守护进程（源代码）

#include  "unp.h"

#include 

 

#define MAXFD   64

 

extern int daemon_proc; /* defined in error.c */

 

int

daemon_init(const char *pname, int facility)

{

   int     i;

   pid_t   pid;

 

   if ( (pid = Fork()) < 0)

     return (-1);

   else if (pid)

     _exit(0);      /* parent terminates */

 

   /* child 1 continues... */

 

   if (setsid() < 0)      /* become session leader */

     return (-1);

 

   Signal(SIGHUP, SIG_IGN);

   if ( (pid = Fork()) < 0)

     return (-1);

   else if (pid)

     _exit(0);      /* child 1 terminates */

 

   /* child 2 continues... */

 

   daemon_proc = 1;       /* for err_XXX() functions */

 

   chdir("/");         /* change working directory */

   umask(0);

 

   /* close off file descriptors */

   for (i = 0; i < MAXFD; i )

     close(i);

 

   /* redirect stdin, stdout, and stderr to /dev/null */

   open("/dev/null", O_RDONLY);

   open("/dev/null", O_RDWR);

   open("/dev/null", O_RDWR);

 

   openlog(pname, LOG_PID, facility);

 

   return (0);         /* success */

}