C语言编程，加入什么C语言的语句能让程序运行时直接在后台执行呢？

sunguangshou

C语言编程，加入什么C语言的语句能让程序运行时直接在后台执行呢？

linux_c_py_php

NAME
       daemon - run in the background

SYNOPSIS
       #include <unistd.h>

       int daemon(int nochdir, int noclose)

lrita

./a.out &



..............

sunguangshou

回复 3# lrita


我想用代码实现，谢谢

sunguangshou

linux_c_py_php 发表于 2013-01-24 11:13
NAME
       daemon - run in the background

谢谢，我试试先。

cxytz01

1. void daemonize(const char *cmd) {
   
2. 
   
3.     int               i, fd0, fd1, fd2;
   
4.     pid_t             pid;
   
5.     struct rlimit     rl;
   
6.     struct sigaction  sa;
   
7. 
   
8. 
   
9.     /*
   
10.      * Clear file creation mask.
    
11.      */
    
12.     umask(0);
    
13. 
    
14.     /*
    
15.      * Get maximum number of file descriptors.
    
16.      */
    
17.     if (getrlimit(RLIMIT_NOFILE, &rl) < 0)
    
18.         err_quit(LOG_ERR, "%s: can't get file limit", cmd);
    
19. 
    
20.     /*
    
21.      * Become a session leader to lose controlling TTY.
    
22.      */
    
23.     if ((pid = fork()) < 0)
    
24.         err_quit(LOG_ERR, "%s: can't fork", cmd);
    
25.     else if (pid != 0) /* parent */
    
26.       exit(0);
    
27.     setsid();
    
28. 
    
29.     /*
    
30.      * Ensure future opens won't allocate controlling TTYs.
    
31.      */
    
32.     sa.sa_handler = SIG_IGN;
    
33.     sigemptyset(&sa.sa_mask);
    
34.     sa.sa_flags = 0;
    
35.     if (sigaction(SIGHUP, &sa, NULL) < 0)
    
36.         err_quit(LOG_ERR, "%s: can't ignore SIGHUP");
    
37.     if ((pid = fork()) < 0)
    
38.         err_quit(LOG_ERR, "%s: can't fork", cmd);
    
39.     else if (pid != 0)    /* parent */
    
40.         exit(0);
    
41. 
    
42.     /*
    
43.      * Change the current working directory to the root so
    
44.      * we won't prevent file system from being unmounted.
    
45.      *
    
46.      */
    
47.     #if 0
    
48.     if (chdir("/") < 0)
    
49.         err_quit(LOG_ERR, "%s: can't change directory to /");
    
50.     #endif
    
51. 
    
52.     /*
    
53.      * Close all open file descriptors.
    
54.      */
    
55.     if (rl.rlim_max == RLIM_INFINITY)
    
56.         rl.rlim_max = 1024;
    
57.     for (i = 0; i < rl.rlim_max; i++)
    
58.         close(i);
    
59. 
    
60. 
    
61.     /*
    
62.      * Attach file descriptors 0, 1, and 2 to /dev/null.
    
63.      */
    
64.     fd0 = open("/dev/null", O_RDWR);
    
65.     fd1 = dup(0);
    
66.     fd2 = dup(0);
    
67. 
    
68.     #if 0
    
69.     /*
    
70.      * Initialize the log file.
    
71.      */
    
72.     openlog(cmd, LOG_CONS, LOG_DAEMON);
    
73.     if (fd0 != 0 || fd1 != 1 || fd2 != 2) {
    
74.         syslog(LOG_ERR, "unexpected file descriptors %d %d %d",
    
75.             fd0, fd1, fd2);
    
76.         exit(1);
    
77.     }
    
78.     #endif
    
79. }
    

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