Install a python version using:
$ pyenv install 3.8.9
Installed Python-3.8.9 to /Users/robino/.pyenv/versions/3.8.9
List the python versions now available:
$ pyenv versions
* system
3.8.2
3.8.9
A week goes by and I forget where it is installed. Now suppose I want to get the executable path for 3.8.9 version. The following do not work:
$ pyenv which 3.8.9
pyenv: 3.8.9: command not found
$ pyenv which python 3.8.9
(gives path to system python)
$ pyenv which python-3.8.9
pyenv: python-3.8.9: command not found
$ pyenv which Python-3.8.9
pyenv: Python-3.8.9: command not found
A workaround I found was to set the python version, check, then set it back to system:
$ pyenv local 3.8.9
$ pyenv which python
/Users/robino/.pyenv/versions/3.8.9/bin/python
$ pyenv local --unset
However this is a suboptimal solution as it required that no local is previous set.
What is the correct command to print out the python executable path for a currently not used version, using pyenv?
By default, pyenv executable can be found at $(pyenv root)/versions/{VERSION}/bin/python. I am not aware of a command displaying all/any executables other than pyenv which python.
If you'd like to get the path via commands though, another option would be to make a temporary subdirectory and set the local pyenv interpreter there:
$ mkdir tmp; cd tmp
$ pyenv local 3.8.9
$ pyenv which python
/Users/robino/.pyenv/versions/3.8.9/bin/python
$ cd ..; rm -r tmp
Since deeper directories take priority with local pyenv versions, a parent directory wouldn't interfere in this case.
Yet another option would be to temporarily set the global pyenv version, as this does not have the requirement of no local pyenv version being set. I wouldn't like this though as I'd probably forget to set it back to its original value ;)
I simplified it a little, and the command runs in a subcommand, should be immune to side effect.
echo $(pyenv shell 3.9.15; pyenv which python)
# /Users/tomy0000000/.pyenv/versions/3.9.15/bin/python
This question already has answers here:
Dealing with multiple Python versions and PIP?
(28 answers)
Closed 1 year ago.
I have python 3.7.8 and python 3.10.0 installed. I have a question regarding the dependencies of these two. Is it okay to have this two installed at the same time but in different versions?
Does it make my site-packages conflict with one another?
On my command prompt, when I check my python version it says I am using the recent version, 3.10.0.
Having multiple versions on the same machine is perfectly "okay", as long as you understand how to select/use the correct python version, which is the more pertinent and useful question you should be asking yourself.
They would normally be installed in separate locations and would have separate site-packages (from How do I find the location of my Python site-packages directory?):
~$ python3.7 -c 'import site; print(site.getsitepackages())'
['/usr/local/Cellar/python#3.7/3.7.12_1/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages']
~$ python3.8 -c 'import site; print(site.getsitepackages())'
['/usr/local/Cellar/python#3.8/3.8.12_1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages']
~$ python3.9 -c 'import site; print(site.getsitepackages())'
['/usr/local/Cellar/python#3.9/3.9.9/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages']
The recommended way however is to not install to these site-packages folder directly and use a virtual environment instead. There are many variations of virtual env packages/tools, but you can start with the Python docs on Virtual Environments if you are not familiar or using one yet.
With virtual environments, you can usually indicate which version of python to use when creating the virtual env, so that whenever you activate that same env, it would use the same version you used to create it.
tmp$ python3.7 -m venv app1
tmp$ source ./app1/bin/activate
(app1) tmp$ python -V
Python 3.7.12
(app1) tmp$
(app1) tmp$ deactivate
tmp$ python3.8 -m venv app2
tmp$ source ./app2/bin/activate
(app2) tmp$ python -V
Python 3.8.12
(app2) tmp$
(app2) tmp$ deactivate
tmp$ python3.9 -m venv app3
tmp$ source ./app3/bin/activate
(app3) tmp$ python -V
Python 3.9.9
(app3) tmp$
(app3) tmp$ deactivate
In the above example, I created 3 virtual environments for 3 hypothetical apps, each using a different Python version. As long as I activate the correct virtual environment, I don't have to think about which version python refers to, as it will use the same version used to create the env. See also How do I check what version of Python is running my script?.
