ntpd(1) Programmer's Manual ntpd(1)
NAME
ntpd - NTP daemon program
SYNOPSIS
ntpd [-flag [value]]... [--opt-name [[=| ]value]]...
All arguments must be options.
DESCRIPTION
This manual page briefly documents the ntpd command.
OPTIONS
-4, --ipv4
Force IPv4 DNS name resolution. This option must not appear in
combination with any of the following options: ipv6.
Force DNS resolution of following host names on the command line
to the IPv4 namespace.
-6, --ipv6
Force IPv6 DNS name resolution. This option must not appear in
combination with any of the following options: ipv4.
Force DNS resolution of following host names on the command line
to the IPv6 namespace.
-a, --authreq
Require crypto authentication. This option must not appear in
combination with any of the following options: authnoreq.
Require cryptographic authentication for broadcast client, mul-
ticast client and symmetric passive associations. This is the
default.
-A, --authnoreq
Do not require crypto authentication. This option must not
appear in combination with any of the following options:
authreq.
Do not require cryptographic authentication for broadcast
client, multicast client and symmetric passive associations.
This is almost never a good idea.
-b, --bcastsync
Allow us to sync to broadcast servers.
-c string, --configfile=string
configuration file name.
The name and path of the configuration file, /etc/ntp.conf by
default.
-d, --debug-level
Increase output debug message level. This option may appear an
unlimited number of times.
Increase the debugging message output level.
-D string, --set-debug-level=string
Set the output debug message level. This option may appear an
unlimited number of times.
Set the output debugging level. Can be supplied multiple times,
but each overrides the previous value(s).
-f string, --driftfile=string
frequency drift file name.
The name and path of the frequency file, /etc/ntp.drift by
default. This is the same operation as the driftfile driftfile
configuration specification in the /etc/ntp.conf file.
-g, --panicgate
Allow the first adjustment to be Big. This option may appear an
unlimited number of times.
Normally, ntpd exits with a message to the system log if the
offset exceeds the panic threshold, which is 1000 s by default.
This option allows the time to be set to any value without
restriction; however, this can happen only once. If the thresh-
old is exceeded after that, ntpd will exit with a message to the
system log. This option can be used with the -q and -x options.
See the tinker configuration file directive for other options.
-i string, --jaildir=string
Jail directory.
Chroot the server to the directory jaildir This option also
implies that the server attempts to drop root privileges at
startup. You may need to also specify a -u option. This option
is only available if the OS supports adjusting the clock without
full root privileges. This option is supported under NetBSD
(configure with --enable-clockctl ) and Linux (configure with
--enable-linuxcaps ).
-I iface, --interface=iface
Listen on an interface name or address. This option may appear
an unlimited number of times.
Open the network address given, or all the addresses associated
with the given interface name. This option may appear multiple
times. This option also implies not opening other addresses,
except wildcard and localhost. This option is deprecated.
Please consider using the configuration file interface command,
which is more versatile.
-k string, --keyfile=string
path to symmetric keys.
Specify the name and path of the symmetric key file.
/etc/ntp.keys is the default. This is the same operation as the
keys keyfile configuration file directive.
-l string, --logfile=string
path to the log file.
Specify the name and path of the log file. The default is the
system log file. This is the same operation as the logfile log-
file configuration file directive.
-L, --novirtualips
Do not listen to virtual interfaces.
Do not listen to virtual interfaces, defined as those with names
containing a colon. This option is deprecated. Please consider
using the configuration file interface command, which is more
versatile.
-M, --modifymmtimer
Modify Multimedia Timer (Windows only).
Set the Windows Multimedia Timer to highest resolution. This
ensures the resolution does not change while ntpd is running,
avoiding timekeeping glitches associated with changes.
-n, --nofork
Do not fork.
-N, --nice
Run at high priority.
To the extent permitted by the operating system, run ntpd at the
highest priority.
-p string, --pidfile=string
path to the PID file.
