Useful go snippets

daemon.go

package main

import (
	"os"
	"syscall"
	"os/exec"
	"fmt"
)

// Start daemon function
// Works under linux, not tested with other platforms
func StartDaemon(name string, arg ...string) (int, error) {
    ret, ret2, syserr := syscall.RawSyscall(syscall.SYS_FORK, 0, 0, 0)
    if syserr != 0 || ret < 0 || ret2 < 0 {
        return -1, fmt.Errorf("Error forking child process")
    }

    // parent process
    if ret > 0 {
        return int(ret), nil
    } else {
        // clear umask
        _ = syscall.Umask(0)
        syscall.Setsid()

        err := exec.Command(name, arg...).Run()
	if err != nil {
		os.Exit(1)
	} else {
		os.Exit(0)
	}
    }
    return 0, nil
}

func main() {
	pid, err := StartDaemon("sleep", "30")
	if err != nil {
		fmt.Fprintln(os.Stderr, "Spawned subprocess: ", pid)
		os.Exit(1)
	} else {
		fmt.Println("Spawned subprocess: ", pid)
	}
}