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I have an existing virtualenv with a lot of packages but an old version of Django.

What I want to do is duplicate this environment so I have another environment with the exact same packages but a newer version of Django. How can I do this?

rdegges
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dolma33
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    I would pip freeze all your requirements into a 'requirements.txt' file and create another virtualenv and run pip install requirements.txt – Calvin Cheng Sep 15 '11 at 23:53
  • If the python version of the virtual environment that you want to copy is different from your default python environment, you can setup the new environment as `virtualenv -p /path/to/older/venv/bin/python new_venv` and then use the `requirements.txt` that you generated after `pip freeze` – GiriB Apr 17 '17 at 11:21
  • @CalvinCheng it is "pip install -r requirements.txt" – Ferdi Jan 22 '21 at 10:31

8 Answers8

214

The easiest way is to use pip to generate a requirements file. A requirements file is basically a file that contains a list of all the python packages you want to install (or have already installed in case of file generated by pip), and what versions they're at.

To generate a requirements file, go into your original virtualenv, and run:

pip freeze > requirements.txt

This will generate the requirements.txt file for you. If you open that file up in your favorite text editor, you'll see something like:

Django==1.3
Fabric==1.0.1
etc...

Now, edit the line that says Django==x.x to say Django==1.3 (or whatever version you want to install in your new virtualenv).

Lastly, activate your new virtualenv, and run:

pip install -r requirements.txt

And pip will automatically download and install all the python modules listed in your requirements.txt file, at whatever versions you specified!

JJD
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rdegges
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    what if I copy the folder and then paste it on another machine? It would work? Assuming of course the apt-get dependencies were resolved – Tales Pádua Mar 03 '16 at 21:12
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    Indeed it does not, as I am finding out just now. – horcle_buzz Jul 07 '16 at 18:44
  • I see many messages `Could not find a version that satisfies the requirement a_package=#.#.#` Can I solve it easily? I removed a line or changed the equality to the inequality. – Change-the-world Apr 02 '18 at 08:01
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    Works for `pyenv` as well. Awesome answer. – Leonard Jan 12 '20 at 06:17
  • So far, it sounds like being the best approach for me. – Valentin Mar 16 '21 at 10:30
  • virtualenv-clone worked well for me (answer below) and didn't require recompiling opencv and installing in the new virtualenv. Having said that, requirements.txt is a good answer for more generic environments. – brianlmerritt Mar 15 '22 at 02:22
  • the virtualenv-clone although working seems to retain (in Ubuntu) the name of the old virtualenv in the command prompt. – brianlmerritt Mar 15 '22 at 02:32
  • It works! Pay attention with PyTorch. You have to remove the line where it has been declared in requirements.txt and all its extensions, otherwise it raises an error. You will need to install it from the official command provided by its site – Francesco Laiti Apr 03 '22 at 09:20
37

Another option is to use virtualenv-clone package:

A script for cloning a non-relocatable virtualenv.

alecxe
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  • Hi, am i right to assume this allows me to copy a WHOLE python environment into a file. Then i would just have to load this file in a new computer/OS and i would get all my site packages installed back – aceminer Jun 06 '16 at 05:29
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    "virtualenv-clone source/ target/" worked like a charm thanks! – ajankuv Jun 21 '18 at 18:47
  • make sure we installed `virtualenv-clone` after activating the virtualenv – 4givN Dec 09 '19 at 15:32
  • The syntax is `python -m clonevirtualenv source/ target/` – Georg W. Dec 18 '20 at 18:29
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    This has the benefit of copying opencv, which I had to install from source. I could have done another full make with the new virtual env as the target, but this was a lot simpler. – brianlmerritt Mar 15 '22 at 02:24
17

virtualenvwrapper provides a command to duplicate virtualenv

cpvirtualenv ENVNAME [TARGETENVNAME]
Raymond
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    Not really a good idea. "Copying virtual environments is not well supported. Each virtualenv has path information hard-coded into it, and there may be cases where the copy code does not know it needs to update a particular file. Use with caution." – Temak Nov 14 '17 at 00:11
  • Can you specify a path to the venv instead of the name? – anilbey Feb 11 '21 at 14:32
10

Easiest option is using virtualenv-clone package.

