2 .Dt SNTP 8 User Commands
4 .\" EDIT THIS FILE WITH CAUTION (sntp-opts.mdoc)
8 .\" It has been AutoGen-ed February 27, 2018 at 05:13:14 PM by AutoGen 5.18.5
9 .\" From the definitions sntp-opts.def
10 .\" and the template file agmdoc-cmd.tpl
13 .Nd standard Simple Network Time Protocol client program
16 .\" Mixture of short (flag) options and long options
18 .Op Fl flag Op Ar value
19 .Op Fl \-option\-name Ns Oo Oo Ns "=| " Oc Ns Ar value Oc
20 [ hostname\-or\-IP ...]
24 can be used as an SNTP client to query a NTP or SNTP server and either display
25 the time or set the local system's time (given suitable privilege). It can be
26 run as an interactive command or from a
29 NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol)
30 are defined and described by RFC 5905.
32 The default is to write the estimated correct local date and time (i.e. not
33 UTC) to the standard output in a format like:
34 .Ic "'1996\-10\-15 20:17:25.123 (+0800) +4.567 +/\- 0.089 [host] IP sN'"
37 means that to get to UTC from the reported local time one must
38 add 8 hours and 0 minutes,
41 indicates the local clock is 4.567 seconds behind the correct time
42 (so 4.567 seconds must be added to the local clock to get it to be correct).
43 Note that the number of decimals printed for this value will change
44 based on the reported precision of the server.
47 .Em synchronization distance
48 (in seconds), which represents the maximum error due to all causes.
49 If the server does not report valid data needed to calculate the
50 synchronization distance, this will be reported as
56 both will be displayed.
62 of the host is reported
63 and the leap indicator is decoded and displayed.
67 Force IPv4 DNS name resolution.
68 This option must not appear in combination with any of the following options:
71 Force DNS resolution of the following host names on the command line
72 to the IPv4 namespace.
74 Force IPv6 DNS name resolution.
75 This option must not appear in combination with any of the following options:
78 Force DNS resolution of the following host names on the command line
79 to the IPv6 namespace.
80 .It Fl a Ar auth\-keynumber , Fl \-authentication Ns = Ns Ar auth\-keynumber
81 Enable authentication with the key \fBauth\-keynumber\fP.
82 This option takes an integer number as its argument.
84 Enable authentication using the key specified in this option's
85 argument. The argument of this option is the \fBkeyid\fP, a
86 number specified in the \fBkeyfile\fP as this key's identifier.
87 See the \fBkeyfile\fP option (\fB\-k\fP) for more details.
88 .It Fl b Ar broadcast\-address , Fl \-broadcast Ns = Ns Ar broadcast\-address
89 Listen to the address specified for broadcast time sync.
90 This option may appear an unlimited number of times.
92 If specified \fBsntp\fP will listen to the specified address
93 for NTP broadcasts. The default maximum wait time
94 can (and probably should) be modified with \fB\-t\fP.
95 .It Fl c Ar host\-name , Fl \-concurrent Ns = Ns Ar host\-name
96 Concurrently query all IPs returned for host\-name.
97 This option may appear an unlimited number of times.
99 Requests from an NTP "client" to a "server" should never be sent
100 more rapidly than one every 2 seconds. By default, any IPs returned
101 as part of a DNS lookup are assumed to be for a single instance of
102 \fBntpd\fP, and therefore \fBsntp\fP will send queries to these IPs
103 one after another, with a 2\-second gap in between each query.
105 The \fB\-c\fP or \fB\-\-concurrent\fP flag says that any IPs
106 returned for the DNS lookup of the supplied host\-name are on
107 different machines, so we can send concurrent queries.
108 .It Fl d , Fl \-debug\-level
109 Increase debug verbosity level.
110 This option may appear an unlimited number of times.
112 .It Fl D Ar number , Fl \-set\-debug\-level Ns = Ns Ar number
113 Set the debug verbosity level.
114 This option may appear an unlimited number of times.
115 This option takes an integer number as its argument.
117 .It Fl g Ar milliseconds , Fl \-gap Ns = Ns Ar milliseconds
118 The gap (in milliseconds) between time requests.
119 This option takes an integer number as its argument.
126 Since we're only going to use the first valid response we get and
127 there is benefit to specifying a good number of servers to query,
128 separate the queries we send out by the specified number of
130 .It Fl K Ar file\-name , Fl \-kod Ns = Ns Ar file\-name
131 KoD history filename.
138 Specifies the filename to be used for the persistent history of KoD
139 responses received from servers. If the file does not exist, a
140 warning message will be displayed. The file will not be created.
