1 use clap::{arg, command, value_parser}; 2 main()3fn main() { 4 let matches = command!() // requires `cargo` feature 5 .arg( 6 arg!(<PORT>) 7 .help("Network port to use") 8 .value_parser(value_parser!(u16).range(1..)), 9 ) 10 .get_matches(); 11 12 // Note, it's safe to call unwrap() because the arg is required 13 let port: u16 = *matches 14 .get_one::<u16>("PORT") 15 .expect("'PORT' is required and parsing will fail if its missing"); 16 println!("PORT = {}", port); 17 } 18