chut 0.1

Small tool to interact with shell pipes

Chut is a small tool to help you to interact with shell pipes.

Basically it will help to write some shell script in python

This is more like a toy than a real tool but… it may be usefull sometimes.

Installation

$ pip install chut

Usage

Import the shell:

>>> from chut import ch

Then run what you want:

>>> print(ch.cat('/etc/passwd') | ch.grep('root') | ch.cut("-d: -f1"))
root

When I said what you want it’s mean that ch.whatyouwant will call a binary named whatyouwant

Let’s check if an error occured with whatyouwant:

>>> str(ch.whatyouwant()) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
OSError: whatyouwant

But an error can also occured if the binary exist:

>>> cmd = ch.cat('whatyouwant')
>>> output = str(cmd)
>>> print(cmd.returncodes)
[1]
>>> print(cmd.stderr)
cat: whatyouwant: No such file or directory

The pipe context manager

A context manager can help you to check for some errors:

>>> with ch.pipe(ch.cat('fff') | ch.grep('fff')) as p: # doctest: +ELLIPSIS
...    print(p)
Traceback (most recent call last):
...
OSError: cat: fff: No such file or directory

Use python !!

Finally you can use some python code ad the end of the pipe (and only at the end):

>>> @ch.wraps
... def check_root(stdin):
...     for line in stdin:
...         if line.startswith(b'root'):
...             yield b'User ' + line.split(b':', 1)[0] + b' exist\n'

>>> with ch.pipe(ch.cat('/etc/passwd') | check_root) as cmd:
...     for line in cmd:
...         print(line)
User root exist
<BLANKLINE>

Output

You can get the output as string:

>>> output = str(ch.cat('/etc/passwd') | check_root)

As an iterator (iter over each lines of the output):

>>> output = ch.cat('/etc/passwd') | check_root

And can use some redirection:

>>> ch.cat('/etc/passwd') | check_root > 'users.txt'
>>> print(ch.cat('users.txt'))
User root exist
>>> (ch.cat('/etc/passwd') | check_root) >> 'users.txt'
>>> print(ch.cat('users.txt'))
User root exist
User root exist

Parentheses are needed with >> only (due to the way the python operator work)

>>> with ch.pipe(ch.rm(' -f users.txt')) as cmd:
...     output = str(cmd)

Cheers.