Ubuntu Feisty 7.04 manual page repository

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Provided by: zaptel_1.2.15~dfsg-1_i386

NAME

        adj_clock — Synchronize system clock to zaptel clock
 

SYNOPSIS

        adj_clock [ -c count ] [ -i interval ] [ -t period ] [ -v ]
 

DESCRIPTION

        adj_clock  compares  synchronizes the system clock from Zaptel’s clock:
        in each cycle It will read 1024 * interval ticks from a  Zaptel  pseudo
        channel,  which  should  take exactly interval seconds. It measures the
adjtimex(3) to fix the system clock  accord‐
        ingly.
 
        Note  that  NTP  servers  usually  use  adjtimex.  You  may get strange
ntpd(8))  running  on  the
        system.
 
        Output  is  sent  to  both the standard error and to the syslog. Syslog
        messages are with facility daemon.
 

OPTIONS

        -c count
               Run just count synchronization cycles. Default is  to  run  for‐
               ever.
 
        -i interval
               Loop  interval (in seconds). Optional, as program should provide
               a sane value.
 
               Small values allow faster synchronization  when  the  system  is
               quiet.  Even  a value as low as 10 should work. However they are
               much more suspectable to short interruptions.
 
        -t period
               Set the synchronization  tolerance  priod  (micro-seconds).  The
               default  is  100.  Don’t  touch  it  unless you know what you’re
               doing.
 
        -v
               Be more verbose: log status messages even when synchronized.
 

FILES

        /dev/zap/pseudo
        The device file used to open a "pseudo" channel (a channels  that  con‐
        stantly streams voice and is synchronized by the master Zaptel device).
 

SYNCHRONIZATION

        Some more technical details. This explains the strange numbers the pro‐
        gram prints.
 
        In  each  cycle adj_clock measures interval seconds using Zaptel ticks.
gettimeofday(2). It  then
adjtimex(2)  to slightly change the rate of the system clock. It
        uses two parameters: ticks, which is a more coarse  one  (1  tick  will
        give  roughly  a  change  of  rate of 9 seconds per day) and frequency,
        which allows much finer settings.
 
        The program tries to set what it can by ticks,  and  the  rest  through
        frequency.  It considers itself "synchronized" when the rate difference
        is small enough so (a) It does not have to use ticks anymore.  And  (b)
        The rest of the interval to change is smaller than the tolerance period
        (100 micro-seconds, by default).
 
        The meaning of the parameters it prints is, thus:
 
        interval
               The current interval parameter (seconds).
 
        diff_tick
adjtimex(2).   Any‐
               thing different than 0 means we’re still way off mark.
 
        diff_usec
               The  time difference (micro-seconds) that we need to overcome in
               the first place. This is the difference between the system clock
               and the measured zaptel clock.
 
        usec_left
               How  much  of  this  difference  (microseconds) we still need to
               adjust after using ticks. This should be low enough  (less  than
               the tolerance period).
 

SIGNALS

        adj_clock  is so far an interactive program, and thus killed by SIGHUP.
        SIGUSR is used to increase verbosity level and SIGUSR2 is used to reset
        verbosity  level  to  0. When SIGUSR1 is recieved a status message will
        also be sent to the logs.
adjtimex(8)
 

AUTHOR

        This manual page  was  written  by  Tzafrir  Cohen  <tzafrir.cohen@xor‐
        com.com>  Permission  is granted to copy, distribute and/or modify this
        document under the terms of the GNU General Public License,  Version  2
        any later version published by the Free Software Foundation.
 
        On  Debian systems, the complete text of the GNU General Public License
        can be found in /usr/share/common-licenses/GPL.
 
adj_clock(8)