#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <syslog.h>
#include <signal.h>
static int daemon_init(char *name, int dochdir, int doclosefd)
{
pid_t pid, sid, deadChildPid;
time_t timebuf;
int fd = -1;
if(name == NULL)
{
return -1;
}
pid = fork();
if (pid < 0)
{
perror( "fork ");
return -1;
}
//father process exit
if(pid > 0)
{
exit(0);
}
//child continues
//become session leader
if((sid = setsid()) < 0)
{
perror( "setsid ");
exit(1);
}
//change working directory
if(dochdir)
{
if((chdir("/")) < 0)
{
perror( "chdir ");
exit(2);
}
}
//clear our file mode creation mask
umask(0);
//将标准输入输出重定向到空设备
if(doclosefd)
{
fd = open ("/dev/null", O_RDWR, 0);
if (fd != -1)
{
dup2 (fd, STDIN_FILENO);
dup2 (fd, STDOUT_FILENO);
dup2 (fd, STDERR_FILENO);
if (fd > 2)
close (fd);
}
}
if((pid=fork()) == 0)
{
return 0;
}
else if(pid > 0)
{
deadChildPid = wait(NULL);
printf("create a new process !\n");
if(execl(name, name, "executed by execl", NULL)<0)
perror("Err on execl");
}
exit(0);
}
int main(int argc, char *argv[])
{
daemon_init("./test", 0, 0);
while(1)
{
printf("The process ID is %d\n", (int)getpid());
printf("The parent process ID is %d\n", (int)getppid());
sleep(5);
}
return 0;
}