linux-l: hwclock && timeserver

[Robin S. Socha]

* Bernd Freistedt <bf at bcf.in-berlin.de> writes:
> zum Beispiel:
>     `netdate -v time.fu-berlin.de > /dev/null ; /sbin/clock -uw`

Ein anderes Beispiel:

/usr/sbin/netdate wuarchive.wustl.edu ntp3.cs.wisc.edu ns3.univie.ac.at \ 
ntps1-1.uni-osnabrueck.de time.fu-berlin.de ntp.Uni-Augsburg.DE \
ntp.server.uni-frankfurt.de chime1.surfnet.nl ntps1-0.cs.tu-berlin.de \
ws-mue1.win- ip.dfn.de && hwclock --systohc --utc --debug

Warum?

man netdate:
       The  ''best''  time  is  chosen by polling the named hosts
       once each to find their times and taking their differences
       from the local host's time.  These differences are used to
       find the largest group of hosts  whose  times  agree  with
       each  other within a certain limit.  The first host in the
       largest group is picked as the best host.  (The assumption
       is  that the hosts which are usually most accurate will be
       named first.)  That host is polled  again  and  the  local
       host's  time is set to the result.  The chosen host's time
       is checked on this second poll to insure that its  differ-
       ence  from  the local host's time has not varied more than
       the limit from its difference at the first poll.

man hwclock

       --systohc
              Set the Hardware Clock to the current System  Time.
       --utc  Indicates that the Hardware Clock is kept in  Coor-
              dinated  Universal Time.  It is your choice whether
              to keep your clock in UTC or local time, but  noth-
              ing  in  the  clock  tells which you've chosen.  So
              this option is how you  give  that  information  to
              hwclock.
       --debug
              Display  a lot of information about what hwclock is
              doing internally.  Some of its function is  complex
              and  this  output  can  help you understand how the
              program works.
-- 
Robin S. Socha  <http://socha.net/>