{"id":119,"date":"2017-04-05T18:55:03","date_gmt":"2017-04-05T21:55:03","guid":{"rendered":"https:\/\/www.linuxpro.com.br\/2017\/04\/hello-world\/"},"modified":"2026-09-08T11:21:59","modified_gmt":"2026-09-08T14:21:59","slug":"hello-world","status":"publish","type":"post","link":"https:\/\/www.linuxpro.com.br\/en\/2017\/04\/hello-world\/","title":{"rendered":"Hello World in Rust: installing and running on Ubuntu"},"content":{"rendered":"

\"Mascote<\/p>\n

Everyone starts with a Hello, world!<\/code>. This post uses that three-line program as an excuse to install Rust<\/strong> properly on Ubuntu, understand what cargo<\/code> does, and leave with a project that compiles \u2014 in about ten minutes.<\/p>\n

Why Rust, in two sentences<\/h2>\n

Rust delivers C performance without a garbage collector while eliminating, at compile time, the class of bugs that produces the most CVEs in systems software: use-after-free, buffer overflows, and thread races. The price is a compiler that argues with you during the first week.<\/p>\n

It is not a niche language: the Linux kernel removed Rust's experimental label in version 7.0, in April 2026, and Ubuntu 26.04 LTS already ships sudo<\/code> and core utilities rewritten in it. The full story is in The history of the Rust language<\/a>.<\/p>\n

Installing with rustup<\/h2>\n

Do not use apt install rustc<\/code>. Rust releases every six weeks and the distro package gets old quickly \u2014 besides not providing rustup<\/code>, which manages versions. The official approach:<\/p>\n

sudo apt update\nsudo apt install -y build-essential curl    # o Rust usa o linker do GCC\n\ncurl --proto '=https' --tlsv1.2 -sSf https:\/\/sh.rustup.rs | sh<\/code><\/pre>\n
Accept the default installation (option 1). When it finishes, load the environment in the current session \u2014 in subsequent sessions it loads automatically through ~\/.bashrc<\/code>:<\/p>\n
source \"$HOME\/.cargo\/env\"\n\nrustc --version\ncargo --version<\/code><\/pre>\n
You should see something like rustc 1.98.1<\/code>. If the command is not found, it is because ~\/.cargo\/bin<\/code> was not added to PATH<\/code> \u2014 the source<\/code> above fixes it.<\/p>\n
The first program, by hand<\/h2>\n
Before cargo<\/code>, it is worth seeing the bare compiler. Create ola.rs<\/code>:<\/p>\n
fn main() {\n    println!(\"Ol\u00e1, mundo!\");\n}<\/code><\/pre>\n
rustc ola.rs\n.\/ola<\/code><\/pre>\n
Two things to notice. rustc<\/code> generated a native binary<\/strong> \u2014 no VM, no interpreter, no runtime to install on the target machine. And println!<\/code> has an exclamation mark: in Rust, that means it is a macro<\/em>, not an ordinary function. You will see that exclamation mark often.<\/p>\n
Now the right way: cargo<\/h2>\n
In practice, nobody invokes rustc<\/code> manually. cargo<\/strong> is the project, dependency, and build manager \u2014 equivalent to what npm<\/code>, pip<\/code> and make<\/code> do together in other languages.<\/p>\n
cargo new ola\ncd ola\ncargo run<\/code><\/pre>\n
It creates the structure, compiles, and runs. What appeared:<\/p>\n
ola\/\n\u251c\u2500\u2500 Cargo.toml      # nome, vers\u00e3o, depend\u00eancias\n\u251c\u2500\u2500 .gitignore      # j\u00e1 vem pronto\n\u2514\u2500\u2500 src\/\n    \u2514\u2500\u2500 main.rs     # o seu c\u00f3digo<\/code><\/pre>\n
The commands you will use every day:<\/p>\n
cargo run                 # compila e executa\ncargo build               # s\u00f3 compila (bin\u00e1rio em target\/debug\/)\ncargo build --release     # compila otimizado \u2014 bem mais lento, bem mais r\u00e1pido\ncargo check               # verifica se compila, SEM gerar bin\u00e1rio (o mais r\u00e1pido)\ncargo test                # roda os testes\ncargo fmt                 # formata o c\u00f3digo no padr\u00e3o da comunidade\ncargo clippy              # o linter: pega o que compila mas \u00e9 m\u00e1 ideia<\/code><\/pre>\n
cargo check<\/code> is Rust's productivity secret: while you write, it responds in a fraction of the time taken by build<\/code>, because it does not generate machine code.<\/p>\n
If clippy<\/code> and fmt<\/code> are not installed:<\/p>\n
rustup component add clippy rustfmt<\/code><\/pre>\n
One step beyond \u201chello\u201d: reading input<\/h2>\n
A Hello, world!<\/code> does not show anything that makes the language different. This does \u2014 replace the contents of src\/main.rs<\/code>:<\/p>\n
use std::io::{self, Write};\n\nfn main() {\n    print!(\"Qual o seu nome? \");\n    io::stdout().flush().unwrap();\n\n    let mut nome = String::new();\n    io::stdin()\n        .read_line(&mut nome)\n        .expect(\"falha ao ler a entrada\");\n\n    let nome = nome.trim();\n\n    if nome.is_empty() {\n        println!(\"Voc\u00ea n\u00e3o digitou nada.\");\n    } else {\n        println!(\"Ol\u00e1, {nome}! Bem-vindo ao Rust.\");\n    }\n}<\/code><\/pre>\n
cargo run<\/code><\/pre>\n
Three details worth more than the program:<\/p>\n