用golang启动一个daemon
1 package main2
3 import (
4 "fmt"
5 "log"
6 "os"
7 "runtime"
8 "syscall"
9 "time"
10 )
11
12 func daemon(nochdir, noclose int) int {
13 var ret, ret2 uintptr
14 var err syscall.Errno
15
16 darwin := runtime.GOOS == "darwin"
17
18 // already a daemon
19 if syscall.Getppid() == 1 {
20 return 0
21 }
22
23 // fork off the parent process
24 ret, ret2, err = syscall.RawSyscall(syscall.SYS_FORK, 0, 0, 0)
25 if err != 0 {
26 return -1
27 }
28
29 // failure
30 if ret2 < 0 {
31 os.Exit(-1)
32 }
33
34 // handle exception for darwin
35 if darwin && ret2 == 1 {
36 ret = 0
37 }
38
39 // if we got a good PID, then we call exit the parent process.
40 if ret > 0 {
41 os.Exit(0)
42 }
43
44 /* Change the file mode mask */
45 _ = syscall.Umask(0)
46
47 // create a new SID for the child process
48 s_ret, s_errno := syscall.Setsid()
49 if s_errno != nil {
50 log.Printf("Error: syscall.Setsid errno: %d", s_errno)
51 }
52 if s_ret < 0 {
53 return -1
54 }
55
56 if nochdir == 0 {
57 os.Chdir("/")
58 }
59
60 if noclose == 0 {
61 f, e := os.OpenFile("/dev/null", os.O_RDWR, 0)
62 if e == nil {
63 fd := f.Fd()
64 syscall.Dup2(int(fd), int(os.Stdin.Fd()))
65 syscall.Dup2(int(fd), int(os.Stdout.Fd()))
66 syscall.Dup2(int(fd), int(os.Stderr.Fd()))
67 }
68 }
69
70 return 0
71 }
72
73 func main() {
74 daemon(0, 1)
75 for {
76 fmt.Println("hello")
77 time.Sleep(1 * time.Second)
78 }
79
80 }
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