As for installing packages, again, once you have setup the correct virtual environments, doing pip install would ensure it installs only on the site-packages on that environment, and the app running on that env would be able to import that package.
If not using a virtual environment, as I noted in my comment, the answers at Dealing with multiple Python versions and PIP? provide good suggestions on how to ensure you are installing packages for the correct Python version, namely with
$ </path/or/alias/to/specific/python/installation> -m pip install <packages>
$ python3.7 -m pip install "flake8<=3.6"
$ python3.7 -m pip list | grep flake8
flake8 3.6.0
$ ls -H /usr/local/Cellar/python#3.7/3.7.12_1/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages | grep flake8
flake8
flake8-3.6.0.dist-info
flake8_quotes
flake8_quotes-3.2.0.dist-info
$ python3.9 -m pip install flake8
$ python3.9 -m pip list | grep flake8
flake8 4.0.1
$ ls -H /usr/local/Cellar/python#3.9/3.9.9/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages | grep flake8
flake8
flake8-4.0.1.dist-info
The above example shows 2 different versions of flake8 installed for 2 different versions of Python, each on their own site-packages folder.
But when I run my command prompt and check my python version it says I am using the recent version. The 3.10.0.
This means the system default for python or python3 on your machine points to the 3.10 installation. Mine is set to point to Python 3.9:
tmp$ python3 -V
Python 3.9.9
tmp$ which python3
/usr/local/bin/python3
tmp$ /usr/local/bin/python3 -V
Python 3.9.9
You can:
Manually change the default version
Setup aliases to the different versions:
tmp$ type python3.7
python3.7 is aliased to `/usr/local/opt/python#3.7/bin/python3'
tmp$ type python3.8
python3.8 is aliased to `/usr/local/opt/python#3.8/bin/python3'
tmp$ type python3.9
python3.9 is aliased to `/usr/local/opt/python#3.9/bin/python3'
Use a version management tool for switching versions, such as pyenv
To add onto Gino Mempin's answer it's also worth noting that in Windows you can quickly switch between versions of Python by editing the PATH environment variable in System Variables under your Environment Variables.
From my experience most people who switch between Python versions are on Linux but for all those people who might be using Windows you can just go to This PC -> Right-click -> Properties -> Advanced System Settings then from System Properties go to the Advanced tab and select Environment Variables to edit PATH. Note you don't have to delete older versions of Python here you can just add other ones and then select to move them above the others to give them priority.
You'll also need to restart your Command Prompt or Powershell after doing this if you had it open and was using Python before editing the environment variables.
After doing this you'll be able to install and manage packages for the current version of Python that has priority.
I'm working in Amazon's Cloud9.
ec2-user:~/environment/flask_init $ python -V
Python 2.7.14
ec2-user:~/environment/flask_init $ virtualenv -p python3 venv
Running virtualenv with interpreter /usr/bin/python3
Using base prefix '/usr'
New python executable in /home/ec2-user/environment/flask_init/venv/bin/python3
Also creating executable in /home/ec2-user/environment/flask_init/venv/bin/python
Installing setuptools, pip, wheel...done.
ec2-user:~/environment/flask_init $ source venv/bin/activate
(venv) ec2-user:~/environment/flask_init $ python -V
Python 2.7.14
Why is the virtual environment not using Python 3?
Please note that this question is not a duplicate of this one. The issue was specifically to do with the way the Cloud 9 environment sets up Python alias.
