How to export PYTHONPATH when I activate a virtual environment on pyenv-virtualenv?

Question

I am using pyenv and its plugin pyenv-virtualenv .

My questions is: How to modify PYTHONPATH environment variable when I activate some virtual environment on pyenv-virtualenv?

$ pyenv activate myenv
$ echo $PYTHONPATH  # I want this variable!

When I used simple virtualenv, I could modify PYTHONPATH via editing virtualenv_home/your_env/bin/activate

export OLD_PYTHONPATH=$PYTHONPATH
export PYTHONPATH="/path/to/you/want"

Which file should I edit for pyenv-virtualenv?

Answer 1

You simply set PYTHONPATH as per normal, whether that is in your shell startup script or elsewhere. When you switch to a pyenv-controlled virtualenv with pyenv virtualenv , it will automatically append all the necessary directories for this virtualenv to sys.path , but any directories you defined in the PYTHONPATH variable will precede them.

Added based on discussion in comments below:

You can create hook scripts for a given pyenv command <command> in $PYENV_HOME/pyenv.d/<command>/ . You can even do this for pyenv's “porcelain” commands which aren't normally called directly by the user.

It should be possible to create a hook for activate (which is implicitly called by pyenv-virtualenv when switching to a virtualenv) which parses the name of the virtualenv and sets $PYTHONPATH based on that.

Note: I've written pyenv hooks before but haven't explicitly tested this solution.