Specify the name and path of the file used to record ntpd's
process ID. This is the same operation as the pidfile pidfile
configuration file directive.
-P number, --priority=number
Process priority. This option takes an integer number as its
argument.
To the extent permitted by the operating system, run ntpd at the
specified sched_setscheduler(SCHED_FIFO) priority.
-q, --quit
Set the time and quit.
ntpd will exit just after the first time the clock is set. This
behavior mimics that of the ntpdate program, which is to be
retired. The -g and -x options can be used with this option.
Note: The kernel time discipline is disabled with this option.
-r string, --propagationdelay=string
Broadcast/propagation delay.
Specify the default propagation delay from the broadcast/multi-
cast server to this client. This is necessary only if the delay
cannot be computed automatically by the protocol.
--saveconfigquit=string
Save parsed configuration and quit.
Cause ntpd to parse its startup configuration file and save an
equivalent to the given filename and exit. This option was
designed for automated testing.
-s string, --statsdir=string
Statistics file location.
Specify the directory path for files created by the statistics
facility. This is the same operation as the statsdir statsdir
configuration file directive.
-t tkey, --trustedkey=tkey
Trusted key number. This option may appear an unlimited number
of times.
Add a key number to the trusted key list.
-u string, --user=string
Run as userid (or userid:groupid).
Specify a user, and optionally a group, to switch to. This
option is only available if the OS supports adjusting the clock
without full root privileges. This option is supported under
NetBSD (configure with --enable-clockctl ) and Linux (configure
with --enable-linuxcaps ).
-U number, --updateinterval=number
interval in seconds between scans for new or dropped interfaces.
This option takes an integer number as its argument.
Give the time in seconds between two scans for new or dropped
interfaces. For systems with routing socket support the scans
will be performed shortly after the interface change has been
detected by the system. Use 0 to disable scanning. 60 seconds
is the minimum time between scans.
--var=nvar
make ARG an ntp variable (RW). This option may appear an unlim-
ited number of times.
--dvar=ndvar
make ARG an ntp variable (RW|DEF). This option may appear an
unlimited number of times.
-x, --slew
Slew up to 600 seconds.
Normally, the time is slewed if the offset is less than the step
threshold, which is 128 ms by default, and stepped if above the
threshold. This option sets the threshold to 600 s, which is
well within the accuracy window to set the clock manually.
Note: Since the slew rate of typical Unix kernels is limited to
0.5 ms/s, each second of adjustment requires an amortization
interval of 2000 s. Thus, an adjustment as much as 600 s will
take almost 14 days to complete. This option can be used with
the -g and -q options. See the tinker configuration file direc-
tive for other options. Note: The kernel time discipline is
disabled with this option.
--usepcc
Use CPU cycle counter (Windows only).
Attempt to substitute the CPU counter for QueryPerformance-
Counter. The CPU counter and QueryPerformanceCounter are com-
pared, and if they have the same frequency, the CPU counter
(RDTSC on x86) is used directly, saving the overhead of a system
call.
--pccfreq=string
Force CPU cycle counter use (Windows only).
Force substitution the CPU counter for QueryPerformanceCounter.
The CPU counter (RDTSC on x86) is used unconditionally with the
given frequency (in Hz).
-?, --help
Display extended usage information and exit.
-!, --more-help
Extended usage information passed thru pager.
- [{v|c|n}], --version[={v|c|n}]
Output version of program and exit. The default mode is `v', a
simple version. The `c' mode will print copyright information
and `n' will print the full copyright notice.
OPTION PRESETS
Any option that is not marked as not presettable may be preset by load-
ing values from environment variables named:
NTPD_<option-name> or NTPD
AUTHOR
David L. Mills and/or others
Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
see html/copyright.html
This manual page was AutoGen-erated from the ntpd option definitions.
( 4.2.6) 2009-12-10 ntpd(1)
Mac OS X 10.7 - Generated Thu Aug 11 13:50:57 CDT 2011