How to install various versions of Python on Linux Ubuntu system image

Many of us are using Python tools to process various data. After all, there are many things that Python can do currently. Many software are written in a PYTHON environment, but some software requires different versions of Python to support it. Here we need to install the required version on the VPS server and record it. If we also need it, we will see how to follow it. Of course, we installed it based on the Ubuntu environment.

The current default version of Python is 2.7, here we need to install version 3.4. Let’s install the management tools first

$ 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 check the python versions that can be installed through the following command:

$ 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. This must be installed, and 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

This command will download the python source code from github, extract it to the /tmp directory, and then perform the compilation work 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.

Notes:

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 using pip to install third-party modules, they will be installed under ~/.pyenv/versions/3.4.3 and will not conflict with system modules;

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

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