clock
Hurricane Electric Internet Services
NAME
clock - manipulate the CMOS clock
SYNOPSIS
/sbin/clock [ -u ] -r
/sbin/clock [ -u ] -w
/sbin/clock [ -u ] -s
/sbin/clock [ -u ] -a
DESCRIPTION
clock manipulates the CMOS clock in variaous ways, allow-
ing it to be read or written, and allowing synchronization
between the CMOS clock and the kernel's version of the
system time.
OPTIONS
-u Indicates that the CMOS clock is set to Universal
Time.
-r Read CMOS clock and print the result to stdout.
-w Write the system time into the CMOS clock.
-s Set the system time from the CMOS clock.
-a Set the system time from the CMOS clock, adjusting
the time to correct for systematic error, and writ-
ting it back into the CMOS clock.
This option uses the file /etc/adjtime to determine
how the clock changes. It contains three numbers:
The first number is the correction in seconds per
day (for example, if your clock runs 5 seconds fast
each day, the first number should read -5.0).
The second number tells when clock was last used,
in seconds since 1/1/1970.
The third number is the remaining part of a second
that was left over after the last adjustment.
The following instructions are from the source
code:
a) create a file /etc/adjtime containing as the
first and only line: '0.0 0 0.0'
b) run clock -au or clock -a, depending on
whether your CMOS is in Universal or Local
Time. This updates the second number.
c) set your system time using the date command.
d) update your CMOS time using clock -wu or
clock -w
e) replace the first number in /etc/adjtime by
your correction.
f) put the command clock -au or clock -a in
your /etc/rc.local, or let cron(8) start it
regularly.
FILES
/etc/adjtime
/etc/rc.local
AUTHORS
V1.0 Charles Hedrick, hedrick@cs.rutgers.edu, Apr 1992
V1.1 Modified for clock adjustments, Rob Hooft,
hooft@chem.ruu.nl, Nov 1992
V1.2 Patches by Harald Koenig,
koenig@nova.tat.physik.uni-tuebingen.de, applied by
Rob Hooft, hooft@EMBL-Heidelberg.DE, Oct 1993
Hurricane Electric Internet Services
Copyright (C) 1998
Hurricane Electric.
All Rights Reserved.