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translating---geekpi
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Why I love Xonsh
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======
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Shell languages are useful for interactive use. But this optimization often comes with trade-offs against using them as programming languages, which is sometimes felt when writing shell scripts.
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What if your shell also understood a more scalable programming language? Say, Python?
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Enter [Xonsh][1].
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Installing Xonsh is as simple as creating a virtual environment, running `pip install xonsh[ptk,linux]`, and then running `xonsh`.
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At first, you might wonder why your Python shell has a weird prompt:
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```
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$ 1+1
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2
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```
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Nice calculator!
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```
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$ print("hello world")
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hello world
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```
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We can also call other functions:
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```
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$ from antigravity import geohash
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$ geohash(37.421542, -122.085589, b'2005-05-26-10458.68')
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37.857713 -122.544543
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```
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However, we can still use it like a regular shell:
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```
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$ echo "hello world"
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hello world
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```
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We can even mix and match!
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```
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$ for i in range(3):
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. echo "hello world"
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.
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hello world
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hello world
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hello world
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```
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Xonsh supports completion for both shell commands and Python expressions by using the [Prompt Toolkit][2]. Completions are visually informative, showing possible completions and having in-band dropdown lists.
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It also supports environment access. It uses a simple but powerful heuristic for applying Python types to environment variables. The default is "string," but, for example, path variables are automatically lists.
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```
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$ '/usr/bin' in $PATH
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True
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```
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Xonsh accepts either shell-style or Python-style boolean shortcut operators:
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```
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$ cat things
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foo
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$ grep -q foo things and echo "found"
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found
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$ grep -q bar things && echo "found"
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$ grep -q foo things or echo "found"
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$ grep -q bar things || echo "found"
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found
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```
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This means that Python keywords are interpreted. If we want to print the title of a famous Dr. Seuss book, we need to quote the keywords.
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```
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$ echo green eggs "and" ham
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green eggs and ham
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```
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If we do not, we are in for a surprise:
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```
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$ echo green eggs and ham
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green eggs
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xonsh: For full traceback set: $XONSH_SHOW_TRACEBACK = True
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xonsh: subprocess mode: command not found: ham
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Did you mean one of the following?
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as: Command (/usr/bin/as)
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ht: Command (/usr/bin/ht)
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mag: Command (/usr/bin/mag)
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ar: Command (/usr/bin/ar)
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nm: Command (/usr/bin/nm)
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```
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Virtual environments can get a little tricky. Regular virtual environments, depending as they do on Bash-like syntax, cannot work. However, Xonsh comes with its own virtual environment management system called `vox`.
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`vox` can create, activate and deactivate environments in `~/.virtualenvs`; if you've used `virtualenvwrapper`, this is where the environments were.
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Note that the current activated environment doesn't affect `x``onsh`. It can't import anything from an activated environment.
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```
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$ xontrib load vox
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$ vox create my-environment
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...
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$ vox activate my-environment
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Activated "my-environment".
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$ pip install money
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...
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$ python
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...
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>>> import money
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>>> money.Money('3.14')
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$ import money
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xonsh: For full traceback set: $XONSH_SHOW_TRACEBACK = True
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ModuleNotFoundError: No module named 'money'
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```
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The first line enables `vox`: it is a `xontrib`, a third-party extension for Xonsh. The `xontrib` manager can list all possible `xontribs` and their current state (installed, loaded, or neither).
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It's possible to write a `xontrib` and just upload it to `PyPi` to make it available. However, it's good practice to add it to the `xontrib` index so Xonsh knows about it in advance. This allows, for example, the configuration wizard to suggest it.
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If you've ever wondered, "can Python be my shell?" then you are only a `pip install xonsh` away from finding out.
