pyenv
This method does not use apt-get, but it is, I believe, the best option available today, as it can easily compile any Python version from source for you, so you don't have to rely on any PPAs.
https://github.com/pyenv/pyenv
Pyenv allows you to manage multiple Python versions without sudo for a single user, much like Node.js NVM and Ruby RVM.
Install Pyenv:
curl https://pyenv.run | bash
Then add to your .bashrc:
export PATH="${HOME}/.pyenv/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"
Find Python version to install:
pyenv install --list
Install the python version you want:
# Increase the chances that the build will have all dependencies.
# https://github.com/pyenv/pyenv/wiki/Common-build-problems
sudo apt build-dep python3
sudo apt-get install -y make build-essential libssl-dev zlib1g-dev libbz2-dev \
libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
xz-utils tk-dev libffi-dev liblzma-dev python-openssl git
Build and install a Python version from source.
pyenv install 3.8.0
List available Python versions:
pyenv versions
We now have:
* system (set by /home/cirsan01/.pyenv/version)
3.8.0
Select a different python version:
pyenv global 3.8.0
python --version
python3 --version
Both output:
Python 3.8.0
We can now proceed to install and use packages normally:
pip install cowsay
python -c 'import cowsay; cowsay.tux("Python is fun")'
cowsay 'hello'
We can confirm that everything is locally installed in our clean environemnt with:
python -c 'import cowsay; print(cowsay.__file__)'
which cowsay
We see that which python points to:
~/.pyenv/shims/python
because ~/.pyenv/shims is prepended to PATH with the rc scripts.
TODO understand further. The global version is somethow determined by:
~/.pyenv/version
which now contains:
3.8.0
Per project usage
In the previous section, we saw how to use pyenv in a global setup.
However, what you usually want is to set a specific python and package version on a per-project basis. This is how to do it.
First install your desired Python version as before.
Then, from inside your project directory, set the desired python version with:
pyenv local 3.8.0
which creates a file .python-version containing the version string.
And now let's install a package locally just for our project: TODO: there is no nice way it seems: https://stackoverflow.com/questions/30407446/pyenv-choose-virtualenv-directory/59267972#59267972
Now, when someone wants to use your project, they will do:
pyenv local
which sets the Python version to the correct one.
Tested on Ubuntu 18.04, pyenv 1.2.15.
Conda
I'm not a huge fan of conda's bloatedness, but for better or worse it has become a popular way to manage Python versions and prebuilt shared libraries.
Install miniconda on Linux with:
mkdir -p ~/miniconda3
wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh -O ~/miniconda3/miniconda.sh
bash ~/miniconda3/miniconda.sh -b -u -p ~/miniconda3
rm ~/miniconda3/miniconda.sh
and add this to your .bashrc:
PATH="$PATH:$HOME/miniconda3/bin"
then to create a new environment for a project with a specific Python version:
conda create -y -n mytest3.9 python=3.9
and then for each shell where you want to use it in:
eval "$(command conda 'shell.bash' 'hook' 2> /dev/null)"
conda activate mytest3.9
then:
python --version
gives:
Python 3.9.21
and:
which python
gives:
/home/ciro/miniconda3/envs/mytest3.9/bin/python
It also ships its own pip:
which pip
giving:
/home/ciro/miniconda3/envs/mytest3.9/bin/pip
from which you can pip install as in a virtualenv.
You can also let conda modify your .bashrc automatically for you with:
conda init
but unfortunately the code it adds automatically puts you into Conda on every shell which I don't like, so I prefer to do the eval manually per shell as mentioned at: https://stackoverflow.com/questions/55507519/python-activate-conda-env-through-shell-script
Tested on conda 25.1.1, Ubuntu 24.10.
Ultimate mega master compatibility table
OK let's do this:
Python 3.x
+-----------------+
| 13 12 11 10 9 8 |
+-------+-----------------+
| 25.04 | D M |
| 24.10 | M D |
| 24.04 | D |
| 22.04 | M D |
| 20.04 | M D |
+-------+-----------------+
Search for official PPAs
Installing python: who is deadsnakes and why should I trust them? asks if the popular deadsnakes PPA is trustworthy. While it is not maintained by Canonical employees directly (huge missed opportunity!), at least one of the developers, Anthony Sottile, has a video of hiself presenting the project: https://www.youtube.com/watch?v=Xe40amojaXE So at least we know that if it is a SCAM we have at least one American head to go after which gives it some confidence.
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