Webserver(2.8)守护进程

守护进程案例

每隔2s获取系统时间，将这个时间写入到磁盘文件中

#include<stdio.h>
#include<sys/stat.h>
#include<sys/types.h>
#include<unistd.h>
#include<fcntl.h>
#include<sys/time.h>
#include<signal.h>
#include<time.h>
#include<stdlib.h>
#include<string.h>void work(int num){//捕捉到信号之后,获取系统时间，写入磁盘文件time_t tm=time(NULL);struct tm * loc=localtime(&tm);// char buf[1024];// sprintf(buf,"%d-%d-%d %d:%d:%d\n",loc->tm_year,// loc->tm_mon,loc->tm_mday,loc->tm_hour,loc->tm_min,loc->tm_sec);//printf("%s\n",buf);char * str =asctime(loc);int fd=open("time.txt",O_RDWR|O_CREAT|O_APPEND,0664);write(fd,str,strlen(str));close(fd);}int main(){//1.创建子进程，退出父进程pid_t pid=fork();if(pid>0){exit(0);}//2.将子进程提升为会话setsid();//3.设置掩码umask(022);//4.更改工作目录chdir("/home/nowcoder/");//5.关闭、重定向文件描述符int fd=open("/dev/null",O_RDWR);dup2(fd,STDIN_FILENO);dup2(fd,STDOUT_FILENO);dup2(fd,STDERR_FILENO);//6.业务逻辑struct sigaction act;act.sa_flags=0;act.sa_handler=work;sigemptyset(&act.sa_mask);sigaction(SIGALRM,&act,NULL);//捕捉定时信号struct itimerval val;val.it_value.tv_sec=2;val.it_value.tv_usec=0;val.it_interval.tv_sec=2;val.it_interval.tv_usec=0;//创建定时器setitimer(ITIMER_REAL,&val,NULL);//不让进程结束while(1){sleep(10);}return 0;}