The Cargo Book

First Steps with Cargo

This section provides a quick sense for the cargo command line tool. We demonstrate its ability to generate a new package for us, its ability to compile the crate within the package, and its ability to run the resulting program.

To start a new package with Cargo, use cargo new:

$ cargo new hello_world

Cargo defaults to --bin to make a binary program. To make a library, we would pass --lib, instead.

Let’s check out what Cargo has generated for us:

$ cd hello_world
$ tree .
.
├── Cargo.toml
└── src
    └── main.rs

1 directory, 2 files

This is all we need to get started. First, let’s check out Cargo.toml:

[package]
name = "hello_world"
version = "0.1.0"
edition = "2021"

[dependencies]

This is called a manifest, and it contains all of the metadata that Cargo needs to compile your package.

Here’s what’s in src/main.rs:

fn main() {
    println!("Hello, world!");
}

Cargo generated a “hello world” program for us, otherwise known as a binary crate. Let’s compile it:

$ cargo build
   Compiling hello_world v0.1.0 (file:///path/to/package/hello_world)

And then run it:

$ ./target/debug/hello_world
Hello, world!

We can also use cargo run to compile and then run it, all in one step:

$ cargo run
     Fresh hello_world v0.1.0 (file:///path/to/package/hello_world)
   Running `target/hello_world`
Hello, world!

Going further

For more details on using Cargo, check out the Cargo Guide