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Preface
A Virtual Environment is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them. It solves the “Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keeps your global site-packages directory clean and manageable. For example, you can work on a project which requires Django 1.10 while also maintaining a project which requires Django 1.8.
virtualenv
virtualenv is a tool to create isolated Python environments. virtualenv creates a folder which contains all the necessary executables to use the packages that a Python project would need.
Basic Usage
1. Create a virtual environment for a project:
virtualenv my_project will create a folder in the current directory which will contain the Python executable files, and a copy of the pip library which you can use to install other packages. The name of the virtual environment (in this case, it was my_project) can be anything; omitting the name will place the files in the current directory instead.
This creates a copy of Python in whichever directory you ran the command in, placing it in a folder named my_project. You can also use the Python interpreter of your choice (like python2.7).
or change the interpreter globally with an env variable in ~/.bashrc:
2. To begin using the virtual environment, it needs to be activated:
The name of the current virtual environment will now appear on the left of the prompt (e.g. (my_project)Your-Computer:your_project UserName$) to let you know that it’s active. From now on, any package that you install using pip will be placed in the my_project folder, isolated from the global Python installation.
Install packages as usual, for example (requests):
3. If you are done working in the virtual environment for the moment, you can deactivate it:
This puts you back to the system’s default Python interpreter with all its installed libraries. To delete a virtual environment, just delete its folder. (In this case, it would be rm -rf my_project.) After a while, though, you might end up with a lot of virtual environments littered across your system, and its possible you’ll forget their names or where they were placed.
Other Notes
Running virtualenv with the option --no-site-packages will not include the packages that are installed globally. This can be useful for keeping the package list clean in case it needs to be accessed later. (This is the default behavior for virtualenv 1.7 and later.) In order to keep your environment consistent, it’s a good idea to “freeze” the current state of the environment packages. To do this, run
This will create a requirements.txt file, which contains a simple list of all the packages in the current environment, and their respective versions. You can see the list of installed packages without the requirements format using “pip list”. Later it will be easier for a different developer (or you, if you need to re-create the environment) to install the same packages using the same versions:
This can help ensure consistency across installations, across deployments, and across developers. Lastly, remember to exclude the virtual environment folder from source control by adding it to the ignore list.
virtualenvwrapper
virtualenvwrapper provides a set of commands which makes working with virtual environments much more pleasant. It also places all your virtual environments in one place. To install (make sure virtualenv is already installed):
(Full virtualenvwrapper install instructions.)
Basic Usage
1. Create a virtual environment:
This creates the my_project folder inside ~/Envs.
2. Work on a virtual environment:
Alternatively, you can make a project, which creates the virtual environment, and also a project directory inside $PROJECT_HOME, which is cd -ed into when you workon myproject.
virtualenvwrapper provides tab-completion on environment names. It really helps when you have a lot of environments and have trouble remembering their names.
workon also deactivates whatever environment you are currently in, so you can quickly switch between environments.
3. Deactivating is still the same:
4. To delete:
Other useful commands
Full list of virtualenvwrapper commands.
virtualenv-burrito
With virtualenv-burrito, you can have a working virtualenv + virtualenvwrapper environment in a single command.
autoenv
When you cd into a directory containing a .env, autoenv automagically activates the environment. Install it:
Supplement
* Python 3 Tutorial 第七堂（1）pip 與 venv
[Git 常見問題] error: The following untracked working tree files would be overwritten by merge
Source From Here 方案1： // x -----删除忽略文件已经对 git 来说不识别的文件 // d -----删除未被添加到 git 的路径中的文件 // f -----强制运行 # git clean -d -fx 方案2： 今天在服务器上 gi...
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