Shell scripts made simple ?

Inspired by Google's zx, but made much simpler and more accessible using Python.


Bash is cool, and it's extremely powerful when paired with linux coreutils and pipes. But apart from that, it's a whole another language to learn, and has a (comparatively) unintuitive syntax for things like conditionals and loops.

zxpy aims to supercharge bash by allowing you to write scripts in Python, but with native support for bash commands and pipes.

Let's use it to find all TODOs in one of my other projects, and format them into a table:

#! /usr/bin/env zxpy
todo_comments = ~"git grep -n TODO"
for todo in todo_comments.splitlines():
    filename, lineno, code = todo.split(':', 2)
    *_, comment = code.partition('TODO')
    print(f"{filename:40} on line {lineno:4}: {comment.lstrip(': ')}")

Running this, we get:

$ ./todo_check.py
README.md                                on line 154 : move this content somewhere more sensible.
instachat/lib/models/message.dart        on line 7   : rename to uuid
instachat/lib/models/update.dart         on line 13  : make int
instachat/lib/services/chat_service.dart on line 211 : error handling
server/api/api.go                        on line 94  : move these to /chat/@:address
server/api/user.go                       on line 80  : check for errors instead of relying on zero value

A larger, practical example

You can find a comparison between a practical-ish script written in bash and
zxpy in EXAMPLE.md


pip install zxpy

Basic Examples

Make a file script.py (The name and extension can be anything):

#! /usr/bin/env zxpy
~'echo Hello world!'

file_count = ~'ls -1 | wc -l'
print("file count is:", file_count)

And then run it:

$ chmod +x ./script.py

$ ./script.py
Hello world!
file count is: 3

Run >>> help('zx') in Python REPL to find out more ways to use zxpy.

A slightly more involved example: run_all_tests.py

#! /usr/bin/env zxpy
test_files = (~"find -name '*_test\.py'").splitlines()

for filename in test_files:
        print(f'Running {filename:.<50}', end='')
        output = ~f'python {filename}'  # variables in your shell commands :D
        assert output == ''
        print('Test passed!')
        print(f'Test failed.')


$ ./run_all_tests.py
Running ./tests/python_version_test.py....................Test failed.
Running ./tests/platform_test.py..........................Test passed!
Running ./tests/imports_test.py...........................Test passed!

More examples are in EXAMPLE.md, and in the examples folder.

stderr and return codes

To get stderr and return code information out of the shell command, there is an
alternative way of invoking the shell.

To use it, just use 3 variables on the
left side of your ~'...' shell string:

stdout, stderr, return_code = ~'echo hi'
print(stdout)       # hi
print(return_code)  # 0

More examples are in the examples folder.

Interactive mode

$ zxpy
zxpy shell
Python 3.8.5 (default, Jan 27 2021, 15:41:15)
[GCC 9.3.0]

>>> ~"ls | grep '\.py'"

Also works with path/to/python -m zx

It can also be used to start a zxpy session in an already running REPL.
Simply do:

>>> import zx; zx.install()

and zxpy should be enabled in the existing session.


To install from source, clone the repo, and do the following:

$ source ./venv/bin/activate  # Always use a virtualenv!
$ pip install -r requirements-dev.txt
Processing ./zxpy
Successfully installed zxpy-1.X.X
$ pytest ./tests  # runs tests