clock

Hurricane Electric Internet Services: Accounts starting at $9.95/month
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: Accounts starting at $9.95/month
Hurricane Electric Internet Services
Copyright (C) 1998 Hurricane Electric. All Rights Reserved.