clap/examples/08_SubCommands.rs

extern crate clap;

use clap::{App, Arg, SubCommand};

fn main() {

    // SubCommands function exactly like sub-Apps, because that's exactly what they are. Each
    // instance of a SubCommand can have it's own version, author(s), Args, and even it's own
    // subcommands.
    //
    // # Help and Version
    // Just like Apps, each subcommand will get it's own "help" and "version" flags automatically
    // generated. Also, like Apps, you can override "-V" or "-h" safely and still get "--help" and
    // "--version" auto generated.
    //
    // NOTE: If you specify a subcommand for your App, clap will also autogenerate a "help"
    // subcommand along with "-h" and "--help" (applies to sub-subcommands as well).
    //
    // Just like arg() and args(), subcommands can be specified one at a time via subcommand() or
    // multiple ones at once with a Vec<SubCommand> provided to subcommands().
    let matches = App::new("MyApp")
                        // Normal App and Arg configuration goes here...

                        // In the following example assume we wanted an application which
                        // supported an "add" subcommand, this "add" subcommand also took
                        // one positional argument of a file to add:
                        .subcommand(SubCommand::with_name("add")                        // The name we call argument with
                                                .about("Adds files to myapp")           // The message displayed in "myapp -h"
                                                                                        // or "myapp help"
                                                .version("0.1")                         // Subcommands can have independent version
                                                .author("Kevin K.")                     // And authors
                                                .arg(Arg::with_name("input")            // And their own arguments
                                                            .help("the file to add")
                                                            .index(1)
                                                            .required(true)))
                        .get_matches();

    // You can check if a subcommand was used like normal
    if matches.is_present("add") {
        println!("'myapp add' was run.");
    }

    // You can get the independent subcommand matches (which function exactly like App matches)
    if let Some(ref matches) = matches.subcommand_matches("add") {
        // Safe to use unwrap() because of the required() option
        println!("Adding file: {}", matches.value_of("input").unwrap());
    }

    // You can also match on a subcommand's name
    match matches.subcommand_name() {
        Some("add") => println!("'myapp add' was used"),
        None        => println!("No subcommand was used"),
        _           => println!("Some other subcommand was used"),
    }

    // Continued program logic goes here...
}