I've often been asked for suggestions for an appropriate first project in Rust, and I think that writing a version of a unix utility is a great choice, for a bunch of reasons!

• There is a diverse and colorful cast of characters to choose from that all provide an appropriate scope and difficulty level, such as:

• tree: Print a graphical representation tree in visual form

• strings: Extract plaintext strings from binary files

• wc: Count the lines, characters, and bytes in a file

• ls: List the contents of a directory

• nc: Read and write bytes to network sockets

• cal: Print a cute text calendar

• cat: Copy streams to stdout

• cut: Extract delimited fields from linewise text records

• sort: Sort lines

• uniq: Print only unique lines

• The existing implementation provided by your system serves as a specification, giving you an idea of how the tool works and whether or not your implementation has the same behavior.

• The core functionality of these utilities is very simple, allowing a learner to quickly build something useful. And, many have additional features, allowing a learner to add and build if they wish. ls is simple, but ls -l is quite the project!

• Many creative additions are possible, like colorful output, expressive configuration, and fun and useful new features.

• IO and error handling are often front-and-center when writing these utilities, which provides a great chance to get used to explicit error handling.

• structopt makes argument parsing a breeze. And, by leveraging the type system and custom-derive, it provides a nice example of a situation where Rust has enormous advantages over other languages, allowing you to do more with less code.

• Rust binaries are fast to load and run, so performance is on par with native C implementations, and often much better than implementations in slower languages.

• Rust binaries are self-contained, so packaging and distribution is manageable, so you can share your work with the world.

• It's fun to use utilities that you wrote in your day-to-day workflow!

• There are lots of fabulous examples of utilities in the rust ecosystem, like ripgrep, fd, bat, exa, and hexyl. (Damn, David Peter is a beast.)

• If you're teaching others, a simple utility like strings makes for a great demonstration of the basics of the language.

I think whether you start with the book or a project like this depends on the learner.

I much prefer to jump in and struggle mightily, so I started with a project like this (what eventually became just), but I think a lot of people might prefer to start with the book, or at least parts of the book.