Rust input/output

Documentation

std::fs

https://doc.rust-lang.org/std/fs/index.html

Stdin, Stdout, Stderr

println!("out");   // write to stdout
eprintln!("err");  // write to stderr

read from stdin (wait indefinitely if nothing is written)

use std::io;
use std::io::BufRead;

/// read big files
fn buffered_read_all_stdin() {
    let stdin = io::stdin();
    let handle = stdin.lock();
    let lines: Vec<String> = handle
        .lines()
        .map(|res| res.unwrap_or_default())
        .collect();
    print!("START\n{}\nFINISH\n", lines.join("\n"));
}

manually buffered read from stdin (wait indefinitely if no pipe on stdin)

use std::io::Read;
use std::str;

/// like `tail -f`
fn manually_buffered_read_stdin() {
    let mut buffer: [u8; 8] = [0; 8];
    let stdin = io::stdin();
    let mut handle = stdin.lock();

    loop {
        let bytes_read = handle
            .read(&mut buffer[..])
            .unwrap_or(0);

        // reached EOF
        if bytes_read == 0 {
            break;
        }
        print!("{}", str::from_utf8(&buffer).unwrap());
    }
}

TODO:

read from stdin, checking if it's a tty or a pipe

User Input

let name = String::new();
io::stdin().read_line(&mut name);