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I have python 2.7 and 3.4 versions installed. But when I say say "python -V", it shows version as 2.7 not 3.4

How to tell ubuntu to use newest python? where is this setting configured ?

Sachin Doiphode
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    You don't. The `python` command will always be Python 2.x. If you want Python 3.x, you should use the `python3` command to run it. Changing the `python` command will break all Python 2.x applications. – dobey Sep 24 '14 at 17:54
  • @FlorianDiesch At first sight definitely, but OP doesn't want a permanent change, but just wants to know how to define which version to use, running the code (see comment on the answer) – Jacob Vlijm Sep 24 '14 at 18:23

1 Answers1

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if you run python -V, you get: Python 2.7.6, However, if you run python3 -V, you get 3.4.0.

Running a script, you can specify the python version to use by using either:

python <script.py>

or:

python3 <script.py>

If the script or application is executable, and you run it without the python (either 2 or 3) command, you need to have the shebang in your script, in which you define the python version to use; either:

#!/usr/bin/env python

or:

#!/usr/bin/env python3

You cannot run code, written for python2 with python3 and vice versa, so you should not (try to) "tell" Ubuntu to use either version 2 or 3 in another way then above, according to the version of python, used in your code.

Jacob Vlijm
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