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Copy pathcode.cpp
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93 lines (90 loc) · 1.78 KB
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#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <time.h>
#include <stdio.h>
static bool flag = true;
void create_daemon();
void handler(int);
int main()
{
time_t t;
int fd;
create_daemon();
struct sigaction act;
act.sa_handler = handler;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
if(sigaction(SIGQUIT, &act, NULL))
{
printf("sigaction error.\n");
exit(0);
}
while(flag)
{
fd = open("/home/mick/daemon.log", O_WRONLY | O_CREAT | O_APPEND, 0644);
if(fd == -1)
{
printf("open error\n");
}
t = time(0);
char *buf = asctime(localtime(&t));
write(fd, buf, strlen(buf));
close(fd);
sleep(60);
}
return 0;
}
void handler(int sig)
{
printf("I got a signal %d\nI'm quitting.\n", sig);
flag = false;
}
void create_daemon()
{
pid_t pid;
/*(1)-----创建一个进程来用作守护进程-----*/
pid = fork();
if(pid == -1)
{
printf("fork error\n");
exit(1);
}
/*(1.1)-----------原父进程退出-------------*/
else if(pid)
{
exit(0);
}
/*(2)---setsid使子进程独立。摆脱会话控制、摆脱原进程组控制、摆脱终端控制----*/
if(-1 == setsid())
{
printf("setsid error\n");
exit(1);
}
/*(3)---通过再次创建子进程结束当前进程，使进程不再是会话首进程来禁止进程重新打开控制终端----*/
pid = fork();
if(pid == -1)
{
printf("fork error\n");
exit(1);
}
else if(pid)
{
exit(0);
}
/*(4)---子进程中调用chdir()让根目录成为子进程工作目录----*/
chdir("/");
int i;
/*(6)---关闭文件描述符(常说的输入，输出，报错3个文件)----*/
for(i = 0; i < 3; ++i)
{
close(i);
}
/*(5)---重设文件掩码为0（将权限全部开放）----*/
umask(0);
return;
}