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22 <h1 class="settitle">Sntp User's Manual</h1>
23 <div class="node">
24 <p><hr>
25 <a name="Top"></a>Next: <a rel="next" accesskey="n" href="#sntp-Description">sntp Description</a>,
26 Previous: <a rel="previous" accesskey="p" href="#dir">(dir)</a>,
27 Up: <a rel="up" accesskey="u" href="#dir">(dir)</a>
28 <br>
29 </div>
30
31 <h2 class="unnumbered">Simple Network Time Protocol User Manual</h2>
32
33 <p>This document describes the use of the NTP Project's <code>sntp</code> program,
34 that can be used to query a Network Time Protocol (NTP) server and
35 display the time offset of the system clock relative to the server
36 clock. Run as root, it can correct the system clock to this offset as
37 well. It can be run as an interactive command or from a cron job.
38
39 <p>This document applies to version 4.2.8 of <code>sntp</code>.
40
41 <p>The program implements the SNTP protocol as defined by RFC 5905, the NTPv4
42 IETF specification.
43
44 <div class="shortcontents">
45 <h2>Short Contents</h2>
46 <ul>
47 <a href="#Top">Simple Network Time Protocol User Manual</a>
48 </ul>
49 </div>
50
51 <ul class="menu">
52 <li><a accesskey="1" href="#sntp-Description">sntp Description</a>: Description
53 <li><a accesskey="2" href="#sntp-Invocation">sntp Invocation</a>: Invoking sntp
54 <li><a accesskey="3" href="#Usage">Usage</a>: Usage
55 </ul>
56
57 <div class="node">
58 <p><hr>
59 <a name="sntp-Description"></a>
60 <br>
61 </div>
62
63 <!-- node-name, next, previous, up -->
64 <h3 class="section">Description</h3>
65
66 <p>By default, <code>sntp</code> writes the local data and time (i.e., not UTC) to the
67 standard output in the format:
68
69 <pre class="example"> 1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
70 </pre>
71 <p>where
72 YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time,
73 (+0800) is the local timezone adjustment (so we would add 8 hours and 0 minutes to convert the reported local time to UTC),
74 and
75 the +4.567 +/- 0.089 secs indicates the time offset and
76 error bound of the system clock relative to the server clock.
77
78 <div class="node">
79 <p><hr>
80 <a name="sntp-Invocation"></a>
81 <br>
82 </div>
83
84 <h3 class="section">Invoking sntp</h3>
85
86 <p><a name="index-sntp-1"></a><a name="index-standard-Simple-Network-Time-Protocol-client-program-2"></a>
87
88 <p><code>sntp</code>
89 can be used as an SNTP client to query a NTP or SNTP server and either display
90 the time or set the local system's time (given suitable privilege). It can be
91 run as an interactive command or from a
92 <code>cron</code>
93 job.
94
95 <p>NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol)
96 are defined and described by RFC 5905.
97
98 <p>The default is to write the estimated correct local date and time (i.e. not
99 UTC) to the standard output in a format like:
100
101 <p><code>'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN'</code>
102
103 <p>where the
104 <code>'(+0800)'</code>
105 means that to get to UTC from the reported local time one must
106 add 8 hours and 0 minutes,
107 the
108 <code>'+4.567'</code>
109 indicates the local clock is 4.567 seconds behind the correct time
110 (so 4.567 seconds must be added to the local clock to get it to be correct).
111 Note that the number of decimals printed for this value will change
112 based on the reported precision of the server.
113 <code>'+/- 0.089'</code>
114 is the reported
115 <em>synchronization</em> <em>distance</em>
116 (in seconds), which represents the maximum error due to all causes.
117 If the server does not report valid data needed to calculate the
118 synchronization distance, this will be reported as
119 <code>'+/- ?'</code>.
120 If the
121 <em>host</em>
122 is different from the
123 <em>IP</em>,
124 both will be displayed.
125 Otherwise, only the
126 <em>IP</em>
127 is displayed.
128 Finally, the
129 <em>stratum</em>
130 of the host is reported.
131
132 <p>This section was generated by <strong>AutoGen</strong>,
133 using the <code>agtexi-cmd</code> template and the option descriptions for the <code>sntp</code> program.
