我编写了一个示例代码来使用clock_settime设置时间。

#include <time.h>
#include <sys/time.h>
#include <stdio.h>
#include <unistd.h>

int main(int argc,char argv[])
{
    struct timespec walltime;

    clock_gettime(CLOCK_REALTIME,&walltime);
    perror("clock_gettime");
    printf("Current wall time:%s\n",ctime(&walltime.tv_sec));

    walltime.tv_sec += 10*60;
    printf("Setting wall time to :%s\n",ctime(&walltime.tv_sec));
    clock_settime(CLOCK_REALTIME,&walltime);
    perror("clock_settime");

    clock_gettime(CLOCK_REALTIME,ctime(&walltime.tv_sec));
    return 0;
}

程序输出：

clock_gettime: Success
Current wall time:Mon Nov  4 03:24:43 2019

Setting wall time to :Mon Nov  4 03:34:43 2019

clock_settime: Success
clock_gettime: Success
Current wall time:Mon Nov  4 03:34:43 2019

看起来正确，但是当我第二次运行它时，新时间不会更新。

clock_gettime: Success
Current wall time:Mon Nov  4 03:25:12 2019

Setting wall time to :Mon Nov  4 03:35:12 2019

clock_settime: Success
clock_gettime: Success
Current wall time:Mon Nov  4 03:35:12 2019

Date命令还会显示旧值。

$ date
Mon Nov  4 03:25:30 PST 2019

此行为正确吗