How to install virtual environment on ubuntu 16.04

install virtualenv ubuntu 16.04.md

How to install virtualenv:

Install pip first

sudo apt-get install python3-pip

Then install virtualenv using pip3

sudo pip3 install virtualenv 

Now create a virtual environment

virtualenv venv 

you can use any name insted of venv

You can also use a Python interpreter of your choice

virtualenv -p /usr/bin/python2.7 venv

Active your virtual environment:

source venv/bin/activate

Using fish shell:

source venv/bin/activate.fish

To deactivate:

deactivate

Create virtualenv using Python3

virtualenv -p python3 myenv

Instead of using virtualenv you can use this command in Python3

python3 -m venv myenv

add virtualevnwrapper

sudo apt-get install virtualenvwrapper

create new virtualenv

root@lab:/tmp#mkvirtualenv test3
New python executable in /root/.virtualenvs/test3/bin/python
Installing setuptools, pip, wheel...done.
(test3) root@lab:/tmp#

exit the env

(test3) root@lab:~/.virtualenvs# deactivate

check current env

root@lab:~# workon
test3
test4

go inside a env

root@lab:~# workon test3
(test3) root@lab:~# pip list

install new package under the env

(test3) root@lab:~# pip list
pip (9.0.1)
setuptools (36.6.0)
wheel (0.30.0)
(test3) root@lab:~# pip install requests
requests (2.18.4)
(test3) root@lab:~# pip uninstall requests
no more requests (2.18.4)

this will not impact other env eg, test4 still the same packages.