Last week I implemented one of the most commonly used CLI utility in Linux- head(1) inspired by John Crickett's Build Your Own Head coding challenge.

As head supports only two options, parsing arguments was easier to handle using if-else (although I don't like it at all). I could've used any library to parse arguments and options, but I really want to implement my own library (I don't know how yet!).

Writing tests in shell scripts is very helpful (especially for CLI tools). The real power of tests comes into play at the time of refactoring. When I abstracted code related to reading files into FileReader class, I was afraid that I might've broken some previous feature, but to my surprise I ran the test suite and all passed.

It helped me in two ways:

1. I didn't had to test the working of all the combinations options and arguments by manually running the code every time I made a change.
2. Running test suite after every refactor, suggested exactly which tests failed, that I needed to take care of.

The challenge was fun, took me around 2-3 hours, revised some constructs of C++ like file handling(text and binary mode), classes and class methods, build system using Makefiles and shell scripting.