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/18/9/xonsh-bash-alternative
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作者：[Moshe Zadka][a]
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选题：[lujun9972](https://github.com/lujun9972)
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://opensource.com/users/moshez
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[1]: https://xon.sh/
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[2]: https://python-prompt-toolkit.readthedocs.io/en/master/
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translated/tech/20180904 Why I love Xonsh.md
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130
translated/tech/20180904 Why I love Xonsh.md
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@ -0,0 +1,130 @@
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我为什么喜欢 Xonsh
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======
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Shell 语言对交互式使用很有用。但是在使用它们作为编程语言时这种优化需要权衡，这有时在编写 shell 脚本时会感觉到。
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如果你的 shell 时一种更可伸缩的语言会怎样？比如说，Python？
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进入 [Xonsh][1]。
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安装 Xonsh 就像创建虚拟环境一样简单，运行 `pip install xonsh [ptk，linux]`，然后运行 `xonsh`。
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首先，你可能想知道为什么你的 Python shell 有一个奇怪的提示：
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```
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$ 1+1
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2
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```
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好的计算器！
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```
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$ print("hello world")
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hello world
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```
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我们还可以调用其他函数：
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```
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$ from antigravity import geohash
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$ geohash(37.421542, -122.085589, b'2005-05-26-10458.68')
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37.857713 -122.544543
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```
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然而，我们仍然可以像常规 shell 一样使用它：
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```
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$ echo "hello world"
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hello world
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```
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我们甚至可以混搭！
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```
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$ for i in range(3):
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. echo "hello world"
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.
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hello world
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hello world
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hello world
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```
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Xonsh 支持使用 [Prompt Toolkit][2] 补全 shell 命令和 Python 表达式。补全有可视化提示，会显示可能的补全并有下拉列表。
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它还支持访问环境变量。它使用简单但强大的启发式方法将 Python 类型应用于环境变量。默认值为 “string”，但是，例如，路径变量是自动列表。
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```
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$ '/usr/bin' in $PATH
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True
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```
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Xonsh 接受 shell 形式或 Python 形式的布尔快捷运算符：
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```
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$ cat things
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foo
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$ grep -q foo things and echo "found"
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found
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$ grep -q bar things && echo "found"
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$ grep -q foo things or echo "found"
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$ grep -q bar things || echo "found"
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found
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```
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这意味着 Python 关键字是被解释了。如果我们想要打印著名的 Dr. Seuss 书的标题，我们需要引用关键词。
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```
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$ echo green eggs "and" ham
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green eggs and ham
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```
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如果我们不这样做，我们会感到惊讶：
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```
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$ echo green eggs and ham
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green eggs
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xonsh: For full traceback set: $XONSH_SHOW_TRACEBACK = True
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xonsh: subprocess mode: command not found: ham
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Did you mean one of the following?
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as: Command (/usr/bin/as)
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ht: Command (/usr/bin/ht)
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mag: Command (/usr/bin/mag)
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ar: Command (/usr/bin/ar)
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nm: Command (/usr/bin/nm)
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```
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虚拟环境可能会有点棘手。一般的虚拟环境（取决于它们类似 Bash 的语法）无法工作。但是，Xonsh 自带了一个名为 `vox` 的虚拟环境管理系统。
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`vox` 可以创建，激活和停用 `~/.virtualenvs` 中的环境。如果你用过 `virtualenvwrapper`，这就是环境变量所在的地方。
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请注意，当前激活的环境不会影响 `xonsh`。它无法从激活的环境中导入任何内容。
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```
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$ xontrib load vox
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$ vox create my-environment
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...
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$ vox activate my-environment
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Activated "my-environment".
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$ pip install money
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...
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$ python
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...
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>>> import money
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>>> money.Money('3.14')
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$ import money
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xonsh: For full traceback set: $XONSH_SHOW_TRACEBACK = True
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ModuleNotFoundError: No module named 'money'
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```
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第一行启用 `vox`：它是一个 `xontrib`，Xonsh 的一个第三方扩展。`xontrib` 管理器可以列出所有可能的 `xontribs` 及其当前状态（已安装，已加载或未加载）。
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可以编写一个 `xontrib` 并上传到 `PyPi` 以使其可用。但是，最好将它添加到 `xontrib` 索引中，以便 Xonsh 提前知道它。比如，这能让配置向导建议它。
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如果你曾经想过，“Python 可以成为我的 shell 吗？”，然后你只要 `pip install xonsh` 一下就能知道。
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/18/9/xonsh-bash-alternative
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作者：[Moshe Zadka][a]
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选题：[lujun9972](https://github.com/lujun9972)
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译者：[geekpi](https://github.com/geekpi)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://opensource.com/users/moshez
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[1]: https://xon.sh/
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[2]: https://python-prompt-toolkit.readthedocs.io/en/master/
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