Logging Rust programs

Question

If we have following code

fn main() {
    error!("This is an error log")
    warn!("This is a warn log")
    info!("this is an info log")
    debug!("This is a debug log")
}

How do we enable the debug level output on Windows?

Answer 1

When executing your program, you need to set the RUST_LOG environment variable appropriately; it is (as far as this is concerned) a comma-separated key=value list; the keys are crate or module names, e.g. extra or std::option; the values are numbers, mapped to log levels:

• 1: error
• 2: warn
• 3: info
• 4: debug

(Each level includes the more significant levels.)

In Command Prompt, compiling and running myprog with showing warnings and errors would be something like:

rustc myprog.rs
set RUST_LOG=myprog=4
myprog.exe

Answer 2

You can set the logging level in the program by setting them to your environment as well. The statement you have to write is:

RUST_LOG=YOUR-PROJECT-NAME=log_level

eg: RUST_LOG=Hello-World=info or RUST_LOG=Hello-World=3

After setting your log level the next step is to initialize them by using env_logger::init().