coreutils/src/rs/cat.rs

// Copyright (c) 2022 Emma Tebibyte
// SPDX-License-Identifier: AGPL-3.0-or-later

use std::fs::read_to_string;
use std::io;
use std::io::Write;
use std::env;
use std::process;

fn main() {
  let mut args: Vec<String> = env::args().collect();
  let argv0 = args.remove(0);
  let mut opts = Vec::new();
  
  for arg in &args {
    if arg.starts_with("-") {
      opts.push(arg);
    }
  }

  if opts.is_empty() == false {
    for option in opts {
      match option.as_str() {
        // Write  bytes  from the input file to the standard output without
        // delay as each is read.
        "-u" => {},

        _ => {
          println!("Usage: {} [options...] [files...]", argv0);
          process::exit(64); // sysexits(3) EX_USAGE
        },
      };
    }
  }
  else { 
    for path in args {
      let mut val = String::new();

      match path.as_str() {
        "-" => {
          let mut content = String::new();
          match io::stdin().read_line(&mut content) {
            Ok(_) => { val.push_str(&content); },
            Err(_) => {
              println!("Usage: {} [options...] [files...]", argv0);
              process::exit(64); // sysexits(3) EX_USAGE
            },
          };
        },

        _ => {
          match read_to_string(&path) {
            Ok(output) => { val.push_str(&output); },
            Err(_) => {
              println!("{}: {}: No such file or directory.", argv0, path);
              process::exit(66); // sysexits(3) EX_NOINPUT
            },
          };
        },
      }
      print!("{}", val);
    }
  }

  io::stdout().flush().unwrap();
}