NAME

       chronyd - chrony background daemon

SYNOPSIS

       chronyd [OPTIONS]

DESCRIPTION

       chrony is a pair of programs for maintaining the accuracy of computer clocks. chronyd is a
       background daemon program that can be started at boot time.

       chronyd is a daemon which runs in background on the system.  It obtains measurements (e.g.
       via  the network) of the system's offset relative to other systems, and adjusts the system
       time accordingly.  For isolated systems, the user can periodically enter the correct  time
       by  hand  (using  chronyc).   In  either  case,  chronyd  determines the rate at which the
       computer gains or loses time, and compensates for this.

USAGE

       chronyd is usually started at boot-time and requires superuser privileges.

       If chronyd has been installed to its default location /usr/sbin/chronyd,  starting  it  is
       simply a matter of entering the command:

       /usr/sbin/chronyd

       Information messages and warnings will be logged to syslog.

OPTIONS

       A summary of the options supported by chronyd is included below.

       -P priority
              This  option  will  select  the  SCHED_FIFO  real-time  scheduler  at the specified
              priority (which must be between 0 and 100).  This mode is supported only on Linux.

       -m     This option will lock chronyd into RAM so that it will never be  paged  out.   This
              mode is only supported on Linux.

       -n     When run in this mode, the program will not detach itself from the terminal.

       -d     When  run  in  this mode, the program will not detach itself from the terminal, and
              all messages will be sent to the terminal instead of to syslog.

       -f conf-file
              This option can be used to specify an alternate location for the configuration file
              (default /etc/chrony/chrony.conf).

       -r     This option will reload sample histories for each of the servers being used.  These
              histories are created by using the dump command  in  chronyc,  or  by  setting  the
              dumponexit  directive in the configuration file.  This option is useful if you want
              to stop and restart chronyd briefly for any reason, e.g. to install a new  version.
              However,  it  only  makes  sense  on  systems  where  the kernel can maintain clock
              compensation whilst not under chronyd's  control.   The  only  version  where  this
              happens  so  far is Linux.  On systems where this is not the case, e.g. Solaris and
              SunOS the option should not be used.

       -R     When this option is used, the initstepslew directive  and  the  makestep  directive
              used  with  a positive limit will be ignored. This option is useful when restarting
              chronyd and can be used in conjunction with the -r option.

       -s     This option will set the system clock from the computer's real-time clock.  This is
              analogous to supplying the -s flag to the /sbin/clock program during the Linux boot
              sequence.

              Support for real-time clocks is limited at present - the criteria are described  in
              the  section  on  the  rtcfile  directive  in  the  documentation supplied with the
              distribution.

              If chronyd cannot support the real time clock on your computer, this option  cannot
              be used and a warning message will be logged to the syslog.

              If  used  in conjunction with the -r flag, chronyd will attempt to preserve the old
              samples after setting the system clock from the real time clock.  This can be  used
              to  allow  chronyd  to  perform long term averaging of the gain or loss rate across
              system reboots, and is useful for dial-up systems that are shut down  when  not  in
              use.   For  this  to  work well, it relies on chronyd having been able to determine
              accurate statistics for the difference between the real time clock and system clock
              last time the computer was on.

       -u user
              When  this option is used, chronyd will drop root privileges to the specified user.
              So far, it works only on Linux when compiled with capabilities support.

       -v     This option displays chronyd's version number to the terminal and exits

       -4     Resolve hostnames only to IPv4 addresses and create only IPv4 sockets.

       -6     Resolve hostnames only to IPv6 addresses and create only IPv6 sockets.

FILES

       /etc/chrony/chrony.conf

BUGS

       To report bugs, please visit http://chrony.tuxfamily.org/

SEE ALSO

       chronyd is documented in detail  in  the  documentation  supplied  with  the  distribution
       (chrony.txt and chrony.texi) and is also available from http://go.to/chrony

       chrony(1), chronyc(1), chrony.conf(5), hwclock(8), ntpd(8)

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.