VIRTUALENV Create an isolated Python environment __python

virtualenvVirtualenv is a tool. Used to create an isolated python environment.
First, installation
# pip Install virtualenv

Ii. Creating a Python virtual environment
Command: virtualenv [virtual Environment name].
# virtualenv ENV1
After execution, a folder with the same name as the virtual environment is generated locally.

Use the--python parameter to specify the Python version of the virtual environment:
# virtualenv--python=/usr/local/python-2.7.8/bin/python2.7 ENV1

If you want to rely on a Third-party package for your system environment, you can use parameter--system-site-packages.
Alternatively, you can use the Virtualenvwrapper toggle Global sitepackages command to control whether the current environment uses global site-packages.
# virtualenv--system-site-packages ENV1

Third, start the virtual environment
Enter the virtual environment directory and start the virtual environment as follows:
[Root@com ~]# CD env1/
[root@com env1]# Source Bin/activate
(ENV1) [Root@com env1]# Python-v
Python 2.7.8

All modules in the future PIP installation will be installed in the virtual environment directory.

Four, exit the virtual environment
#deactivate

VirtualenvwrapperVirtualenvwrapper is a virtualenv extension tool that makes it easy to create, delete, replicate, and switch to different virtual environments.
1. Installation and Configuration
# pip Install Virtualenvwrapper
Create a folder that holds all virtual environments:
# mkdir ~/workspaces
Set the environment variable and add the following two lines to the ~/.BASHRC.
Export Workon_home=~/workspaces
source/usr/bin/virtualenvwrapper.sh #/usr/local/bin/virtualwrapper.sh)
To make the setting take effect:
# source ~/.BASHRC


2. Create a virtual Environment: mkvirtualenv [Virtual Environment name]
[Root@com ~]# mkvirtualenv ENV1
(ENV1) [Root@com ~]#

Mkvirtualenv can use virtualenv parameters, such as--python, to specify the Python version. When you create a virtual environment, you automatically switch to this virtual environment. The virtual Environment directory is in the Workon_home.
(ENV1) [root@com ~]# mkvirtualenv envpy3--python=python3
(ENVPY3) [Root@com ~]#

3. List Virtual environments: Lsvirtualenv-b
(ENV2) [Root@.com ~]# Lsvirtualenv-b
Env1
Env2
4. Switch virtual Environment: Workon [Virtual Environment name]
(ENV2) [Root@com ~]# Workon ENV1
(ENV1) [Root@com ~]# Echo $VIRTUAL _env
/root/workspaces/env1

5. See what packages are installed in your environment: lssitepackages

6. Directory entering the current environment: cdvirtualenv [subdirectory name]
# cdvirtualenv
# pwd
/root/workspaces/env1sudo Easy_install Virtualenvwrapper
# Cdvirtualenv Bin
# pwd
/root/workspaces/env1/bin

Site-packages directory to enter the current environment: cdsitepackages [subdirectory name]
# cdsitepackages
# pwd
/root/workspaces/env1/lib/python2.6/site-packages
# cdsitepackages Pip
# pwd
/root/workspaces/env1/lib/python2.6/site-packages/pip
7. Control whether the environment uses global site-packages:toggleglobalsitepackages

8. Replication Virtual Environment: cpvirtualenv [Source] [dest]
# cpvirtualenv Env1 env3

9. Exit the virtual environment: deactivate
10. Delete Virtual Environment: rmvirtualenv [Virtual Environment name]