Methods and precautions for installing multiple versions of Python under ubuntu

Today I accidentally damaged the ubuntu system again because I uninstalled python3, and then... . . Okay, without further ado, let’s talk about how to manage multiple versions of Python under Ubuntu. What I use here is a Python version management tool called pyenv.

System environment: ubuntu14.04LTS. The default python version of the system is 2.7. I want to install another version 3.4.3 here.

Before installing python, we must first install the management tool pyenv:

$ git clone git://github.com/yyuu/pyenv.git ~/.pyenv
$ echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
$ echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
$ echo 'eval "$(pyenv init -)"' >> ~/.bashrc
$ exec $SHELL -l

We can also use the following command to view the python versions that can be installed:

$ pyenv install --list

If we are sure to install python3.4.3, then we can install python, but before installation, we must install the dependency packages required by python, which must be installed , the installation will fail:

$ sudo apt-get install libc6-dev gcc
$ sudo apt-get install -y make build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm

After the above dependency packages are completed, we can install python:

$ pyenv install 3.4.3 -v

The command will start from Download the python source code from github, extract it to the /tmp directory, and then perform compilation in /tmp. If the dependent package is not installed, a compilation error will occur, and you need to re-execute the command after installing the dependent package.

After the installation is complete, you need to use the following command to update the database:

$ pyenv rehash

View the currently installed python version

$ pyenv versions
* system (set by /home/seisman/.pyenv/version)
3.4.3

The asterisk represents the python version currently being used by the system, which comes with the system.

Set the global python version

$ pyenv global 3.4.3
$ pyenv versions
system
* 3.4.3 (set by /home/seisman/.pyenv/version)

From the above, we can see that the current python version has changed to 3.4.3. You can also use pyenv local or pyenv shell to temporarily change the python version.

Confirm python version

$ python
Python 3.4.3 (default, Apr 1 2015, 19:10:43)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.

Note:

Enter python to use the new version of python;

The system's own script will directly call the old version of python in /usr/bin/python, so it will not affect the system script;

When you use pip to install third-party modules, they will be installed to~ /.pyenv/versions/3.4.3, there will be no conflict with system modules;

After using pip to install the module, you may need to execute pyenv rehash to update the database.

The above is the method and precautions for installing multiple versions of Python under ubuntu introduced by the editor. I hope it will be helpful to you. If you have any questions, please leave me a message and the editor will reply in time. Ours. I would also like to thank you all for your support of the PHP Chinese website!

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