How to do it...

1. Open the Cargo.toml file that was generated earlier for you.

2. Under [dependencies], if you didn't do so in the last recipe, add the following line:

log = "0.4.1"

If you want, you can go to log's crates.io page (https://crates.io/crates/log) to check for the newest version and use that one instead.

3. In the folder bin, create a file called custom_logger.rs.
4. Add the following code and run it with RUST_LOG=custom_logger cargo run --bin custom_logger if you're on a Unix-based system. Otherwise, run $env:RUST_LOG="custom_logger"; cargo run --bin custom_logger on Windows:

1   #[macro_use]
2   extern crate log;
3 
4   use log::{Level, Metadata, Record};
5   use std::fs::{File, OpenOptions};
6   use std::io::{self, BufWriter, Write};
7   use std::{error, fmt, result};
8   use std::sync::RwLock;
9   use std::time::{SystemTime, UNIX_EPOCH};
10 
11  // This logger will write logs into a file on disk
12  struct FileLogger {
13    level: Level,
14    writer...