To duplicate venv1 to venv2, follow these steps:

  1. Install virtualenv-clone in either venv1 or a dummy virtual environment venv_dummy. To create venv_dummy:

    python -m virtualenv venv_dummy
source venv_dummy/bin/activate

  2. To install virtualenv-clone:

    (venv_dummy): pip install virtualenv-clone

  3. To duplicate venv1 to venv2:

    (venv_dummy): virtualenv-clone venv1/ venv2/
Safwan
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  • the prompt in bash is not changes, have to edit bin/activate, and not 100% clear how – MrR Jun 14 '20 at 23:25
  • @MrR .. you don't have to edit `bin/activate` if you follow this answer. Why do you have to edit `bin/activate`? – Safwan Jun 15 '20 at 05:45
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    After I've cloned, my prompt in bash had the original environment name, because of the PS1 section within `bin/activate` – MrR Jun 15 '20 at 15:56
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    @MrR That sounds like a bug or oversight in virtualenv-clone but one that shouldn't really affect behavior. – Joe Holloway Aug 04 '20 at 18:20
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    if the name is not changed according to @MrR, then go to the new environments `bin/activate` file and search for the old env name and set the new name. Voila! There will be 2 occurences to rename. Good Luck!! – Sachin Mohan Jan 08 '21 at 16:45
  • Replace the block starting with `if [ -z "${VIRTUAL_ENV_DISABLE_PROMPT:-}" ] ; then` with [this](https://tio.run/##S0oszvj/PzNNIVpBt0pBSaU6zDMoJNTRJ97VLyzexTPY0cnHNT4gyN83IES3VkkhVsFaoSQjNY9LAQji/X1c4mHqA4INbYHagRRQHVgabKhShZKCoq1CBapOEMDUkJpTnIoqrZGQlFicmpeYm6oQo6SC5LQYpQRNBRTNaZkQMyoK8otKQLq50jL//wcA) – MrR Jan 10 '21 at 05:10
9

If you are using Anaconda you can just run:

conda create --name myclone --clone myenv

This will copy myenv to the newly created environment called myclone.

Brad Solomon
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Jordan
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1

In case you use pip "venv". I copy pasted the folder holding the virtual environment and manually changed the files in the bin folder of the copied folder. I don't know if its efficient,but it works!

  • Hello Saai Sudarsanan D and welcome to StackOverflow! Please, have a read on [how to write a good answer](https://stackoverflow.com/help/how-to-answer) – BiOS Feb 28 '21 at 09:31
1

Here is my go to command for cloning python virtual environments.

packs=`source-path/bin/pip freeze` && python3 -m venv <env-name> && target-path/bin/pip install $packs

Conventions used in above command:

  • source-path = path to env that you want to clone e.g. /home/john/envs/oldenv.
  • env-name = name of the cloned env e.g. myenv, it can be a path as well e.g. /home/john/envs/myenv
  • target-path = path to new cloned env e.g. /home/john/envs/<env-name>

Advantages of using this or why i prefer this

  1. No need to generate a requirements.txt file.
  2. No environment is activated/deactivated during cloning process.
  3. single command to be executed(3 commands ran at once).

In some cases you might want to exclude global packages from while cloning env you can replace source-path/bin/pip freeze with source-path/bin/pip freeze --local, more about --local here

Hemant Malik
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0

Can you not simply:

  • Copy the existing virtual env directory to a new one
  • Update to the new Django?
Spacedman
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    Some times I use this approach, but has the inconvenience of having to update some paths inside the bin/activate script. – Armando Pérez Marqués Sep 16 '11 at 15:57
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    Is the change a simple find and replace on references to the env name, or is it more complicated than that? – Greg Aug 03 '12 at 03:24
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    In my case, simply updating the path in the VIRTUAL_ENV constant in bin/activate did the trick – bryanph Jun 18 '15 at 09:48
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    On the other hand, changing bin/activate is quite a hack, and one must wonder if this can break stuff at some point. Especially when virtual environments are used in production settings. – Herbert Apr 25 '16 at 10:41
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    It does break a lot of things. It's easier to just recreate or clone the virtualenv. I tried to do just this (while waiting for a proxy server to open up so that I can reinstall all required packages and just start from scratch), and it ain't working! I thought I was being clever, but alas, it will take a lot of hacking to get this up and running, and honestly, there are much better things to do. – horcle_buzz Jul 07 '16 at 18:53
  • @minghua Your edit adds a lot to the answer, I suggest adding a separate answer instead of the edit. – Ajay Brahmakshatriya May 16 '17 at 05:52
  • This has indexing issues with the python environment that you are trying to setup on the server. When you just copy paste virtualenv directory directly onto your required system, some files in the Include folder have absolute paths to bind different components, and now because that changes on your new system. So though you will be able to activate this new env but not use its packages. – Yashash Gaurav Sep 28 '18 at 06:19
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    It is not just the bin/activate that needs to be fixed. Look at the shabangs of the other scripts in bin/. They point to the original venv's python path. I would use the answer from @rdegges and freeze. – sqqqrly Nov 13 '19 at 20:59