02_Tow_clocks_in_linux

1. The system clock
    Timing by the Linux kernel by the working frequency of the CPU.
    The date command query and set the system clock.
2. The hardware clock
    The clock/hwclock command query and set the hareware clock.
3.    How to synchronize the system clock with the hardware clock.
    hwclock -s : Set the system time from the hardware Clock.
            -w : Set the Hardware clock to the current system time.