I tried your flow on my machine and everything works as expected.
dluzak#Karol-PC:/tmp$ python -V
Python 2.7.12
dluzak#Karol-PC:/tmp$ virtualenv -p python3 venv
Already using interpreter /usr/bin/python3
Using base prefix '/usr'
New python executable in /tmp/venv/bin/python3
Also creating executable in /tmp/venv/bin/python
Installing setuptools, pkg_resources, pip, wheel...done.
dluzak#Karol-PC:/tmp$ source venv/bin/activate
(venv) dluzak#Karol-PC:/tmp$ python -V
Python 3.5.2
(venv) dluzak#Karol-PC:/tmp$
Nonetheless I personally use virtualenv as module when creating venv with python 3: python3 -m virtualenv venv. Maybe this would work.
You provided very little details. Have you installed virtualenv for both Python 2 and 3? Are you sure Python 3 interpreter works fine?
Edit:
After investigation in comments we found out that the problem was in bash settings configured by Amazon. It seams that Amazon configures bash (probably in ~/.bashrc) to replace python calls with an alias. To fix this a call unalias python before enabling venv is needed. It is described in Amazon docs
When I was using virtualenv earlier today, I had the same problem that my env was not using the right version of python.
Instead of activating my environment like this:
source activate
I found that activating it like this actually worked:
source ./activate
Hope this is helpful!
Here is how i create virtualenv on Cloud9
Python 3.4
$ sudo pip install virtualenv
$ virtualenv -p /usr/bin/python3.4 venv
$ source venv/bin/activate
Python 3.6
$ sudo apt update
$ sudo apt install python3.6-venv
$ python3.6 -mvenv venv
$ source venv/bin/activate
I have encountered a similar issue.
In my case did not work because I moved the virtual env folder (but the same thing happens when you rename it).
You can understand which version of python (and thus which module will import) is using by typing
$ which python
If it write something like:
/usr/bin/python
Then it means your virtual env is not being activated.
To solve this issue, instead of creating a new virtual environment, you can simply edit the script activation file in your env:
$ nano venv/bin/activate
And edit the following line with your absolute path of your virtual environment:
VIRTUAL_ENV="/YOUR_ABSOLUT/PATH_TO/venv"
Hope it helps
:)
How do I create a virtual environment for a specified version of Python?
NOTE: For Python 3.3+, see The Aelfinn's answer below.
Use the --python (or short -p) option when creating a virtualenv instance to specify the Python executable you want to use, e.g.:
virtualenv --python="/usr/bin/python2.6" "/path/to/new/virtualenv/"
Since Python 3, the documentation suggests creating the virtual environment using:
python3 -m venv "my_env_name"
Also, if we want a particular version of python, lets say 3.6, then we can install as
python3.6 -m venv "my_env_name"
Make sure to install the referenced version of python along with your existing system python. For example, if the installed version in your system is python 3.8 only, you will encounter an error stating that "Command 'python3.6' not found".
Obsolete information
The pyvenv script can be used to create a virtual environment:
pyvenv "/path/to/new/virtual/environment"
Deprecated since Python 3.6.
These are the steps you can follow when you are on a shared hosting environment and need to install & compile Python from source and then create venv from your Python version. For Python 2.7.9. you would do something along these lines:
mkdir ~/src
wget http://www.python.org/ftp/python/2.7.9/Python-2.7.9.tgz
tar -zxvf Python-2.7.9.tgz
cd Python-2.7.9
mkdir ~/.localpython
./configure --prefix=$HOME/.localpython
make
make install
virtual env
cd ~/src
wget https://pypi.python.org/packages/5c/79/5dae7494b9f5ed061cff9a8ab8d6e1f02db352f3facf907d9eb614fb80e9/virtualenv-15.0.2.tar.gz#md5=0ed59863994daf1292827ffdbba80a63
tar -zxvf virtualenv-15.0.2.tar.gz
cd virtualenv-15.0.2/
~/.localpython/bin/python setup.py install
virtualenv ve -p $HOME/.localpython/bin/python2.7
source ve/bin/activate
Naturally, this can be applicable to any situation where you want to replicate the exact environment you work and deploy on.
