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Error in installing venv for python3 on mac

While installing a virtual environment by running the following command on terminal:
python3 -m pip install --user venv
I'm encountering the following error:
ERROR: Could not find a version that satisfies the requirement venv
ERROR: No matching distribution found for venv
Please help me with this! I believe since default python is version 2.x in macOS I must try installing virtualenv but I require venv.

You cannot install venv with pip: venv is a module from the standard library since Python 3.3. So you don't need to install it, just start using:
python3 -m venv path/to/new-venv

Venv doesn't exists. I guess that you might want the package virtualenv.
Venv is commonly used as the name of virtual environment created by virtualenv.
So, the command is:
python3 -m pip install --user virtualenv
python3 -m virtualenv venv

How to force install package in virtualenv?

Trying to install django with different version that in system, it shows me:
Installing collected packages: Django
Found existing installation: Django 1.7.11
Not uninstalling django at /home/user/lib/python2.7, outside environment /home/user/webapps/v2_dev/venv
Successfully installed Django-1.8.19
But in fact there is old version
tried with different commands:
./venv/bin/pip install Django==1.8.11
pip install Django==1.8.11
UPDATED:
When I install my packages it shows:
The required version of setuptools (>=16.0) is not available,
and can't be installed while this script is running. Please
install a more recent version first, using
'easy_install -U setuptools'.
(Currently using setuptools 3.1 (/home/user/lib/python2.7/setuptools-3.1-py2.7.egg))
When I do the upgrade:
venv/bin/pip install --upgrade setuptools
Requirement already up-to-date: setuptools in ./venv/lib/python2.7/site-packages (40.5.0)

I arrived at this post while looking for how to force install something in a virtualenv despite it being already installed in the global python. This happens when the virtual env was created with --system-site-packages.
In this situation, for certain packages it may be important to have a local version within the virtualenv, even if for many other packages we can share the global versions. This is the case of pytest, for example. However, pip will refuse to install a package in the virtualenv if it can already find the most recent version in the system site.
The solution is to use pip install --ignore-installed mypackage.

Instead of installing setuptools and Django like ./venv/bin/pip install ..., try to activate your virtual environment first and install the stuff you need afterwards.
Activating virtual environment:
Go to the folder where your virtual environment is located (typically the root folder of your project) and type one of the two:
source venv/bin/activate (Unix-based systems)
venv\Scripts\activate (Windows)
This will ensure that you are not mixing packages installed in different environments.
Forcing reinstall of the packages:
Simple upgrade can be done by adding: --upgrade or -U
Forcing reinstall of the packages can be done by adding: --force-reinstall
In your case (once the environment is activated):
python -m pip install -U --force-reinstall setuptools Django
Step by step:
Deactivate and delete the old virtual environment
Create new environment using python -m virtualenv venv (python 2) or python -m venv venv (python 3)
python above is the interpreter which you want to use in your project. That's the only point where you might want to use for example python3 or some absolute path instead. Later use the code as is.
source venv/bin/activate
Activating the virtual environment
python -m pip install -U pip
If you have issue with ImportError: No module named _internal than probably you are using an old version of pip. Issue is described here
python -m pip install -U --force-reinstall -r requirements.txt
-U --force-reinstall is a bit of an overkill in case of fresh environment, but it will do no harm
Go to the place where your manage.py is located and start the server using python manage.py runserver

The problem was in Webfaction VPS
Need an empty file named sitecustomize.py in the /home/username/webapps/appName/env/lib/python2.
That empty file overrides their python customizations, one of which is to include any packages in the ~/lib/python2.7 directory.
You might need to deactivate your virtual env and activate it again for changes to take effect.

workaround but it works!
in your virtualenv directory change the properties of the pyvenv.cfg file
include-system-site-packages = True
this will cause the packages installed on the main to be used

Install Python 3.6.3 in Virtualenv using pip in WIndows 10?

How do you install Python 3.6.x in a virtualenv using pip in Windows 10?
pip install python, pip install python3, pip install python3.6 don't work.

