golang 守護進程(daemon)

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package main import (    "fmt"    "log"    "os"    "runtime"    "syscall"    "time") func daemon(nochdir, noclose int) int {    var ret, ret2 uintptr    var err syscall.Errno     darwin := runtime.GOOS == "darwin"     // already a daemon    if syscall.Getppid() == 1 {        return 0    }     // fork off the parent process    ret, ret2, err = syscall.RawSyscall(syscall.SYS_FORK, 0, 0, 0)    if err != 0 {        return -1    }     // failure    if ret2 < 0 {        os.Exit(-1)    }     // handle exception for darwin    if darwin && ret2 == 1 {        ret = 0    }     // if we got a good PID, then we call exit the parent process.    if ret > 0 {        os.Exit(0)    }     /* Change the file mode mask */    _ = syscall.Umask(0)     // create a new SID for the child process    s_ret, s_errno := syscall.Setsid()    if s_errno != nil {        log.Printf("Error: syscall.Setsid errno: %d", s_errno)    }    if s_ret < 0 {        return -1    }     if nochdir == 0 {        os.Chdir("/")    }     if noclose == 0 {        f, e := os.OpenFile("/dev/null", os.O_RDWR, 0)        if e == nil {            fd := f.Fd()            syscall.Dup2(int(fd), int(os.Stdin.Fd()))            syscall.Dup2(int(fd), int(os.Stdout.Fd()))            syscall.Dup2(int(fd), int(os.Stderr.Fd()))        }    }     return 0} func main() {    daemon(0, 1)    for {        fmt.Println("hello")        time.Sleep(1 * time.Second)    } }