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133 lines
4.7 KiB
Markdown
133 lines
4.7 KiB
Markdown
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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