Exit with error code in go?

error-handling go exit
dan picture dan · Sep 23, 2013 · Viewed 48.3k times · Source

What's the idiomatic way to exit a program with some error code?

The documentation for Exit says "The program terminates immediately; deferred functions are not run.", and log.Fatal just calls Exit. For things that aren't heinous errors, terminating the program without running deferred functions seems extreme.

Am I supposed to pass around some state that indicate that there's been an error, and then call Exit(1) at some point where I know that I can exit safely, with all deferred functions having been run?

Answer

Gustavo Niemeyer picture Gustavo Niemeyer · Sep 24, 2013

I do something along these lines in most of my real main packages, so that the return err convention is adopted as soon as possible, and has a proper termination:

func main() {
    if err := run(); err != nil {
        fmt.Fprintf(os.Stderr, "error: %v\n", err)
        os.Exit(1)
    }
}

func run() error {
    err := something()
    if err != nil {
        return err
    }
    // etc
}

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