change-python-version.md

How to change python version on ubuntu 18.04

• Use update-alternatives
• Change python command path

Check python version and path

1. Check python2 and python3 version

# Python2
> python --version
Python 2.7.17

# Python3
> python3 --version
Python 3.6.9

2. Check python command location

# Python2
> which python
/usr/bin/python

# Python3
> which python3
/usr/bin/python3

Change python command path using update-alternatives

1. Python2

> sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1

2. Python3

> sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2

Check and setup python command path

Change default python

> sudo update-alternatives --config python
There are 2 choices for the alternative python (providing /usr/bin/python).

  Selection    Path                Priority   Status
------------------------------------------------------------
  0            /usr/bin/python3.6   2         auto mode
  1            /usr/bin/python2.7   1         manual mode
* 2            /usr/bin/python3.6   2         manual mode
There are 2 choices for the alternative python (providing /usr/bin/python).

  Selection    Path                Priority   Status
------------------------------------------------------------
  0            /usr/bin/python3.6   2         auto mode
  1            /usr/bin/python2.7   1         manual mode
* 2            /usr/bin/python3.6   2         manual mode

Press <enter> to keep the current choice[*], or type selection number: 2

Let me check default python

> python --version
Python 3.6.9