After I wrote about Python virtual environments and source code trees , I impulsively decided to set up the development tree of our Django application to use a Django venv instead of a 'pip install --user' version of Django. Once I started doing this, I quickly decided that I wanted a general script that would switch me into a venv. This sounds a little bit peculiar if you know Python virtual environments so let me explain.

Activating a Python virtual environment mostly means making sure that its 'bin' directory is first on your $PATH, so that 'python3' and 'pip' and so on come from it . Venvs come with files that can be sourced into common shells in order to do this (with the one for Bourne shells called 'activate'), but for me this has three limits. You have to use the full path to the script, they change your current shell environment instead of giving you a new one that you can just exit to discard this 'activation', and I use a non-standard shell that they don't work in. My ' venv ' script is designed to work around all three of those limitations. As a script, it starts a new shell (or runs a command) instead of changing my current shell environment, and I set it up so that it knows my standard place to keep virtual environments (and then I made it so that I can use symbolic links to create 'django' as the name of 'whatever my current Django venv is').

(One of the reasons I want my ' venv ' command to default to running a shell for me is that I'm putting the Python LSP server into my Django venvs , so I want to start GNU Emacs from an environment with $PATH set properly to get the right LSP server.)

My initial version only looked for venvs in my standard location for development related venvs. But almost immediately after starting to use it, I found that I wanted to be able to activate pipx venvs too, so I added ~/.local/pipx/venvs to what I really should consider to be a 'venv search path' and formalize into an environment variable with a default value.

I've stuffed a few other features into the venv script. It will print out the full path to the venv if I ask it to (in addition to running a command, which can be just 'true'), or something to set $PATH. I also found I sometimes wanted it to change directory to the root of the venv. Right now I'm still experimenting with how I want to build other scripts on top of this one, so some of this will probably change in time.

One of my surprises about writing the script is how much nicer it's made working with venvs (or working with things in venvs). There's nothing it does that wasn't possible before, but the script has removed friction (more friction than I realized was there, which is traditional for me).

PS: This feels like a sufficiently obvious idea that I suspect that a lot of people have written 'activate a venv somewhere along a venv search path' scripts. There's unlikely to be anything special about mine, but it works with my specific shell .