选题: Why I love Xonsh

sources/tech/20180904 Why I love Xonsh.md

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+Why I love Xonsh
+======
+
+![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/shelloff.png?itok=L8pjHXjW)
+
+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.
+
+What if your shell also understood a more scalable programming language? Say, Python?
+
+Enter [Xonsh][1].
+
+Installing Xonsh is as simple as creating a virtual environment, running `pip install xonsh[ptk,linux]`, and then running `xonsh`.
+
+At first, you might wonder why your Python shell has a weird prompt:
+```
+$ 1+1
+2
+```
+
+Nice calculator!
+```
+$ print("hello world")
+hello world
+```
+
+We can also call other functions:
+```
+$ from antigravity import geohash
+$ geohash(37.421542, -122.085589, b'2005-05-26-10458.68')
+37.857713 -122.544543
+```
+
+However, we can still use it like a regular shell:
+```
+$ echo "hello world"
+hello world
+```
+
+We can even mix and match!
+```
+$ for i in range(3):
+.     echo "hello world"
+.
+hello world
+hello world
+hello world
+```
+
+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.
+
+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.
+```
+$ '/usr/bin' in $PATH
+True
+```
+
+Xonsh accepts either shell-style or Python-style boolean shortcut operators:
+```
+$ cat things
+foo
+$ grep -q foo things and echo "found"
+found
+$ grep -q bar things && echo "found"
+$ grep -q foo things or echo "found"
+$ grep -q bar things || echo "found"
+found
+```
+
+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.
+```
+$ echo green eggs "and" ham
+green eggs and ham
+```
+
+If we do not, we are in for a surprise:
+```
+$ echo green eggs and ham
+green eggs
+xonsh: For full traceback set: $XONSH_SHOW_TRACEBACK = True
+xonsh: subprocess mode: command not found: ham
+Did you mean one of the following?
+    as:   Command (/usr/bin/as)
+    ht:   Command (/usr/bin/ht)
+    mag:  Command (/usr/bin/mag)
+    ar:   Command (/usr/bin/ar)
+    nm:   Command (/usr/bin/nm)
+```
+
+Virtual environments can get a little tricky. Regular virtual environments, depending as they do on Bash-like syntax, cannot work. However, Xonsh comes with its own virtual environment management system called `vox`.
+
+`vox` can create, activate and deactivate environments in `~/.virtualenvs`; if you've used `virtualenvwrapper`, this is where the environments were.
+
+Note that the current activated environment doesn't affect `x``onsh`. It can't import anything from an activated environment.
+```
+$ xontrib load vox
+$ vox create my-environment                                                    
+...
+$ vox activate my-environment        
+Activated "my-environment".                                                    
+$ pip install money                                                            
+...
+$ python                                                              
+...
+>>> import money                                                              
+>>> money.Money('3.14')                        
+$ import money
+xonsh: For full traceback set: $XONSH_SHOW_TRACEBACK = True
+ModuleNotFoundError: No module named 'money'
+```
+
+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).
+
+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.
+
+If you've ever wondered, "can Python be my shell?" then you are only a `pip install xonsh` away from finding out.
+
+--------------------------------------------------------------------------------
+
+via: https://opensource.com/article/18/9/xonsh-bash-alternative
+
+作者：[Moshe Zadka][a]
+选题：[lujun9972](https://github.com/lujun9972)
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://opensource.com/users/moshez
+[1]: https://xon.sh/
+[2]: https://python-prompt-toolkit.readthedocs.io/en/master/