NAME

       chrony - programs for keeping computer clocks accurate

SYNOPSIS

       chronyc [OPTIONS]

       chronyd [OPTIONS]

DESCRIPTION

       chrony  is  a  pair  of  programs for keeping computer clocks accurate.  chronyd is a background (daemon)
       program and chronyc is a command-line interface to it. Time reference sources for chronyd can be  RFC1305
       NTP  servers,  human  (via  keyboard  and chronyc), or the computer's real-time clock at boot time (Linux
       only). chronyd can determine the rate at which the computer gains or loses time  and  compensate  for  it
       while  no  external  reference  is  present.  Its  use of NTP servers can be switched on and off (through
       chronyc) to support computers with dial-up/intermittent access to the Internet, and it can also act as an
       RFC1305-compatible NTP server.

USAGE

       chronyc is a command-line interface program which can be used to monitor  chronyd's  performance  and  to
       change various operating parameters whilst it is running.

       chronyd's main function is to obtain measurements of the true (UTC) time from one of several sources, and
       correct  the  system  clock  accordingly.   It also works out the rate at which the system clock gains or
       loses time and uses this information to keep it accurate between measurements from the reference.

       The reference time can be derived from either Network Time Protocol (NTP) servers, reference  clocks,  or
       wristwatch-and-keyboard (via chronyc).  The main source of information about the Network Time Protocol is
       http://www.ntp.org.

       It is designed so that it can work on computers which only have intermittent access to reference sources,
       for  example computers which use a dial-up account to access the Internet or laptops.  Of course, it will
       work well on computers with permanent connections too.

       In addition, on Linux it can monitor the system's real time clock performance, so the system can maintain
       accurate time even across reboots.

       Typical accuracies available between 2 machines are

       On an ethernet LAN : 100-200 microseconds, often much better On a V32bis dial-up modem connection :  10's
       of milliseconds (from one session to the next)

       With a good reference clock the accuracy can reach one microsecond.

       chronyd can also operate as an RFC1305-compatible NTP server and peer.

SEE ALSO

       chronyc(1), chrony(1)

       http://chrony.tuxfamily.org/

AUTHOR

       Richard Curnow <rc@rc0.org.uk>

       This  man-page  was  written by Jan Schaumann <jschauma@netmeister.org> as part of "The Missing Man Pages
       Project".  Please see http://www.netmeister.org/misc/m2p2/index.html for details.

       The complete chrony documentation is supplied in texinfo format.

chrony @VERSION@                                   @MAN_DATE@                                          CHRONY(1)