This program gives you raw access to the kernel time variables. For a machine connected to the Internet, or equipped with a precision oscillator or radio clock, the best way to keep the system clock correct is with ntpd. However, for a standalone or intermittently connected machine, you may use adjtimex instead to at least correct for systematic drift. adjtimex can optionally adjust the system clock using the CMOS clock as a reference, and can log times for long-term estimation of drift rates.