NAME
 sntp — standard Simple Network Time Protocol client program
SYNOPSIS
| sntp | [-flags] [-flag [value]] [--option-name[[=| ]value]] [ hostname-or-IP ...] | 
 
DESCRIPTION
 sntp can be used as an SNTP client to query a NTP or SNTP server and either display the time or set the local system's time (given suitable privilege).  It can be run as an interactive command or from a 
cron job. NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol) are defined and described by RFC 5905.
The default is to write the estimated correct local date and time (i.e. not UTC) to the standard output in a format like: '1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN' where the '(+0800)' means that to get to UTC from the reported local time one must add 8 hours and 0 minutes, the '+4.567' indicates the local clock is 4.567 seconds behind the correct time (so 4.567 seconds must be added to the local clock to get it to be correct). Note that the number of decimals printed for this value will change based on the reported precision of the server. '+/- 0.089' is the reported synchronization distance (in seconds), which represents the maximum error due to all causes. If the server does not report valid data needed to calculate the synchronization distance, this will be reported as '+/- ?'. If the host is different from the IP, both will be displayed. Otherwise, only the IP is displayed. Finally, the stratum of the host is reported.
 
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 the 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 the following host names on the command line to the IPv6 namespace.
- 
-a auth-keynumber, --authentication=auth-keynumber
- 
Enable authentication with the key auth-keynumber. This option takes an integer number as its argument.
  Enable authentication using the key specified in this option's argument.  The argument of this option is the  keyid, a number specified in the  keyfile as this key's identifier. See the  keyfile option (-k) for more details.
- 
-b broadcast-address, --broadcast=broadcast-address
- 
Listen to the address specified for broadcast time sync. This option may appear an unlimited number of times.
  If specified sntp will listen to the specified address for NTP broadcasts.  The default maximum wait time can (and probably should) be modified with  -t.
- 
-c host-name, --concurrent=host-name
- 
Concurrently query all IPs returned for host-name. This option may appear an unlimited number of times.
  Requests from an NTP "client" to a "server" should never be sent more rapidly than one every 2 seconds.  By default, any IPs returned as part of a DNS lookup are assumed to be for a single instance of  ntpd, and therefore sntp will send queries to these IPs one after another, with a 2-second gap in between each query.
  The -c or --concurrent flag says that any IPs returned for the DNS lookup of the supplied host-name are on different machines, so we can send concurrent queries.
- 
-d, --debug-level
- 
Increase debug verbosity level. This option may appear an unlimited number of times.
  
- 
-D number, --set-debug-level=number
- 
Set the debug verbosity level. This option may appear an unlimited number of times. This option takes an integer number as its argument.
  
- 
-g milliseconds, --gap=milliseconds
- 
The gap (in milliseconds) between time requests. This option takes an integer number as its argument. The default milliseconds for this option is:
 50
  Since we're only going to use the first valid response we get and there is benefit to specifying a good number of servers to query, separate the queries we send out by the specified number of milliseconds.
- 
-K file-name, --kod=file-name
- 
KoD history filename. The default file-name for this option is:
 /var/db/ntp-kod
  Specifies the filename to be used for the persistent history of KoD responses received from servers.
- 
-k file-name, --keyfile=file-name
- 
Look in this file for the key specified with -a.
  This option specifies the keyfile.  sntp will search for the key specified with -a  keyno in this file.  See ntp.keys(5) for more information.
- 
-l file-name, --logfile=file-name
- 
Log to specified logfile.
  This option causes the client to write log messages to the specified  logfile.
- 
-M number, --steplimit=number
- 
Adjustments less than steplimit msec will be slewed. This option takes an integer number as its argument. The value of number is constrained to being: greater than or equal to 0
  If the time adjustment is less than steplimit milliseconds, slew the amount using  adjtime(2).  Otherwise, step the correction using  settimeofday(2).
- 
-o number, --ntpversion=number
- 
Send int as our NTP protocol version. This option takes an integer number as its argument. The value of number is constrained to being: in the range  0 through 7 The default number for this option is:
 4
  When sending requests to a remote server, tell them we are running NTP protocol version  ntpversion .
- 
-r, --usereservedport
- 
Use the NTP Reserved Port (port 123).
  Use port 123, which is reserved for NTP, for our network communications.
- 
-S, --step
- 
OK to 'step' the time with settimeofday(2).
  
