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I have a virtualenv created for Python 2.5 and want to "upgrade" it to Python 2.6.

Here is how it was originally set up: 

virtualenv --no-site-packages -p python2.5 myenv

I now run virtualenv in the same directory to upgrade: 

virtualenv --no-site-packages -p python2.6 myenv
...
Not overwriting existing python script myenv/bin/python (you must use myenv/bin/python2.6)
...
Overwriting myenv/bin/activate with new content

The default python is still 2.5, even though I can also specify 2.6. Is there any way to remove 2.5 entirely and have 'bin/python' point to 2.6 instead?

Matt Norris
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    In 2021, I guess the best bet is to just make a new venv and reinstall the dependencies - may other SO answers (including using `upgrade`) may not be apt – Anupam Feb 01 '21 at 09:55

6 Answers6

72

You can use the Python 2.6 virtualenv to "revirtual" the existing directory. You will have to reinstall all the modules you installed though. I often have a virtual directory for developing a module, and virtualenv the same directory with many versions of Python, and it works just fine. :)

Lennart Regebro
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    Thanks! I tried your method and see that the 'activate' script is updated, but the old version remains (please see the revised question). Are you able to provide an example? – Matt Norris Jan 31 '10 at 14:13
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    you can just remove the bin/python executable in the virtualenv before re-running virtualenv with python 2.6. – Carl Meyer Jan 31 '10 at 16:42
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    Well, you *can* make it work - but why? The big attraction of `virtualenv` is that it easily and cheaply makes reproducible python environments. Why muck with one and not be certain you've fixed up everything or that you can reproduce it again or that you're disturbing your production environment when you can just make a new clean one? – Ned Deily Jan 31 '10 at 20:56
  • @Wraith: You can just delete bin/python before running virtualenv, or just delete it afterwards and make a new soft-link to bin/python2.6 – Lennart Regebro Jan 31 '10 at 21:26
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    @Ned: Virtualenv doesn't make reproducible environments, it makes isolated environments. To reproduce them you need also to install everything the same way, virtualenv isn't enough for that. zc.buildout is better there. – Lennart Regebro Jan 31 '10 at 21:28
  • @Lennart: `Isolated` is indeed a better description. Even so, the other points still stand. – Ned Deily Jan 31 '10 at 21:51
  • @Ned: I agree I wouldn't do this for a production environment, but then I would use buildout for production anyway, and also typically separate compiled Pythons, which makes virtualenv completely superfluous. :) – Lennart Regebro Jan 31 '10 at 23:13
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    @Ned: Point taken; this is a development environment I was working in. I wanted to keep it in 2.5 unless I absolutely needed to do 2.6. That need arose, so I was curious if you could upgrade an isolated environment to see the effects on your code, without having to rebuild and copy/paste directories to the new env. – Matt Norris Feb 02 '10 at 01:16
  • You must also remove .Python in the directory. This may be because I'm using virtualenvwrapper – lababidi Oct 04 '15 at 15:55
  • I don't get it. Could you provide some commands? – emeraldhieu Jan 10 '23 at 18:16
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    @emeraldhieu Just rerun virtualenv, and then reinstall the packages it had installed. – Lennart Regebro Jan 11 '23 at 20:53
55

In Python 3.3+ venv supports --upgrade flag

  --upgrade             Upgrade the environment directory to use this version
                        of Python, assuming Python has been upgraded in-place.

Usage:

python -m venv --upgrade YOUR_VENV_DIRECTORY

I just upgraded my venv from Python 3.7.x to 3.8 on several projects without any issue.

Vlad Bezden
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    "assuming Python has been upgraded in-place" ... this unfortunately seems to mean that if my system `python3` points to 3.6, i can't create get `python3` to point to 3.7 in my venv – joel Feb 16 '20 at 17:33
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    @joel I've not tried it yet, but would `/path/to/user/python -m venv --upgrade` work? – ospider Jun 29 '21 at 08:25
  • I don't know if this counts as a graceful upgrade, because it doesn't do anything about the packages installed in the old site-package directory. Thus, since you still need to re-install them it isn't much won in comparison with just recreating the whole virtual environment ... – maxschlepzig May 08 '22 at 12:32
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    Wanted to move my venv from 3.9 to 3.11 (django project) . This command didn't generate any error but `print(sys.version)` in a views.py still shows `3.9.14`. Tried with python -m ... python3 -m ... python3.11 -m, with same result. Each time I deactivate + activate my venv. Without success – Abpostman1 Dec 30 '22 at 08:49
  • Hm... The docs says "Deprecated since version 3.6: pyvenv was the recommended tool..." – emeraldhieu Jan 10 '23 at 18:19
4

You should create a new virtualenv using python2.6 and then, after activating the new env, use its python2.6 and its easy_install to install new versions of any site packages you need. Beware that the path name to the virtualenv is hardwired into various files within the environment, so, when you are ready to switch over to it, either change your startup scripts et al to refer to the new virualenv path or be very careful about copying it over to the old directory and modifying the path names inside it.

Ned Deily
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3

You can simply do this by go to your venv file and change the python path and it's version from pyvenv.cfg like this:enter image description here

Muhammed Ahmed Abd Al Aleam
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  • Try not to paste images if its not necessary. The details in the answer should be entered as text – moken Dec 27 '22 at 03:58
  • While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - [From Review](/review/late-answers/33500184) – コリン Dec 28 '22 at 07:15
2

Install a second Python on CentOS

  1. download python

  2. install to diff local

    configure --prefix=/opt/virtualenv/python 
make && make install

  3. create virtual env using new python

    virtualenv /opt/virtualenv --python=/opt/python276/bin/python

    note: if needed it can be done with a different user

    chown pyuser -R /opt/virtualenv
su - pyuser
source /opt/virtualenv/bin/activate
python -v

  4. Create virtual env:

    virtualenv /opt/virtualenv
su - infograficos
source bin/activate

  5. Install pip with python 2.7 (inside virtualenv)

    easy_install pip
BenjaminGolder
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Xoroz
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0

If you're using OS X, try this if you want to upgrade Python to a minor-increased version (e.g. 2.7.6 to 2.7.8) while keeping third-party libraries work.

It work for me on 5 different virtual environments with Django installed.

Community
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Rockallite
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