Linux系统调用——文件操作读取获取运行时间写入日志文件

功能描述：程序运行时实时显示（1秒钟刷新一次），程序运行开始和结束时显示上一次运行结束时间；程序结束时将结束时间写入日志文件中【即程序记录开始时间和结束时间】；
file.c

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

#define TIME_STR_MAX_LEN 20
#define TIME_LOOP_SECONDS 10 * 1
#define TIME_DATA_FILE "time_data.txt"
typedef struct _time_struct {
    
    
    int year;
    int month;
    int day;
    int hour;
    int min;
    int second;
    int isdst;
}TimeStruct;

TimeStruct GetCurrentTime();

int main()
{
    
    
    int timeFd = open(TIME_DATA_FILE, O_RDWR | O_CREAT);
    char curTimeStr[TIME_STR_MAX_LEN] = {
    
    0};
    TimeStruct curTime;

    int ret = lseek(timeFd,0, SEEK_END);
    if(ret == -1) {
    
    
        perror("lseek error.");
        return -1;
    } else if(ret == 0) {
    
    
        curTime = GetCurrentTime();      
        sprintf(curTimeStr, "%d-%d-%d %d:%d:%d\n", curTime.year, curTime.month, curTime.day,
                curTime.hour, curTime.min, curTime.second);
        printf("process run first time at:%s.\n", curTimeStr);
    } else {
    
    
        ret = lseek(timeFd,-(sizeof(curTimeStr)), SEEK_END);
        read(timeFd, curTimeStr, sizeof(curTimeStr));
        printf("last time process end at:%s.\n", curTimeStr);
    }
    ret = write(timeFd, curTimeStr, sizeof(curTimeStr));
    if(ret == -1) {
    
    
        perror("write error.");
        return -1;
    }
    int loopSeonds = 0;
    while(loopSeonds < TIME_LOOP_SECONDS){
    
    
        curTime = GetCurrentTime();  
        sprintf(curTimeStr, "%d-%d-%d %d:%d:%d\n", curTime.year, curTime.month, curTime.day,
            curTime.hour, curTime.min, curTime.second);
        printf("%s", curTimeStr);
        sleep(1);
        loopSeonds++;
    }
    ret = write(timeFd, curTimeStr, sizeof(curTimeStr));
    if(ret == -1) {
    
    
        perror("write error.");
        return -1;
    }
    close(timeFd);
    printf("file operation completed.\n");
    return 0;
}

TimeStruct GetCurrentTime()
{
    
    
    time_t tempTime;
    struct tm *curTime;
    time(&tempTime);
    curTime = gmtime(&tempTime);

    TimeStruct destTime;
    destTime.year = curTime->tm_year + 1900;
    destTime.month = curTime->tm_mon + 1;
    destTime.day = curTime->tm_mday;
    destTime.hour = curTime->tm_hour + 8;
    destTime.min = curTime->tm_min;
    destTime.second = curTime->tm_sec;
    destTime.isdst = curTime->tm_isdst;
    return destTime;
}