- 
-s, --slew
- 
OK to 'slew' the time with adjtime(2).
  
- 
-t seconds, --timeout=seconds
- 
The number of seconds to wait for responses. This option takes an integer number as its argument. The default seconds for this option is:
 5
  When waiting for a reply, sntp will wait the number of seconds specified before giving up.  The default should be more than enough for a unicast response.  If  sntp is only waiting for a broadcast response a longer timeout is likely needed.
- 
--wait, - Fl -no-wait
- 
Wait for pending replies (if not setting the time). The  no-wait form will disable the option. This option is enabled by default.
  If we are not setting the time, wait for all pending responses.
- 
-?, --help
- 
Display usage information and exit.
- 
-!, --more-help
- 
Pass the extended usage information through a pager.
- 
-> [cfgfile], --save-opts [=cfgfile]
- 
Save the option state to cfgfile.  The default is the last configuration file listed in the  OPTION PRESETS section, below. The command will exit after updating the config file.
- 
-< cfgfile, --load-opts=cfgfile, --no-load-opts
- 
Load options from cfgfile. The  no-load-opts form will disable the loading of earlier config/rc/ini files.   --no-load-opts is handled early, out of order.
- 
--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 loading values from configuration ("RC" or ".INI") file(s) and values from environment variables named:
  SNTP_<option-name> or SNTP The environmental presets take precedence (are processed later than) the configuration files. The  homerc files are "$HOME", and ".". If any of these are directories, then the file  .ntprc is searched for within those directories. cvt_prog='/usr/local/gnu/share/autogen/texi2mdoc' cvt_prog=`cd ̀dirname "$cvt_prog"̀ >/dev/null && pwd
         `/`basename "$cvt_prog"` cd $tmp_dir test -x "$cvt_prog" || die "'$cvt_prog' is not executable" {
    list='synopsis description options option-presets'
    for f in $list ; do cat $f ; echo ; done
    rm -f $list name
    list='implementation-notes environment files examples exit-status errors
        compatibility see-also conforming-to history authors copyright bugs
        notes'
    for f in $list ; do cat $f ; echo ; done > .end-doc
    rm -f $list
    list=`ls -1 *`' .end-doc'
    for f in $list ; do cat $f ; echo ; done
    rm -f $list } 1>.doc 2>/dev/null sed -f .cmds .doc | /usr/local/gnu/bin/grep -E -v '^[ 	]*$' | $cvt_prog
USAGE
- 
sntp ntpserver.somewhere
- 
is the simplest use of this program and can be run as an unprivileged command to check the current time and error in the local clock.
- 
sntp -a ntpserver.somewhere
- 
With suitable privilege, run as a command or from a cron(8) job, sntp -a will reset the local clock from a synchronized specified server, like the (deprecated) ntpdate(8), or rdate(8) commands.
 
ENVIRONMENT
 See  OPTION PRESETS for configuration environment variables.
FILES
 See  OPTION PRESETS for configuration files.
EXIT STATUS
 One of the following exit values will be returned:
- 
0  (EXIT_SUCCESS)
- 
Successful program execution.
- 
1  (EXIT_FAILURE)
- 
The operation failed or the command syntax was not valid.
- 
66  (EX_NOINPUT)
- 
A specified configuration file could not be loaded.
- 
70  (EX_SOFTWARE)
- 
libopts had an internal operational error.  Please report it to autogen-users@lists.sourceforge.net.  Thank you.
 
AUTHORS
 Johannes Maximilian Kuehn Harlan Stenn Dave Hart
COPYRIGHT
 Copyright (C) 1970-2013 The University of Delaware all rights reserved. This program is released under the terms of the NTP license, <http://ntp.org/license>.
BUGS
 Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
NOTES
 This document corresponds to version 4.2.7p404 of 
sntp.
This manual page was AutoGen-erated from the sntp option definitions.