There is an easier way,
virtualenv venv --python=python2.7
Thanks to a comment, this only works if you have python2.7 installed at the system level (e.g. /usr/bin/python2.7).
Otherwise, if you are using homebrew you can use the path to give you what you want.
virtualenv venv --python=/usr/local/bin/python
You can find the path to your python installation with which python (Linux) or py -0p (Windows)
This will also work with python 3.
which python3
>> /usr/local/bin/python3
virtualenv venv --python=/usr/local/bin/python3
Ultimately condensing to:
virtualenv venv -p `which python`
virtualenv venv -p `which python3`
virtualenv --python=/usr/bin/python2.6 <path/to/myvirtualenv>
Under Windows for me this works:
virtualenv --python=c:\Python25\python.exe envname
without the python.exe I got WindowsError: [Error 5] Access is denied
I have Python2.7.1 installed with virtualenv 1.6.1, and I wanted python 2.5.2.
Mac OSX 10.6.8 (Snow Leopard):
1) When you do pip install virtualenv, the pip command is associated with one of your python versions, and virtualenv gets installed into that version of python. You can do
$ which pip
to see what version of python that is. If you see something like:
$ which pip
/usr/local/bin/pip
then do:
$ ls -al /usr/local/bin/pip
lrwxrwxr-x 1 root admin 65 Apr 10 2015 /usr/local/bin/pip ->
../../../Library/Frameworks/Python.framework/Versions/2.7/bin/pip
You can see the python version in the output.
By default, that will be the version of python that is used for any new environment you create. However, you can specify any version of python installed on your computer to use inside a new environment with the -p flag:
$ virtualenv -p python3.2 my_env
Running virtualenv with interpreter /usr/local/bin/python3.2
New python executable in my_env/bin/python
Installing setuptools, pip...done.
virtualenv my_env will create a folder in the current directory which
will contain the Python executable files, and a copy of the pip
[command] which you can use to install other packages.
http://docs.python-guide.org/en/latest/dev/virtualenvs/
virtualenv just copies python from a location on your computer into the newly created my_env/bin/ directory.
2) The system python is in /usr/bin, while the various python versions I installed were, by default, installed into:
/usr/local/bin
3) The various pythons I installed have names like python2.7 or python3.2, and I can use those names rather than full paths.
========VIRTUALENVWRAPPER=========
1) I had some problems getting virtualenvwrapper to work. This is what I ended up putting in ~/.bash_profile:
export WORKON_HOME=$HOME/.virtualenvs
export PROJECT_HOME=$HOME/django_projects #Not very important -- mkproject command uses this
#Added the following based on:
#http://stackoverflow.com/questions/19665327/virtualenvwrapper-installation-snow-leopard-python
export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python2.7
#source /usr/local/bin/virtualenvwrapper.sh
source /Library/Frameworks/Python.framework/Versions/2.7/bin/virtualenvwrapper.sh
2) The -p option works differently with virtualenvwrapper: I have to specify the full path to the python interpreter to be used in the new environment(when I do not want to use the default python version):
$ mkvirtualenv -p /usr/local/bin/python3.2 my_env
Running virtualenv with interpreter /usr/local/bin/python3
New python executable in my_env/bin/python
Installing setuptools, pip...done.
Usage: source deactivate
removes the 'bin' directory of the environment activated with 'source
activate' from PATH.
Unlike virtualenv, virtualenvwrapper will create the environment at the location specified by the $WORKON_HOME environment variable. That keeps all your environments in one place.
[November 2019] I needed to install a Python 3.7 environment (env) on my Python 3.8-based Arch Linux system. Python 3.7 was no longer on the system, so I could not downgrade Python, to install a package that I needed.
Furthermore, I wanted to use that package / Python 3.7 inside a virtual environment (venv). This is how I did it.
