use std::env;
use std::io;
use std::process;

fn main() {
    let args: Vec<String> = env::args().collect();
    //println!("{:?}", args);
    let to_grep = &args[1];
    if args.len()<2{
        process::exit(0x0100);
    }

    if &args[1]=="-h" {
        println!("GREP in Rust
            -h - this help");
        process::exit(0x0100);
    }

    loop{
    let mut piped = String::new();
    io::stdin().read_line(&mut piped)
        .expect("");
    if piped == "" { break; }
    if piped.contains(to_grep){
        print!("{}",piped);
    };
    }
}