shpyx 0.0.7

Configurable shell command execution in Python

shpyX - Configurable shell command execution in Python

shpyX is a library which aims to simplify shell execution in Python by providing an API for easily interacting with the shell return code, outputs (i.e. stdio/stderr) and subprocess.

For example, suppose we want to run the following command:

cmd arg_1 arg_2

Suppose we also want to suppress all outputs if the command returns 0 and to raise a Python exception if the return code is not 0. With shpyX, we can do all that with:

import shpyx
shpyx.run("cmd arg_1 arg_2")

Installation

Install with pip:

pip install shpyx

Usage

Run a command:

>>> import shpyx
>>> shpyx.run("echo 'Hello world'")
ShellCmdResult(cmd="echo 'Hello world'", stdout='Hello world\n', stderr='', all_output='Hello world\n', return_code=0)

Run a command and print the output:

>>> shpyx.run("echo 'Hello world'", log_output=True)
Hello world
ShellCmdResult(cmd="echo 'Hello world'", stdout='Hello world\n', stderr='', all_output='Hello world\n', return_code=0)

Get live output during a long command:

>>> result = shpyx.run("echo 'Hello'; sleep 10000", log_output=True)
Hello

Motivation

I've been writing automation scripts for many years, mostly in Bash and Windows shell.

I love writing shell scripts, but in my opinion they become really hard to maintain once they become too big. I find Python a much more pleasant environment for doing the following things than a bare shell:

1. String/list manipulation
2. Error handling
3. Flow control (loops and conditions)
4. Output piping and manipulation

A few years ago I found out that the Python standard library provides a simple way of doing so via the subprocess module:

import subprocess

cmd = "ls -l"
p = subprocess.Popen([cmd], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
cmd_stdout, cmd_stderr = p.communicate()

I started with a simple function, which was used by my team, and over time encountered more and more requirements like:

• Inspect the return code
• See live command output (while it is being run)
• Gracefully handle commands that are stuck (due to blocking I/O, for example)
• Add formatted printing of every executed command and/or its output

The function gradually turned into a module which eventually turned into shpyX.

The goal of this project is to provide a friendly API for running shell commands, with emphasis on simplicity and configurability.

Security

The call to subprocess.Popen in this library uses shell=True which means that an actual system shell is being created, and the subprocess has the permissions of the main Python process.

It is therefore not recommended running untrusted commands via shpyX.

For more info, see security considerations.

Contributing

Running the linters:

docker-compose up --build linters