How this works is that the latest 2. So if you have multiple 2. The same applies for a generic 3: the latest Python version in the 3. For example, if you have Python 2. In this case, that script will run against Python 2. You could change this operation by:. This probably seems odd behavior but I think the rationale here is two-fold. One is that many people using a Python ecosystem are still stuck in the 2. So a default of Python 2 may make sense. Second is that Unix-based versions tend to rely on symbolic links from python to a specific version and that tends to be a 2.
So I think the Windows launcher is trying to emulate the most likely use case for Python developers, but this can come at the expense of newcomers to Python. Earlier, in particular with shebang lines, I mentioned there was a caveat that I would mention. That particular caveat is that the new Windows launcher recognizes Unix! It seems the launcher requires you to follow one of the following patterns:.
Another caveat to be aware of is that if there are both shebang lines in the Python script and a version number switch is provided in the command line used to execute that script, the command line version will override that specified in the shebang line.
Note that both launchers should have automatically disabled setting the PATH to a location of python. This is important as well. Another caveat, although a potential useful one, is that the launcher will also let you distinguish between bit and bit versions of Python that are installed. So I can have Python 2.
Using the launcher would allow me to distinguish between all of those. The launcher turns that around and always attempts to use the latest version that it can find on the machine. If you request a version of Python that is not installed, you will get an error message along the lines of Requested Python version 2.
Beyond that, I have not found too many other caveats worthy of mention. If Python is your language of choice, but you are worried about the 2. If you also want to work with Python 2 , then pyenv-virtualenv is a tool to consider. From Python 3. It is ideal for creating lightweight virtual environments. Up until Python 3. It will be completely removed in Python 3.
The exact same functionality is available when using venv , and any existing documentation should be updated. For anyone interested you can read the reasons behind depreciating pyvenv. By default, the environment it creates will be the current version of Python you are using. If you are writing documentation, and want the additional safety that the correct version of Python is being used by your reader you can specify the major and minor version number in the command, like so:.
If the reader is using a version other than 3. However, any patch version for example 3. When the environment is active, any packages can be installed to it via pip as normal. By default, the newly created environment will not include any packages already installed on the machine. As pip itself will not necessarily be installed on the machine. It is recommended to first upgrade pip to the latest version, using pip install --upgrade pip.
Projects will commonly have a requirements. This allows the shortcut command pip install -r requirements. They will only exist in the virtual environment. Tweet a thanks. Learn to code for free. Get started. Forum Donate. Dalya Gartzman. X -V pip X. Rotareti Rotareti There seems to be a bug using asdf with poetry: github. The commands below are for Mac but pretty similar to Linux see the links below Install pyenv brew update brew install pyenv Let's say you have python 3.
Kohn Kohn 2, 19 19 silver badges 24 24 bronze badges. How to install different Python versions is indeed OS dependent. Rodrigue Rodrigue 3, 2 2 gold badges 37 37 silver badges 49 49 bronze badges. No problems so far. Roland pyenv will work for that. Package Managers - user-level For a package manager that can install and manage multiple versions of python, these are good choices: pyenv - only able to install and manage versions of python asdf - able to install and manage many different languages The advantages to these package managers is that it may be easier to set them up and install multiple versions of python with them than it is to install python from source.
Installation from source - system-wide You'll need root privileges for this method. Install any build dependencies. On Debian-based systems, use: apt update apt install build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libsqlite3-dev libreadline-dev libffi-dev libbz2-dev Choose which python version you want to install.
Seth Johnson Seth Johnson What is a package distribution system? Basically it is a tool to install software. I installed anaconda navigator and created two different development environments with different python versions and switch between different python versions by switching or activating and deactivating environments. Matteo Zanoni Matteo Zanoni 1, 4 4 silver badges 15 15 bronze badges. Now if you need to create a venv for a specific project, cd your-project python3.
Mendhak Mendhak 7, 5 5 gold badges 49 49 silver badges 61 61 bronze badges. Fedora Linux - simply install from packages Probably worth noting that Fedora distro includes older versions of Python that are not EOL'ed. The packages are described as: Python 3. X package for developers. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.
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