Download Python version source files:
I downloaded the Python 3.7.4 source files from
https://www.python.org/downloads/source/
to
/mnt/Vancouver/apps/python_versions/src/Python-3.7.4.tgz
I then extracted that archive (source files) to
/mnt/Vancouver/apps/python_versions/src/Python-3.7.4/
Installation:
[Note: in my system env, not a venv.]
cd /mnt/Vancouver/apps/python_versions/src/Python-3.7.4/
time ./configure ## 17 sec
time make ## 1 min 51 sec
time sudo make install ## 18 sec
time make clean ## 0.3 sec
Examine installed Python versions:
$ which python
/usr/bin/python
$ python --version
Python 3.8.0
$ which python3.7
/usr/local/bin/python3.7
$ python ## Python 3.8 [system / env]
Python 3.8.0 (default, Oct 23 2019, 18:51:26)
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
$ python3.7 ## newly-installed Python 3.7 package
Python 3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print(sys.version)
3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0]
>>>
$ python3.7 --version
Python 3.7.4
How to create a venv for a specific Python version:
https://docs.python.org/3/tutorial/venv.html
12.2. CREATING VIRTUAL ENVIRONMENTS
The module used to create and manage virtual environments is called venv. venv will usually install the most recent version of Python that you have available. If you have multiple versions of Python on your system, you can select a specific Python version by running python3 or whichever version you want.
To create a virtual environment, decide upon a directory where you want to place it, and run the venv module as a script with the directory path:
python3 -m venv tutorial-env
This will create the tutorial-env directory if it doesn’t exist, and also create directories inside it containing a copy of the Python interpreter, the standard library, and various supporting files.
...
Create Python 3.7 venv [on a Python 3.8 operating env / system]:
python3.7 -m venv ~/venv/py3.7 ## create Python 3.7-based venv
source ~/venv/py3.7/bin/activate ## activate that venv
deactivate ## deactivate that venv (when done, there)
Added to ~/.bashrc:
alias p37='echo " [Python 3.7 venv (source ~/venv/py3.7/bin/activate)]" && source ~/venv/py3.7/bin/activate'
Test Python 3.7 venv:
$ p37
[Python 3.7 venv (source ~/venv/py3.7/bin/activate)]
(py3.7)$ python --version
Python 3.7.4
(py3.7)$ python
Python 3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print(sys.version)
3.7.4 (default, Nov 20 2019, 11:36:53)
[GCC 9.2.0]
>>>
Suppose you currently have python 2.7 installed in your virtualenv. But want to make use of python3.2, You would have to update this with:
$ virtualenv --python=/usr/bin/python3.2 name_of_your_virtualenv
Then activate your virtualenv by:
$ source activate name_of_your_virtualenv
and then do: python --version in shell to check whether your version is now updated.
You should have that Python version installed. If you have it then basically,
With virtualenv,
virtualenv --python=python3.8 env/place/you/want/to/save/to
with venv
python3.8 -m venv env/place/you/want/to/save/to
The above examples are for python3.8, you can change it to have different versions of virtual environments given that they are installed in your computer.
These two commands should work fine.
virtualenv -p python2 myenv (For python2)
virtualenv -p python3 myenv (For python3)
You can call virtualenv with python version you want. For example:
python3 -m virtualenv venv
Or alternatively directly point to your virtualenv path. e.g. for windows:
c:\Python34\Scripts\virtualenv.exe venv
And by running:
venv/bin/python
Python 3.5.1 (v3.5.1:37a07cee5969, Dec 5 2015, 21:12:44)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
you can see the python version installed in virtual environment
The -p approach works well, but you do have to remember to use it every time. If your goal is to switch to a newer version of Python generally, that's a pain and can also lead to mistakes.
Your other option is to set an environment variable that does the same thing as -p. Set this via your ~/.bashrc file or wherever you manage environment variables for your login sessions:
export VIRTUALENV_PYTHON=/path/to/desired/version
Then virtualenv will use that any time you don't specify -p on the command line.
