#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <errno.h>

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <time.h>

void sysErr(const char* err,int status)
{
    perror(err);
    exit(status);
}

void deamonize()
{
    pid_t pid;
    pid = fork();
    if (pid > 0)
    {
        exit(0);
    }
    else if (pid < 0)
    {
        sysErr("fork",-1);
    }

    setsid();// 子进程创建会话，独立出来，脱离控制

    // 改变工作路径、
//    if (chdir("/") != 0)
//    {
//        sysErr("chdir",errno);
//    }

    // 重设文件掩码
    umask(0);

    close(0);
    open("/dev/null",O_RDWR);
    dup2(1,0);
    dup2(2,0);
}

void writeLog(const char* buf)
{
    int fdLog;
    fdLog = open("./deamon.log",O_RDWR | O_APPEND | O_CREAT,0644);
    if (fdLog < 0)
    {
        sysErr("open log file failed.",errno);
    }
    // 时间
    char bufTime[64] = {0};
    time_t now_t;
    time(&now_t);
    struct tm ptimeT = {0};
           localtime_r(&now_t,&ptimeT); 
    sprintf(bufTime,"%04d-%02d-%02d-%02d-%02d-%02d:",ptimeT.tm_year+1900,ptimeT.tm_mon+1,ptimeT.tm_mday,
            ptimeT.tm_hour,ptimeT.tm_min,ptimeT.tm_sec);
    write(fdLog,bufTime,strlen(bufTime));
    write(fdLog,buf,strlen(buf));
    close(fdLog);
}

int main(int argc, char **argv)
{
    deamonize();
    // 守护进程核心工作
    while(1)
    {
        writeLog("hello\n");
        sleep(2);
    }
    return 0;
}