Command Line Arguments

use std::env;

fn main() {
    let args: Vec<String> = env::args().collect(); // Turn argument iterator into a vector
    println!("{:?}", args); // Prints the arguments along with the binary name

    // Convert first argument to i32
    let num: i32 = args[1].parse().unwrap();
}

Environmental Variables

use std::env;

fn debug() {
    let DEBUG = env::var("DEBUG").is_err();
}

Read File

use std::fs;

fn read_file(file_name: &str) -> String {
    fs::read_to_string(file_name)
        .expect("Failed to open file {}")
}

fn main() {
    let file_name = "file.txt";
    read_file(file_name);
}