arch-wiki-md-repo/wiki/_content/chinesesim/Python (chinesesim)-Virtual environment (简体中文).md

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**翻译状态：** 本文是英文页面 [Python/Virtualenv](/index.php/Python/Virtualenv "Python/Virtualenv") 的[翻译](/index.php/ArchWiki_Translation_Team_(%E7%AE%80%E4%BD%93%E4%B8%AD%E6%96%87) "ArchWiki Translation Team (简体中文)")，最后翻译时间：2017-10-19，点击[这里](https://wiki.archlinux.org/index.php?title=Python%2FVirtualenv&diff=0&oldid=492893)可以查看翻译后英文页面的改动。

*virtualenv* 是为 [Python](/index.php/Python "Python") 程序建立独立环境的工具，可以安装本地软件包，建立工作环境并在其中执行 [Python](/index.php/Python "Python")。

## Contents

*   [1 概览](#.E6.A6.82.E8.A7.88)
*   [2 安装](#.E5.AE.89.E8.A3.85)
*   [3 使用](#.E4.BD.BF.E7.94.A8)
    *   [3.1 创建虚拟环境](#.E5.88.9B.E5.BB.BA.E8.99.9A.E6.8B.9F.E7.8E.AF.E5.A2.83)
        *   [3.1.1 venv](#venv)
        *   [3.1.2 virtualenv](#virtualenv)
    *   [3.2 激活](#.E6.BF.80.E6.B4.BB)
*   [4 Python 版本](#Python_.E7.89.88.E6.9C.AC)
*   [5 virtualenvwrapper](#virtualenvwrapper)
    *   [5.1 Installation](#Installation)
    *   [5.2 Basic usage](#Basic_usage)
*   [6 See also](#See_also)

## 概览

虚拟环境是一个包含二进制程序和 shell 脚本的目录。二进制程序包含执行脚本的 *python* 和安装其它模块的 *pip*。脚本包括激活环境的脚本，[bash](/index.php/Bash "Bash"), csh 和[fish](/index.php/Fish "Fish") 个有一个。这个虚拟环境模拟了一个完整的 [Python](/index.php/Python "Python") 执行环境和需要的模块，将程序运行的环境与系统其它部分隔离开来。

## 安装

[Python](/index.php/Python "Python") 从 3.3 开始包含了 *venv* 程序，无需单独安装。 如果使用的是老版本的 Python, 需要额外[安装](/index.php/%E5%AE%89%E8%A3%85 "安装") *virtualenv*。

*   Python 3.3+: [python](https://www.archlinux.org/packages/?name=python)
*   Python 3: [python-virtualenv](https://www.archlinux.org/packages/?name=python-virtualenv)
*   Python 2: [python2-virtualenv](https://www.archlinux.org/packages/?name=python2-virtualenv)

## 使用

不同工具的使用方式基本相同。

### 创建虚拟环境

使用*venv* 或 *virtualenv* 在项目目录创建虚拟环境，请将 venv 目录加入版本控制系统，这样只要执行 `pip freeze` 就可以重建虚拟环境。

#### venv

**Note:** 此方法代替了从 [python](https://www.archlinux.org/packages/?name=python) 3.6 就不建议使用的 *pyvenv*。

[python](https://www.archlinux.org/packages/?name=python) 软件包从 3.3 开始就提供了此工具:

```
$ python -m venv venv

```

#### virtualenv

Python 3 使用 [python-virtualenv](https://www.archlinux.org/packages/?name=python-virtualenv) 提供的 *virtualenv*。

```
$ virtualenv venv

```

Python 2 使用 [python2-virtualenv](https://www.archlinux.org/packages/?name=python2-virtualenv) 提供的 *virtualenv2*。

```
$ virtualenv2 venv

```

### 激活

要激活虚拟环境(这里假设使用的是 bash):

```
$ source venv/bin/activate
(venv) $

```

一旦进入虚拟环境，就可以通过 *pip* 安装软件包，并正常执行脚本。

要退出寻环境，执行 `bin/activate` 下的:

```
(venv) $ deactivate

```

## Python 版本

二进制的版本由使用的虚拟环境工具决定。使用 Python 2 工具创建的虚拟环境中，*python* 命令指向 `bin/python2.7`，*venv* 创建的环境中， python 指向 `bin/python3.6`.

*venv* 和 *virtualenv* 差别在于 venv 默认使用系统的 Python 程序:

```
$ ls -l venv/bin/python3.6
lrwxrwxrwx 1 foo foo 7 Jun  3 19:57 venv/bin/python3.6 -> /usr/bin/python3

```

而 *virtualenv* 工具使用环境目录中的 Python 程序:

```
$ ls -l virtualenv/bin/python3.6
lrwxrwxrwx 1 foo foo 7 Jun  3 19:58 virtualenv/bin/python3.6 -> python3

```

## virtualenvwrapper

*virtualenvwrapper* allows more natural command line interaction with your virtual environemnts by exposing several useful commands to create, activate and remove virtual environments. This package is a wrapper for both [python-virtualenv](https://www.archlinux.org/packages/?name=python-virtualenv) and [python2-virtualenv](https://www.archlinux.org/packages/?name=python2-virtualenv).

### Installation

[Install](/index.php/Install "Install") the [python-virtualenvwrapper](https://www.archlinux.org/packages/?name=python-virtualenvwrapper) package from the [official repositories](/index.php/Official_repositories "Official repositories").

Now add the following lines to your `~/.bashrc`:

```
export WORKON_HOME=~/.virtualenvs
source /usr/bin/virtualenvwrapper.sh

```

Since python3 is a system-wide default in Arch, in order to be able to create python2 environments, you need to set `VIRTUALENVWRAPPER_PYTHON` and `VIRTUALENVWRAPPER_VIRTUALENV` prior to sourcing `virtualenvwrapper.sh` in your `~/.bashrc`:

```
export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python2.7
export VIRTUALENVWRAPPER_VIRTUALENV=/usr/bin/virtualenv2

```

The line `source /usr/bin/virtualenvwrapper.sh` can cause some slowdown when starting a new shell. To fix this try using `source /usr/bin/virtualenvwrapper_lazy.sh`, which will load virtualenvwrapper the first time a virtualenvwrapper function is called.

If you are not using python3 by default (check the output of `python --version`) you need to add the following line to your `~/.bashrc` prior sourcing the `virtualenvwrapper.sh` script.

```
export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3

```

Re-open your console and create the `WORKON_HOME` folder:

```
$ mkdir $WORKON_HOME

```

**Note:** This seems to happen now automatically after re-open the console for the first time.

### Basic usage

The main information source on virtualenvwrapper usage (and extension capability) is Doug Hellmann's [page](http://www.doughellmann.com/docs/virtualenvwrapper/).

Create the virtual environment:

```
$ mkvirtualenv -p /usr/bin/python2.7 my_env

```

Activate the virtual environment:

```
$ workon my_env

```

Install some package inside the virtual environment (say, Django):

```
(my_env) $ pip install django

```

After you have done your things, leave the virtual environment:

```
(my_env) $ deactivate

```

## See also

*   [Python venv](https://docs.python.org/3/library/venv.html)
*   [virtualenv Pypi page](https://pypi.python.org/pypi/virtualenv)
*   [Tutorial for virtualenv](http://wiki.pylonshq.com/display/pylonscookbook/Using+a+Virtualenv+Sandbox)
*   [virtualenvwrapper page at Doug Hellmann's](http://www.doughellmann.com/docs/virtualenvwrapper/)