Provided by: chrony_2.1.1-1_i386 bug


       chronyd - chrony background daemon


       chronyd [OPTIONS] [configuration commands]


       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.


       chronyd  is  usually  started  at  boot-time  and  requires   superuser

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


       Information messages and warnings will be logged to syslog.

       If no configuration commands are specified on the command line, chronyd
       will  read  the  commands  from   the   configuration   file   (default


       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.  When chronyd was compiled with debugging
              support, this option can be used twice to print  also  debugging

       -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 other systems this 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/hwclock 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 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  (RTC).   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 RTC and system clock  last  time  the
              computer was on.

              If  chronyd doesn't support the RTC on your computer or there is
              no RTC installed, the system clock will be set with this  option
              forward  to  the time of the last modification of the drift file
              (specified by the driftfile directive)  to  restore  the  system
              time at which chronyd was previously stopped.

       -u user
              This  option  sets  the  name  of the user to which will chronyd
              switch  to  drop  root  privileges  if   compiled   with   Linux
              capabilities support (default _chrony).

       -q     When  run  in  this mode, chronyd will set the system clock once
              and exit.  It will not detach from the terminal.

       -Q     This option is similar to -q, but it will only print the  offset
              and not correct the clock.

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

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

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




       To report bugs, please visit


       chronyd is documented in detail in the documentation supplied with  the
       distribution (chrony.txt and chrony.texi).

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


       Richard Curnow <>

       This man-page was written by Jan Schaumann <> as
       part   of   "The   Missing   Man   Pages    Project".     Please    see for details.

       The complete chrony documentation is supplied in texinfo format.