Projects / hwclock


Hwclock is a program that runs under Linux and sets and queries the Hardware Clock, which is often called the Real Time Clock, RTC, or CMOS clock. This is the program that most Linux systems use to get the time from the Hardware Clock and set the System Time at boot time. This program works on ISA (Intel), Alpha, SPARC, and M68K systems with or without /dev/rtc.

Operating Systems

Recent releases

  •  01 Aug 2007 18:07

    Release Notes: This release is much more accurate (down to the microsecond) and works on more systems (hardware and software) than 2.11.

    •  18 Feb 2001 05:45

      Release Notes: This release avoids the hang (usually a boot time hang) on machines with broken rtc drivers by timing out after 2 seconds waiting for the clock interrupt, then falling back to a non-interrupt clock access method. Changes since Release 2.9 include fixes of compile errors on Sparc, improvements to the accuracy of the --adjust function, and correct handling of daylight savings time with GNU libc 2.

      •  30 May 2000 17:51

        Release Notes: A .5 second setting error on most systems is fixed. The hardware clock can now be set with several millisecond accuracy. Hwclock --hctosys now logs time-change records to utmp/wtmp. The timezone is included in the time display to remove a common source of confusion. There are several minor improvements to the documentation.

        •  04 May 1999 02:16

          Release Notes: In --hctosys, account for uncorrected (accumulated) drift, move tzset() so the possible slow reading of files it does does not impact timing, correct check for improbably large drift so it checks the absolute value of the drift and some debug output in days instead of seconds.


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