Pip and virtualenv are two separate tools. Pip is a package manager, you will use it to install packages into your virtual environment once it has been set up. Pip does not actually manage the virtual environment. Virtualenv is the tool that handles creating virtual environments.
First, you should check if you have virtualenv installed with virtualenv --version. If you do not have it, you will get an error that virtualenv is not found. You can use pip to install virtualenv with pip install virtualenv.
Once you have virtualenv, you can create a python 3.6 environment with virtualenv -p python3.6 /path/to/myvirtualenv. You will need an installation of python 3.6 for this command to work, so download and install python 3.6 first if you do not have it.
I believe that on windows if you don't have python 3.6 in your PATH variable, you may need to point directly to the python 3.6 installation instead with virtualenv -p /path/to/mypython3.6 /path/to/myvirtualenv.
See Virtualenv User Guide

Python 3.5 install pyvenv

I am trying to get a virtual environment for a repo that requires python 3.5. I am using Debian, and from what I can tell, python 3.5 does not have an aptitude package. After reading some posts, it was recommended to download 3.5 source code and compile it.
After running the make and install, python3.5 was installed to /usr/local/bin. I added that to the $PATH variable.
Here is where I ran into problems. After I ran:
$ cd project-dir
$ pyvenv env
$ source env/bin/activate
$ pip install -r requirements.txt
I was getting issues with needing sudo to install the proper packages. I ran:
$ which pip
and it turns out that pip was still using the /usr/local/bin version of pip.
$ echo $PATH
returned
/home/me/project-dir/env/bin:/usr/local/bin:/usr/bin:/bin: ...
I am assuming that because the /usr/local path came after the virtual environment's path in my PATH variable, it is using that version of pip instead of my virtual environments.
What would be the best way to run the correct version of pip within the virtualenv? The two options I can think of is moving the binaries over to /usr/bin or modifying the activate script in my virtual env to place the virtualenv path after /usr/local.

Option 1
You can upgrade pip in a virtual environment manually by executing
pip install -U pip
Option 2
Good method to upgrade pip inside that package
python -m ensurepip --upgrade does indeed upgrade the pip version in the system (if it is lower than the version in ensurepip).
You are facing this problem, because venv uses ensurepip to add pip into new environments:
Unless the --without-pip option is given, ensurepip will be invoked to
bootstrap pip into the virtual environment.
Ensurepip package won't download from the internet or grab files from anywhere else, because all required components are already included into the package. Doing so would add security flaws and is thus unsupported.
Ensurepip is not designed to give you the newest pip, but just "a" pip. To get the newest one use the manual way at the beginning of this post.
To check ensurepip version you can type into python console import ensurepip print(ensurepip.version())
More Findings for further reading:
To upgrade ensurepip manually using files - https://github.com/python/cpython/commit/f649e9c44631c07e707842c42747b651b986dcc4
What's the proper way to install pip, virtualenv, and distribute for Python?
Comprehensive beginner's virtualenv tutorial?

Kesh's answer led me in the right direction.
The problem was that I didn't actually have pip installed in my venv.
It turns out, when I built python3.5 from source, I did not have the libssl-dev package. It looks like one of the dependencies of ensurepip was the python ssl package that didn't get installed because I didn't have libssl-dev.
To fix the problem, I rebuilt python 3.5 for source with the libssl-dev package installed. The rebuilt python now included the ssl package, which allowed ensurepip to install pip in my virtual environment.

Try installing it locally:
pip install --user -r requirements.txt
which would, I believe, install the file in a sub-directory of your $HOME directory (which your virtual env I would think would set). Otherwise I think you could just use:
/path/to/virtualenv/pip install -r requirements.txt

How do I can install pip inside virtual environment

I have created one virtual-environment. Inside that I have to install few python packages. For that I need pip package inside virtual environment. How can I install pip inside virtual-environment?

According to the pip documentation, you can install pip in a virtual environment by typing the following command when your virtual environment is activated:
python -m ensurepip --upgrade
For your information, ensurepip is an in-built Python module that serves the purpose of installing pip in your Python environment.

you can also try with upgrading pip command even after no pip installed at you specified virtual location
python -m pip install --upgrade pip
This will give you an error as below but also install latest pip version on virtual location
Can't uninstall 'pip'. No files were found to uninstall.
Successfully installed pip-19.2.3
kindly try above option and let me in case any issue.

Usually, you install pip OUTSIDE of your virtual environment.
But after activating the virtualenv you just run "pip install" inside the environment.
Meaning, you install it outside the virtualenv.
You run "pip install" inside the virtualenv.
You can follow this useful guide:
http://docs.python-guide.org/en/latest/dev/virtualenvs/

When you create a virtual environment for a particular python revision installed in your computer, all the libraries currently installed in your python revision would be copied inside the virtual environment.
Pip is usually default available in your python revision directory.
If not, install it first in your original python install directory.
Then copy the pip.exe to the virtual environment's Scripts directory.
After that execute the below command from your terminal (this is for Windows):
\your_venv_directory_path\Scripts\pip.exe install --upgrade pip
Now you can just type
pip install --upgrade pip
and it should recognise the path to the pip.exe file inside your venv

when creating the virtual-environment, be sure to include pip in the command. e.g:
conda create -n my_env pip python=3.6.8
I would suggest deleting the venv and recreating it using the above command