SDB:Your Computer Clock Shows the Wrong Time

Symptom

Your computer clock shows the wrong time.

Cause

Your computer's time has been probably set with hwclock without paying much attention to its features.

Solution

The RTC clock, i.e. the clock that keeps on working when the computer is switched off, does not usually work very exactly. The program hwclock enables to correct this inaccuracy, in spite of lacking an NTP, by compensating a constant inaccuracy. The necessary data are saved in /etc/adjtime. To prevent the RTC clock from becoming even more inaccurate, it must be timed exactly to the second with hwclock or the timing process must be performed twice in a short interval.

Delete the file /etc/adjtime and set the time precisely with hwclock by means of an exact clock (e.g. a radio controlled clock). For example:

hwclock --set --date="7/22/01 17:45:05"

If the RTC clock's time is the GMT, the option -u has to be specified so that the time difference can be observed. In order to maintain the time as precise as possible, this procedure shall be repeated several times the week after at the soonest. The run-time difference will be calculated and, from then on, it will be automatically corrected. If these rules are observed, the clock will show the right time in the future.

SDB:Setting the clock to GMT (Greenwich Mean Time)

SDB:Time Synchronization Through the Network

There is also a helpful article in the Unofficial SuSEFAQ [1]

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