Python2.7 到 Python3 Ubuntu 切换

Question

I would like to install graph tool on ubuntu. Therefore I want to make the default version of python to 3.7 instead of 2.7 because my compiler give me the error, that the python interpreter is to old to run the configure.

So do u know an solution?

Thanks a lot

Answer 1

If you need to execute Python3 when you run the python command, the easiest way to do it is create an alias like this:

alias python=python3

But you don't need to mess with it, maybe you can launch the configurations and run programs with python3 command instead of python .

Answer 2

python3 file.py

或者将#!/usr/bin/python3添加到代码的第一行以使用 python 3 自动运行它。

Answer 3

I'll recommend not using aliases nor changing defaults. Those things have a way of coming back to bite you later on.

By your description, you said that the tool said the interpreter was too old. I'll guess that it needs a python3 interpreter. So what you should do is a simple sudo apt install python3 and use python3 instead of python when running the code from the terminal.

Example:

Instead of python manage.py runserver

Do... python3 manage.py runserver

Answer 4

1. List all the installed versions of Python 3: ls /usr/bin/python3*

2. Add Python 3.7 to the alternatives list and change its priority: sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.7 1

3. Change the default version of Python by using following command:

   sudo update-alternatives --config python

Type the number of the version you wish to set as default and confirm with enter.

4. Double check, that the change was successfully introduced by: python -V