On the mac I use pyenv and virtualenvwrapper. I had to create a new virtualenv. You need homebrew which I'll assume you've installed if you're on a mac, but just for fun:
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew install pyenv
pyenv install 2.7.10
pyenv global 2.7.10
export PATH=/Users/{USERNAME}/.pyenv/versions/2.7.10/bin:$PATH
mkvirtualenv -p ~/.pyenv/versions/2.7.10/bin/python {virtual_env_name}
I also froze my requirements first so i could simply reinstall in the new virtualenv with:
pip install -r requirements.txt
Even easier, by using command substitution to find python2 for you:
virtualenv -p $(which python2) <path/to/new/virtualenv/>
Or when using virtualenvwrapper :
mkvirtualenv -p $(which python2) <env_name>
As already mentioned in multiple answers, using virtualenv is a clean solution. However a small pitfall that everyone should be aware of is that if an alias for python is set in bash_aliases like:
python=python3.6
this alias will also be used inside the virtual environment. So in this scenario running python -V inside the virtual env will always output 3.6 regardless of what interpreter is used to create the environment:
virtualenv venv --python=pythonX.X
For Mac(High Sierra), install the virtualenv on python3 and create a virtualenv for python2:
$ python3 -m pip install virtualenv
$ python3 -m virtualenv --python=python2 vp27
$ source vp27/bin/activate
(vp27)$ python --version
Python 2.7.14
These seem a little overcomplicated for Windows. If you're on Windows running python 3.3 or later, you can use the python launcher py to do this much more easily. Simply install the different python version, then run:
py -[my version] -m venv env
This will create a virtual environment called env in your current directory, using python [my version]. As an example:
py -3.7 -m venv env
./env/Scripts/activate
This creates a virtual environment called env using python3.7 and activates it. No paths or other complex stuff required.
I utilized this answer for Windows
https://stackoverflow.com/a/22793687/15435022
py -3.4 -m venv c:\path\to\wherever\you\want\it
On windows:
py -3.4x32 -m venv venv34
or
py -2.6.2 -m venv venv26
This uses the py launcher which will find the right python executable for you (assuming you have it installed).
In windows subsystem for linux:
Create environment for python3:
virtualenv --python=/usr/bin/python3 env
Activate it:
source env/bin/activate
I use pyenv to manage my python version.
pyenv install 3.7.3
pyenv local 3.7.3
Check your python version:
$ python --version
Python 3.7.3
Create the virtual environment with venv:
python -m venv .
Then activate the Virtual Environment:
source bin/activate
Check your python version:
$ python --version
Python 3.7.3
You may need to remove the previous virtual environment
rm -rf bin
End of 2020:
The most seamless experience for using virtualenv (added benefit: with any possible python version) would be to use pyenv and its (bundled) pyenv-virtualenv plugin (cf https://realpython.com/intro-to-pyenv/#virtual-environments-and-pyenv)
Usage: pyenv virtualenv <python_version> <environment_name>
Installation:
first check that you've got all prerequisites (depending on your OS): https://github.com/pyenv/pyenv/wiki/Common-build-problems#prerequisites
curl https://pyenv.run | bash
exec $SHELL
cf https://github.com/pyenv/pyenv-installer
That being said, nowadays the best possible alternative instead of using virtualenv (and pip) would be Poetry (along with pyenv indicated above, to handle different python versions).
