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How do I update a virtualenv?

Ned Batchelder ned at nedbatchelder.com
Mon Oct 28 20:13:35 EDT 2013 
On 10/28/13 7:53 PM, Skip Montanaro wrote:
>> Virtualenvs aren't built to be moved from one Python installation to
>> another.  If you used pip to install your packages (you should), then you
>> can activate the virtualenv, and run: $ pip freeze > requirements.txt
>>
>> Then you can create a new virtualenv using the new Python executable,
>> activate it, and:  $ pip install -r requirements.txt
>>
>> This will reinstall all the packages you had installed previously. Even
>> better is to maintain your own requirements.txt that has just the packages
>> you need.  The "pip freeze" technique will also list packages installed as
>> dependencies.
> Hmmm... And my git repo?
Usually the virtualenv is outside the git repo (and vice-versa), but git 
repos are also easy to recreate from the git server if you need to.  
Maybe I don't understand what you mean?

> I imagine I will eventually figure this out,
> but updating an existing virtualenv in place to adapt to a new version
> of Python (say, a new micro) or some of its libraries (contents of
> requirements.txt) seems like it would be a very nice thing to have.

"pip install --upgrade" will upgrade your Python packages.  "pip install 
-r requirements.txt"  will install new packages or versions named in the 
requirements.txt file.

> Skip

--Ned.
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