Python deployments
Check Python
Check the version of the default Python interpreter:
python --version
List the versions of python available:
ls /usr/bin/python*
Use update-alternatives to setup system-wide ability to choose Python interpreter. The one with the higher priority number will become the default.
update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2
Now we can list the choices:
update-alternatives --list python
And choose one:
update-alternatives --config python
We can also remove a choice if it's no longer an option on the system:
update-alternatives --remove python /usr/bin/python2.7
Python Virtual Environments
See Digital Ocean's quick guide to setting up a local Python programming environment, including virtual environments, which is what I did for SoundScrape Btw, SoundScrape is a neat tool to download sound files from SoundCloud. [1]
Hynek Schlawack (from 2013)
Python Packaging
In the old days (2015) there were still debates about how to package Python and install stuff. Now, it's settled. Use pip. Easy_install is dead. See the docs. Also note that venv is the successor to virtualenv
Basic PIP and Virtual Environments
Do NOT (normally) use sudo with pip. Use a virtual environment. As of Python 3.4, the command is now called pyvenv or simply venv. As of Python 3.6 pyvenv is deprecated in favor of using python3 -m venv to help prevent any potential confusion as to which Python interpreter a virtual environment will be based on. python3 is not generic. It represents the exact version you wish to use in your virtual environment.
As an example, I needed to create a Python Virtual Environment to use the Ansible Playbook Grapher
python3.11 -m venv myenv
# .. some output ..
source myenv/bin/activate
# maybe upgrade pip
pip install --upgrade pip
# then install your local environment packages
pip install what-i-want
# done using this python?
deactivate
You only use sudo or elevated permissions when you want to install stuff for the global, system-wide Python installation.
It is best to use a virtual environment which isolates packages for you. That way you can play around without polluting the global python install.
As a bonus, virtualenv does not need elevated permissions.
- Installing a package is as simple as
pip install foo - Upgrades are
pip install --upgrade foo pip uninstall fooif you want to remove foo
References
- ↑
cd mkdir environments cd environments/ pyvenv my_env source my_env/bin/activate pip install --upgrade pip pip install soundscrape pip install soundscrape --upgrade soundscrape https://soundcloud.com/pianoman_weddings/coldplay