Another option, because it's supported directly by the PyPA (the org behind pip and the PyPI) and has restarted releasing since the end of May (didn't release since late 2018 prior to that...) would be Pipenv
This worked for my usage in Windows 10, where I have Python 3.7 and want to downgrade for a project in Python 3.6.6:
I used "venv" to create a new environment called "venv", I downloaded from https://www.python.org/downloads/windows/ ; install "Download Windows x86-64 executable installer-" ; then I used the following command line in the directory where I want to create my environment
>C:\Users\...\Python\Python36\python.exe -m venv venv
Finally, I activated the environnent using the command line:
>venv\Scripts\activate.bat
And check the python version by calling:
>python --version
Python 3.6.6
On Linux Ubuntu 21.04 (currently Python 3.9.5) I needed to get a virtualenv of Python 3.7.8. Full steps to get working:
Find the Python version source you want, for example 3.7.8 is here: https://www.python.org/downloads/release/python-378/
Download the Gzipped source tarball
Unzip it with tar zxvf Python-3.7.8.tgz (amend as required with your version number if different from 3.7.8)
Copy the unzipped folder to /usr/bin with: sudo cp -r Python-3.7.8 /usr/bin
cd /usr/bin/Python-3.7.8/
Check the contents if you wanted to see what you have so far: ls
sudo time ./configure
sudo time make
time sudo make install
time make clean
Check how your python is set up and reporting:
which python
python --version
Should be all relating to your primary install (Python 3.9.5 for me)
To check your new install:
which python 3.7
python3.7 --version
Should be all relating to your 3.7.8 install
If you want to run it to check, do:
python3.7
exit()
Install venv:
sudo apt install venv
To create a venv (maybe in your repo, if so, add .venv to .gitignore):
python3.7 -m venv .venv
To activate your venv:
source .venv/bin/activate
Check your version:
python --version
Answer to this question shouldn't be that complicated...
TL,DR:
install as many versions of python you prefer on your system and use:
/c/path/to/any/version/of/python -m venv my_venv
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I use venv to install virtual environments with
python -m venv <where/to/and/name_of_venv>
if you try which python you will see which python you are referring to, when saying "python". for example, for me it is:
which python
result:
/c/Program Files/Python36/python
So, now you have the answer!
you can install any version of python on your system and have multiple of them at the same time. So, for example I installed Python3.7 in this directory: "C:\Program Files\Python37".
So, instead of using 'python' now I specify which python by /c/Program\ Files/Python37/python:
/c/Program\ Files/Python37/python -m venv my_venv
(don't forget to escape the space in the path)
That's it!
Yes, the above answers are correct and works fine on Unix based systems like Linux & MAC OS X.
I tried to create virtualenv for Python2 & Python3 with the following commands.
Here I have used venv2 & venv3 as their names for Python2 & Python3 respectively.
Python2 »
MacBook-Pro-2:~ admin$ virtualenv venv2 --python=`which python2`
Running virtualenv with interpreter /usr/local/bin/python2
New python executable in /Users/admin/venv2/bin/python
Installing setuptools, pip, wheel...done.
MacBook-Pro-2:~ admin$
MacBook-Pro-2:~ admin$ ls venv2/bin/
activate easy_install pip2.7 python2.7
activate.csh easy_install-2.7 python wheel
activate.fish pip python-config
activate_this.py pip2 python2
MacBook-Pro-2:~ admin$
Python3 »
MacBook-Pro-2:~ admin$ virtualenv venv3 --python=`which python3`
Running virtualenv with interpreter /usr/local/bin/python3
Using base prefix '/Library/Frameworks/Python.framework/Versions/3.6'
New python executable in /Users/admin/venv3/bin/python3
Also creating executable in /Users/admin/venv3/bin/python
Installing setuptools, pip, wheel...done.
MacBook-Pro-2:~ admin$
MacBook-Pro-2:~ admin$ ls venv3/bin/
activate easy_install pip3.6 python3.6
activate.csh easy_install-3.6 python wheel
activate.fish pip python-config
activate_this.py pip3 python3
MacBook-Pro-2:~ admin$
Checking Python installation locations
MacBook-Pro-2:~ admin$ which python2
/usr/local/bin/python2
MacBook-Pro-2:~ admin$
MacBook-Pro-2:~ admin$ which python3
/usr/local/bin/python3
MacBook-Pro-2:~ admin$
I use Windows so I should use .exe on the pthon path
virtualenv -p=C:\Python27\python2.exe <envname>
It worked for me
sudo apt-get install python3-minimal
virtualenv --no-site-packages --distribute -p /usr/bin/python3 ~/.virtualenvs/py3
virtualenv -p python3 myenv
Link to Creating virtualenv