Build Your First Rust CLI Tool: A Beginner-Friendly Walkthrough

Command-line tools are a great way to automate tasks, process data, or even just have fun with small utilities. Rust is an excellent language for this because it compiles to fast, standalone binaries with no runtime dependency and offers strong safety guarantees. In this article, we’ll walk through building a simple CLI tool in Rust that reads a file and counts the number of words—similar to the Unix wc command. Step 1: Set Up Your Project Start by creating a new binary project: cargo new wordcount --bin cd wordcount This gives you a working Rust project with src/main.rs as your entry point. Step 2: Parse Command-Line Arguments To keep things simple, we'll use the built-in std::env module to fetch the file path from the command line: use std::env; use std::fs; fn main() { let args: Vec = env::args().collect(); if args.len() < 2 { eprintln!("Usage: wordcount "); std::process::exit(1); } let filename = &args[1]; let contents = fs::read_to_string(filename) .expect("Something went wrong reading the file"); let word_count = contents.split_whitespace().count(); println!("Word count: {}", word_count); } Step 3: Build and Test It Build the project: cargo build --release Try it out: ./target/release/wordcount sample.txt If everything works, you should see the number of words printed to the terminal. Use Case Scenario Imagine you're managing hundreds of text-based logs generated daily by a data pipeline. Manually reviewing them is inefficient. A fast CLI tool like this one can help you quickly analyze the logs—perhaps to find the lengthiest reports, flag empty files, or identify unusually verbose entries. With minimal setup, you can extend the tool to scan directories, summarize data, or even integrate into shell scripts. The result is better visibility into your data with significantly reduced manual effort—saving both time and cognitive load in your workflow. ✅ Pros and ❌ Cons of Using Rust for CLI Tools ✅ Pros: ⚡ Blazing fast binaries

May 12, 2025 - 06:41

Build Your First Rust CLI Tool: A Beginner-Friendly Walkthrough

Command-line tools are a great way to automate tasks, process data, or even just have fun with small utilities. Rust is an excellent language for this because it compiles to fast, standalone binaries with no runtime dependency and offers strong safety guarantees.

In this article, we’ll walk through building a simple CLI tool in Rust that reads a file and counts the number of words—similar to the Unix wc command.

Step 1: Set Up Your Project

Start by creating a new binary project:

cargo new wordcount --bin
cd wordcount

This gives you a working Rust project with src/main.rs as your entry point.

Step 2: Parse Command-Line Arguments

To keep things simple, we'll use the built-in std::env module to fetch the file path from the command line:

use std::env;
use std::fs;

fn main() {
    let args: Vec = env::args().collect();

    if args.len() &lt; 2 {
        eprintln!("Usage: wordcount ");
        std::process::exit(1);
    }

    let filename = &amp;args[1];
    let contents = fs::read_to_string(filename)
        .expect("Something went wrong reading the file");

    let word_count = contents.split_whitespace().count();
    println!("Word count: {}", word_count);
}

Step 3: Build and Test It

Build the project:

cargo build --release

Try it out:

./target/release/wordcount sample.txt

If everything works, you should see the number of words printed to the terminal.

Use Case Scenario

Imagine you're managing hundreds of text-based logs generated daily by a data pipeline. Manually reviewing them is inefficient. A fast CLI tool like this one can help you quickly analyze the logs—perhaps to find the lengthiest reports, flag empty files, or identify unusually verbose entries. With minimal setup, you can extend the tool to scan directories, summarize data, or even integrate into shell scripts. The result is better visibility into your data with significantly reduced manual effort—saving both time and cognitive load in your workflow.

✅ Pros and ❌ Cons of Using Rust for CLI Tools

✅ Pros:

⚡ Blazing fast binaries