Simple use of env_logger

[package]
name = "env-logger-demo"
version = "0.1.0"
edition = "2024"

[dependencies]
env_logger = "0.11.8"
log = "0.4.27"

fn main() {
    env_logger::init();

    log::trace!("This is a sample trace.");
    log::debug!("This is a sample debug.");
    log::info!("This is a sample info.");
    log::warn!("This is a sample warn.");
    log::error!("This is a sample error.");
}

By default this sets the log-level to ERROR so if we run the code we get a single log:

$ cargo run

[2025-04-26T04:59:00Z ERROR env_logger_demo] This is a sample error.

The user can control the level of the logging by setting the RUST_LOG environment variable.

On Linux and macOS you can do it this way:

$ RUST_LOG=trace cargo run

[2025-04-26T04:59:57Z TRACE env_logger_demo] This is a sample trace.
[2025-04-26T04:59:57Z DEBUG env_logger_demo] This is a sample debug.
[2025-04-26T04:59:57Z INFO  env_logger_demo] This is a sample info.
[2025-04-26T04:59:57Z WARN  env_logger_demo] This is a sample warn.
[2025-04-26T04:59:57Z ERROR env_logger_demo] This is a sample error.

In Windows in CMD

> set RUST_LOG=trace

In PowerShell

> [Environment]::SetEnvironmentVariable("RUST_LOG", "trace", "Process")