141 .It Fl k Ar file\-name , Fl \-keyfile Ns = Ns Ar file\-name
142 Look in this file for the key specified with \fB\-a\fP.
149 This option specifies the keyfile.
150 \fBsntp\fP will search for the key specified with \fB\-a\fP
151 \fIkeyno\fP in this file. See \fBntp.keys(5)\fP for more
153 .It Fl l Ar file\-name , Fl \-logfile Ns = Ns Ar file\-name
154 Log to specified logfile.
156 This option causes the client to write log messages to the specified
158 .It Fl M Ar number , Fl \-steplimit Ns = Ns Ar number
159 Adjustments less than \fBsteplimit\fP msec will be slewed.
160 This option takes an integer number as its argument.
163 is constrained to being:
167 greater than or equal to 0
171 If the time adjustment is less than \fIsteplimit\fP milliseconds,
172 slew the amount using \fBadjtime(2)\fP. Otherwise, step the
173 correction using \fBsettimeofday(2)\fP. The default value is 0,
174 which means all adjustments will be stepped. This is a feature, as
175 different situations demand different values.
176 .It Fl o Ar number , Fl \-ntpversion Ns = Ns Ar number
177 Send \fBint\fP as our NTP protocol version.
178 This option takes an integer number as its argument.
181 is constrained to being:
185 in the range 0 through 7
194 When sending requests to a remote server, tell them we are running
195 NTP protocol version \fIntpversion\fP .
196 .It Fl r , Fl \-usereservedport
197 Use the NTP Reserved Port (port 123).
199 Use port 123, which is reserved for NTP, for our network
202 OK to 'step' the time with \fBsettimeofday(2)\fP.
205 OK to 'slew' the time with \fBadjtime(2)\fP.
207 .It Fl t Ar seconds , Fl \-timeout Ns = Ns Ar seconds
208 The number of seconds to wait for responses.
209 This option takes an integer number as its argument.
216 When waiting for a reply, \fBsntp\fP will wait the number
217 of seconds specified before giving up. The default should be
218 more than enough for a unicast response. If \fBsntp\fP is
219 only waiting for a broadcast response a longer timeout is
221 .It Fl \-wait , Fl \-no\-wait
222 Wait for pending replies (if not setting the time).
223 The \fIno\-wait\fP form will disable the option.
224 This option is enabled by default.
226 If we are not setting the time, wait for all pending responses.
227 .It Fl \&? , Fl \-help
228 Display usage information and exit.
229 .It Fl \&! , Fl \-more\-help
230 Pass the extended usage information through a pager.
231 .It Fl > Oo Ar cfgfile Oc , Fl \-save\-opts Oo Ns = Ns Ar cfgfile Oc
232 Save the option state to \fIcfgfile\fP. The default is the \fIlast\fP
233 configuration file listed in the \fBOPTION PRESETS\fP section, below.
234 The command will exit after updating the config file.
235 .It Fl < Ar cfgfile , Fl \-load\-opts Ns = Ns Ar cfgfile , Fl \-no\-load\-opts
236 Load options from \fIcfgfile\fP.
237 The \fIno\-load\-opts\fP form will disable the loading
238 of earlier config/rc/ini files. \fI\-\-no\-load\-opts\fP is handled early,
240 .It Fl \-version Op Brq Ar v|c|n
241 Output version of program and exit. The default mode is `v', a simple
242 version. The `c' mode will print copyright information and `n' will
243 print the full copyright notice.
246 Any option that is not marked as \fInot presettable\fP may be preset
247 by loading values from configuration ("RC" or ".INI") file(s) and values from
248 environment variables named:
250 \fBSNTP_<option\-name>\fP or \fBSNTP\fP
253 The environmental presets take precedence (are processed later than)
254 the configuration files.
255 The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP".
256 If any of these are directories, then the file \fI.ntprc\fP
257 is searched for within those directories.
259 .Bl -tag -width indent
260 .It Li "sntp ntpserver.somewhere"
261 is the simplest use of this program
262 and can be run as an unprivileged command
263 to check the current time and error in the local clock.
264 .It Li "sntp \-Ss \-M 128 ntpserver.somewhere"
265 With suitable privilege,
270 .Ic "sntp \-Ss \-M 128 ntpserver.somewhere"
271 will request the time from the server,
272 and if that server reports that it is synchronized
273 then if the offset adjustment is less than 128 milliseconds
274 the correction will be slewed,
275 and if the correction is more than 128 milliseconds
276 the correction will be stepped.
277 .It Li "sntp \-S ntpserver.somewhere"
278 With suitable privilege,
283 .Ic "sntp \-S ntpserver.somewhere"
284 will set (step) the local clock from a synchronized specified server,
285 like the (deprecated)
292 See \fBOPTION PRESETS\fP for configuration environment variables.
294 See \fBOPTION PRESETS\fP for configuration files.
296 One of the following exit values will be returned:
298 .It 0 " (EXIT_SUCCESS)"
299 Successful program execution.
300 .It 1 " (EXIT_FAILURE)"
301 The operation failed or the command syntax was not valid.
302 .It 66 " (EX_NOINPUT)"
303 A specified configuration file could not be loaded.
304 .It 70 " (EX_SOFTWARE)"
305 libopts had an internal operational error. Please report
306 it to autogen\-users@lists.sourceforge.net. Thank you.
309 .An "Johannes Maximilian Kuehn"
313 Copyright (C) 1992\-2017 The University of Delaware and Network Time Foundation all rights reserved.
314 This program is released under the terms of the NTP license, <http://ntp.org/license>.
316 Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
318 This manual page was \fIAutoGen\fP\-erated from the \fBsntp\fP