ntpdate4(1M) System Administration Commands ntpdate4(1M)NAMEntpdate4 - set the date and time with NTP
SYNOPSIS
/usr/sbin/ntpdate4 [-46bBdqsuv] [-a key] [-e Authdelay] [-k keyfile]
[-o version] [-p samples] [-t timeout] server [ ... ]
OPTIONS-4 Force DNS resolution of following host names on the command line
to the IPv4 namespace.
-6 Force DNS resolution of following host names on the command line
to the IPv6 namespace.
-a key Enable authentication and specify the key identifier to be used
for authentication as the argument key. The keys and key identi‐
fiers must match in both the client and server key files. The
default is to disable authentication.
-B Force the time to always be slewed using the adjtime() system
call, even if the measured offset is greater than 0.5 seconds.
The default is to step the time using settimeofday() if the off‐
set is greater than +-0.5s. Note that, if the offset is much
greater than +-0.5s in this case, that it can take a long time
(hours) to slew the clock to the correct value. During this
time, the host should not be used to synchronize clients.
-b Force the time to be stepped using the settimeofday() system
call, rather than slewed (default) using the adjtime() system
call. This option should be used when called from a startup file
at boot time.
-d Enable the debugging mode, in which ntpdate4 will go through all
the steps, but not adjust the local clock. Information useful
for general debugging will also be printed.
-e authdelay
Specify the processing delay to perform an authentication func‐
tion as the value authdelay, in seconds and fraction (see ntpd
for details). This number is usually small enough to be negligi‐
ble for most purposes, though specifying a value may improve
timekeeping on very slow CPU's.
-k keyfile
Specify the path for the authentication key file as the string
keyfile. The default is /etc/inet/ntp.keys. This file should be
in the format described in ntpd.
-o version
Specify the NTP version for outgoing packets as the integer ver‐
sion, which can be 1 or 2. The default is 3. This allows ntp‐
date4 to be used with older NTP versions.
-p samples
Specify the number of samples to be acquired from each server as
the integer samples, with values from 1 to 8 inclusive. The
default is 4.
-q Query only - don't set the clock.
-s Divert logging output from the standard output (default) to the
system syslog facility.
-t timeout
Specify the maximum time waiting for a server response as the
value timeout, in seconds and fraction. The value is is rounded
to a multiple of 0.2 seconds. The default is 1 second, a value
suitable for polling across a LAN.
-u Direct ntpdate4 to use an unprivileged port or outgoing packets.
This is most useful when behind a firewall that blocks incoming
traffic to privileged ports, and you want to synchronise with
hosts beyond the firewall. Note that the -d option always uses
unprivileged ports.
-v Print ntpdate4's version identification string during program
startup.
DESCRIPTIONntpdate4 sets the local date and time by polling the Network Time Pro‐
tocol (NTP) server(s) given as the server arguments to determine the
correct time. It must be run as root unless the -d or -q options are
used. A number of samples are obtained from each of the servers speci‐
fied and a subset of the NTP clock filter and selection algorithms are
applied to select the best of these. Note that the accuracy and relia‐
bility of ntpdate4 depends on the number of servers, the number of
polls each time it is run and the interval between runs.
ntpdate4 can be run manually as necessary to set the host clock, or it
can be run from the host startup script to set the clock at boot time.
It is also possible to run ntpdate4 from a cron script. However, it is
important to note that ntpdate4 with contrived cron scripts is no sub‐
stitute for the NTP daemon, which uses sophisticated algorithms to max‐
imize accuracy and reliability while minimizing resource use. Finally,
since ntpdate4 does not discipline the host clock frequency as does
ntpd, the accuracy using ntpdate4 is limited.
Time adjustments are made by ntpdate4 in one of two ways. If ntpdate4
determines the clock is in error more than 0.5 second it will simply
step the time by calling the system settimeofday() routine. If the
error is less than 0.5 seconds, it will slew the time by calling the
system adjtime() routine. The latter technique is less disruptive and
more accurate when the error is small, and works quite well when ntp‐
date4 is run by cron every hour or two. ntpdate4 will decline to set
the date if an NTP server daemon (e.g., ntpd) is running on the same
host. When running ntpdate4 on a regular basis from cron as an alterna‐
tive to running a daemon, doing so once every hour or two will result
in precise enough timekeeping to avoid stepping the clock. Note that
in contexts where a host name is expected, a -4 qualifier preceding the
host name forces DNS resolution to the IPv4 namespace, while a -6 qual‐
ifier forces DNS resolution to the IPv6 namespace.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬──────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼──────────────────────┤
│Availability │ SUNWntp4u │
├────────────────────┼──────────────────────┤
│Interface Stability │ Uncommitted Obsolete │
└────────────────────┴──────────────────────┘
NOTES
Source for ntpdate4 is available in the SUNWntp4S package.
Disclaimer: The functionality of this program is now available in the
ntpd program. See the -q command line option in the ntpd - Network Time
Protocol (NTP) daemon man page. After a suitable period, the ntpdate4
program is to be retired from this distribution
The package name that delivers this program will be changed in the next
release and should not be relied on. The name of this program will also
change at that time, and should not be relied on.
SEE ALSOntpd(1M), ntpdc(1M), attributes(5)ntpdate4(1M)
