Backend Developer
Build a CLI Tool in Rust — Fast, Safe, and Cross-Platform
Key Takeaway
The Rust skill helps you build high-performance CLI tools, systems software, and WebAssembly modules. Your agent generates idiomatic Rust with proper error handling, clap argument parsing, and cross-compilation setup.
The Problem
You need a CLI tool that:
- Runs fast (not "wait 2 seconds for Python to start")
- Works on Linux, macOS, and Windows (single binary, no runtime)
- Handles errors properly (not "panic at every edge case")
- Has good CLI UX (colored output, progress bars, subcommands)
Python/Node.js CLIs: easy to write, slow to start, require runtime installation. Go CLIs: fast, easy cross-compilation, but garbage collector pauses and larger binaries. Rust CLIs: fastest, smallest binary, zero runtime, but steep learning curve.
The Solution
The Rust skill generates production-quality Rust code with proper error handling (thiserror + anyhow), argument parsing (clap), and project structure.
The Process
View details
You: Create a Rust CLI tool that:
- Scans a directory for large files
- Filters by size threshold and file extension
- Outputs results as table or JSON
- Shows progress bar for large directory scans
- Cross-compiles to Linux, macOS, Windows
The agent generates a complete Cargo project:
rustShow code
use clap::Parser;
use indicatif::{ProgressBar, ProgressStyle};
use tabled::{Table, Tabled};
use walkdir::WalkDir;
#[derive(Parser)]
#[command(name = "filescan", about = "Find large files fast")]
struct Cli {
/// Directory to scan
#[arg(default_value = ".")]
path: String,
/// Minimum file size (e.g., 100MB, 1GB)
#[arg(short, long, default_value = "100MB")]
min_size: String,
/// Filter by extension (e.g., .log, .mp4)
#[arg(short, long)]
ext: Option<String>,
/// Output format
#[arg(short, long, default_value = "table")]
format: OutputFormat,
}
// ... complete implementation with error handling,
// progress bar, and formatted output
Plus Cargo.toml with dependencies, .github/workflows/release.yml for automated cross-compilation, and README.md with installation instructions.
Binary size comparison:
| Language | Binary Size | Cold Start | Runtime Required |
|---|---|---|---|
| Python | N/A (script) | 800ms | Python 3.x |
| Node.js | N/A (script) | 400ms | Node.js 20+ |
| Go | 8-12 MB | 5ms | None |
| Rust | 2-4 MB | 1ms | None |
Setup on MrChief
yamlShow code
skills:
- rust
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