A common pattern is something like: fn main() { if let Err(e) = real_main() { let status = status_from_error(e); // print the error

A common pattern is something like: fn main() { if let Err(e) = real_main() { let status = status_from_error(e); // print the error message, or whatever std::process:exit(status); } } fn real_main() -> Result<(), TopErrorType> { // ... } And simply returning Result<_, SomethingConvertibleToTopErrorType> from functions called by real_main that might need to exit the program. I believe that in a recent stable version of Rust, you can make this even simpler and have `main()` return a Result directly. edit: not quite as simple as I described, but maybe more powerful because of the Termination trait: https://github.com/rust-lang/rfcs/blob/master/text/1937-ques-in-main.md https://github.com/rust-lang/rfcs/blob/master/text/1937-ques... see: https://github.com/rust-lang/rfcs/blob/master/text/1937-ques-in-main.md#how-we-teach-this https://github.com/rust-lang/rfcs/blob/master/text/1937-ques... fn main() -> Result<(), io::Error> { let mut stdin = io::stdin(); let mut raw_stdout = io::stdout(); let mut stdout = raw_stdout.lock(); for line in stdin.lock().lines() { stdout.write(line?.trim().as_bytes())?; stdout.write(b"\n")?; } stdout.flush() }