Ubuntu 18.04 install virtualenv and virtualenvwrapper

Install and configure virtualenv and virtualenvwrapper

1. Install virtualenv and virtualenvwrapper

   pip install virtualenv
   pip install virtualenvwrapper
   

2. Create folder

   mkdir $HOME/.virtualenvs
   

3. Add in ~/.bashrc

   export WORKON_HOME=$HOME/.virtualenvs
   export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3
   source /usr/local/bin/virtualenvwrapper.sh
   

   The location of virtualenvwrapper.sh depends on the situation. It may be in the \usr\local\binmiddle or ~/.local/binmiddle.
4. Activate the .bashrc file

   source .bashrc
   

Note: If ERROR: virtualenvwrapper could not find virtualenv in your path appears , you can ~/.bashrcadd PATH=$PATH:~/.local/binor PATH=$PATH:/usr/local/bin.

pip change source

Commonly used domestic sources

• Alibaba Cloud http://mirrors.aliyun.com/pypi/simple/
• University of Science and Technology of China https://pypi.mirrors.ustc.edu.cn/simple/
• Douban http://pypi.douban.com/simple/
• Tsinghua University https://pypi.tuna.tsinghua.edu.cn/simple/
• University of Science and Technology of China http://pypi.mirrors.ustc.edu.cn/simple/

How to modify the source

1. temporary use
   1. When using pip, add -iparameters to specify the pip source.
      For example:

      	pip install scrapy -i  http://mirrors.aliyun.com/pypi/simple/
      

2. Permanent modification
   1. create~/.pip/pip.conf
   2. Add the following content

      [global]
      index-url = https://pypi.tuna.tsinghua.edu.cn/simple
      

   3. Just save

Common commands for virtualenv

1. Create a virtual environment
   1. Based on python2

      mkvirtualenv <env_name>
      

   2. Based on python3

      mkvirtualenv -p python3 <env_name>
      

   Note: The creation of a virtual environment requires networking. After the creation is successful, it will automatically work on this virtual environment (env_name will appear before the command line prompt).
2. Exit the virtual environment

   deactivate
   

3. Delete virtual environment

   rmvirtualenv <env_name>
   

4. View all virtual environments

   workon
   

   or

   lsvirtualenv
   

5. Navigate to the directory of the currently active environment

   cdvirtualenv
   

6. Navigate to the site-packages directory of the currently active environment

   cdsitepackages
   

7. Display all contents in the site-packages directory

   lssitepackages
   

8. View the installed packages in the current environment

   pip list
   

   or

   pip freeze
   

9. Check which packages in the current environment need to be updated

   pip list --outdated
   

   or

   pip list -o
   

10. Upgrade the current environment package

    pip install -U package_name
    

    or

    pip install --upgrade package_name
    

11. Install the package online for the current environment (you can specify the package version by using "==", ">=", "<=", ">", "<")

    pip install package_name
    

    or

    pip install -r package_names.txt
    

12. Install the downloaded local installation package for the current environment

    pip install <目录>/<文件名>
    

13. Uninstall the package of the current environment

    pip uninstall package_name
    

    or

    pip uninstall -r package_names.txt
    

14. View the package directory

    pip show -f package_name
    

15. Search package

    pip search keywords
    

16. Download the package without installing

    pip install package_name -d <目录>
    

    or

    pip install -r package_names.txt -d <目录>
    

17. Package all packages of the current virtual environment

    pip freeze > package_names.txt