Shell Programming in Python Snake Shell

Create lightweight Raspberry Pi scripts with Xonsh, a Python shell that lets you write scripts in Python with Bash commands mixed in

- Brooke Metcalfe and Pete Metcalfe

For Raspberry Pi users, Xonsh [1] offers many opportunities to write some extremely lightweight scripts, with Python connecting to physical devices and Bash utilities accessing system and file resources.

In this article, we look at two lean Xonsh projects for the Raspberry Pi. The first program connects to a DHT11 temperature and humidity sensor and shows the results in a Bash dialog in just five lines. The second project calls the Bash top utility in a lean eight lines to show the Raspberry Pi idle time and user time on a 16x2 LCD screen.

Getting Started

Xonsh has two requirements: Python 3.8 or greater and a Bash shell. To install and run Xonsh on a Raspberry Pi, Ubuntu, or Debian system, enter:

sudo apt install xonsh
xonsh

When the Xonsh shell opens, the terminal label changes so you can see that you are working in Xonsh rather than a standard Bash shell (Figure 1). When the shell first starts up, two options are presented: xonfig tutorial, which opens a browser help window, and xonfig web, which allows users to tweek the xonsh shell configuration.

Within the Xonsh shell, you can enter both Bash and Python statements, such as:

$ # Mix Bash and Python Lines
$ echo "Time is:" $(date +%T) ; # Bash
Time is: 12:59:51
$ print("%d + %d = %d" % U
            (2,3,2+3)) ; # Python
2 + 3 = 5

Xonsh in the Terminal