Search a directory for virtual environments that use pyenv-managed versions of Python.

I find it helpful for verifying that I can safely uninstall old Python versions. Unlike the pyenv-virtualenv plugin, this will list all virtual environments, regardless of how they were created (python -m venv <venv>, poetry install, etc).

• GNU coreutils (for readlink and realpath)
• GNU findutils (for find)

$ git clone https://github.com/pyenv/pyenv-users.git "$(pyenv root)/plugins/pyenv-users"

Run pyenv users to search the current directory for virtual environments, or pyenv users <directory> to search a specific directory. For example, to search your home directory:

$ pyenv users ~
3.7.9 .cache/pypoetry/virtualenvs/my_project-KM_3YcvM-py3.7
3.7.9 work/venvs/long name with spaces
3.8.6 .cache/pypoetry/virtualenvs/my_project-KM_3YcvM-py3.8
pypy3.6-7.3.1 work/venvs/example1

For scripting, use the --raw option to output a list of : separated items. The --absolute-paths option may also be useful in this case:

$ pyenv users --raw --absolute-paths ~
3.7.9:/home/peter/.cache/pypoetry/virtualenvs/my_project-KM_3YcvM-py3.7
3.7.9:/home/peter/work/venvs/long name with spaces
3.8.6:/home/peter/.cache/pypoetry/virtualenvs/my_project-KM_3YcvM-py3.8
pypy3.6-7.3.1:/home/peter/work/venvs/example1

For example, to get a list of all versions linked to a virtual environment:

$ pyenv users --raw ~ | cut -d: -f1 | uniq
3.7.9
3.8.6
pypy3.6-7.3.1

The list of linked versions can be combined with the list of all installed versions to show which installations are not linked to any environment in the specified directory:

$ pyenv versions --bare
3.6.10
3.7.5
3.7.9
3.8.6
3.9.1
pypy3.6-7.3.0
pypy3.6-7.3.1
$ comm -3 <(pyenv users --raw ~ | cut -d: -f1 | uniq) <(pyenv versions --bare) | tr -d "[:blank:]"
3.6.10
3.7.5
3.9.1
pypy3.6-7.3.0

The plugin doesn't maintain a list of environments; it generates the list each run by performing a brute force scan of the directory for symlinks named python. This does mean it's not blazingly fast, but its simplicity provides state-free reliability, and in practice find only takes a few seconds.

Also, it could really use more testing; so far I've been using it on Fedora 33 with no issues. Tested with bash v5.0.17(1) and find v4.7.0.