Switching between python virtual environments

Question

I have some noob level virtual environment questions. I've been using virtual environments a little but still have a few questions.

I have created and activated an env which is my main working environment as follows:

virtualenv env
source /path/to/environment/env/bin/activate

Having activated this, I can now see I am in the environment as I have (env) visible on command line.

My first question is, do I need to run the activate command each time I open a terminal session? And therefore each time I turn my laptop on, etc.?

Further, I want to create another environment that runs on an earlier version of python for testing purposes. I was intending to do it as follows:

virtualenv --python=python2.7 env-py2
source /path/to/new/environment/env-py2/bin/activate

Can these virtualenvs be switched easily? So can I activate env-py2 and then easily jump back to activate env again? Or is there an inbetween step required?

Apologies for the very basic questions but I was struggling to find high level information.

Answer 1

Yes you need to run activate command i.e. source each time you open a terminal session.

Switching between two virtual environment is easy. You can run deactivate command and source the other virtual environment.