134 This software is released under the NTP license, <http://ntp.org/license>.
135
136 <ul class="menu">
137 <li><a accesskey="1" href="#sntp-usage">sntp usage</a>: sntp help/usage (<span class="option">--help</span>)
138 <li><a accesskey="2" href="#sntp-ipv4">sntp ipv4</a>: ipv4 option (-4)
139 <li><a accesskey="3" href="#sntp-ipv6">sntp ipv6</a>: ipv6 option (-6)
140 <li><a accesskey="4" href="#sntp-authentication">sntp authentication</a>: authentication option (-a)
141 <li><a accesskey="5" href="#sntp-broadcast">sntp broadcast</a>: broadcast option (-b)
142 <li><a accesskey="6" href="#sntp-concurrent">sntp concurrent</a>: concurrent option (-c)
143 <li><a accesskey="7" href="#sntp-gap">sntp gap</a>: gap option (-g)
144 <li><a accesskey="8" href="#sntp-kod">sntp kod</a>: kod option (-K)
145 <li><a accesskey="9" href="#sntp-keyfile">sntp keyfile</a>: keyfile option (-k)
146 <li><a href="#sntp-logfile">sntp logfile</a>: logfile option (-l)
147 <li><a href="#sntp-steplimit">sntp steplimit</a>: steplimit option (-M)
148 <li><a href="#sntp-ntpversion">sntp ntpversion</a>: ntpversion option (-o)
149 <li><a href="#sntp-usereservedport">sntp usereservedport</a>: usereservedport option (-r)
150 <li><a href="#sntp-timeout">sntp timeout</a>: timeout option (-t)
151 <li><a href="#sntp-wait">sntp wait</a>: wait option
152 <li><a href="#sntp-config">sntp config</a>: presetting/configuring sntp
153 <li><a href="#sntp-exit-status">sntp exit status</a>: exit status
154 <li><a href="#sntp-Usage">sntp Usage</a>: Usage
155 <li><a href="#sntp-Authors">sntp Authors</a>: Authors
156 </ul>
157
158 <div class="node">
159 <p><hr>
160 <a name="sntp-usage"></a>Next: <a rel="next" accesskey="n" href="#sntp-ipv4">sntp ipv4</a>,
161 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
162 <br>
163 </div>
164
165 <h4 class="subsection">sntp help/usage (<span class="option">--help</span>)</h4>
166
167 <p><a name="index-sntp-help-3"></a>
168 This is the automatically generated usage text for sntp.
169
170 <p>The text printed is the same whether selected with the <code>help</code> option
171 (<span class="option">--help</span>) or the <code>more-help</code> option (<span class="option">--more-help</span>). <code>more-help</code> will print
172 the usage text by passing it through a pager program.
173 <code>more-help</code> is disabled on platforms without a working
174 <code>fork(2)</code> function. The <code>PAGER</code> environment variable is
175 used to select the program, defaulting to <span class="file">more</span>. Both will exit
176 with a status code of 0.
177
178 <pre class="example">sntp - standard Simple Network Time Protocol client program - Ver. 4.2.8
179 Usage: sntp [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \
180 [ hostname-or-IP ...]
181 Flg Arg Option-Name Description
182 -4 no ipv4 Force IPv4 DNS name resolution
183 - prohibits the option 'ipv6'
184 -6 no ipv6 Force IPv6 DNS name resolution
185 - prohibits the option 'ipv4'
186 -a Num authentication Enable authentication with the key auth-keynumber
187 -b Str broadcast Listen to the address specified for broadcast time sync
188 - may appear multiple times
189 -c Str concurrent Concurrently query all IPs returned for host-name
190 - may appear multiple times
191 -d no debug-level Increase debug verbosity level
192 - may appear multiple times
193 -D Num set-debug-level Set the debug verbosity level
194 - may appear multiple times
195 -g Num gap The gap (in milliseconds) between time requests
196 -K Fil kod KoD history filename
197 -k Fil keyfile Look in this file for the key specified with -a
198 -l Fil logfile Log to specified logfile
199 -M Num steplimit Adjustments less than steplimit msec will be slewed
200 - it must be in the range:
201 greater than or equal to 0
202 -o Num ntpversion Send int as our NTP protocol version
203 - it must be in the range:
204 0 to 7
205 -r no usereservedport Use the NTP Reserved Port (port 123)
206 -S no step OK to 'step' the time with settimeofday(2)
207 -s no slew OK to 'slew' the time with adjtime(2)
208 -t Num timeout The number of seconds to wait for responses
209 no wait Wait for pending replies (if not setting the time)
210 - disabled as '--no-wait'
211 - enabled by default
212 opt version output version information and exit
213 -? no help display extended usage information and exit
214 -! no more-help extended usage information passed thru pager
215 -> opt save-opts save the option state to a config file
216 -< Str load-opts load options from a config file
217 - disabled as '--no-load-opts'
218 - may appear multiple times
219
220 Options are specified by doubled hyphens and their name or by a single
221 hyphen and the flag character.
222
223
224 The following option preset mechanisms are supported:
225 - reading file $HOME/.ntprc
226 - reading file ./.ntprc
227 - examining environment variables named SNTP_*
228
229 Please send bug reports to: <http://bugs.ntp.org, bugs (a] ntp.org>
230 </pre>
231 <div class="node">
232 <p><hr>
233 <a name="sntp-ipv4"></a>Next: <a rel="next" accesskey="n" href="#sntp-ipv6">sntp ipv6</a>,
234 Previous: <a rel="previous" accesskey="p" href="#sntp-usage">sntp usage</a>,
235 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
236 <br>
237 </div>
238
239 <h4 class="subsection">ipv4 option (-4)</h4>
240
241 <p><a name="index-sntp_002dipv4-4"></a>
242 This is the “force ipv4 dns name resolution” option.
243
244 <p class="noindent">This option has some usage constraints. It:
245 <ul>
246 <li>must not appear in combination with any of the following options:
247 ipv6.
248 </ul>
249
250 <p>Force DNS resolution of the following host names on the command line
251 to the IPv4 namespace.
252 <div class="node">
253 <p><hr>
254 <a name="sntp-ipv6"></a>Next: <a rel="next" accesskey="n" href="#sntp-authentication">sntp authentication</a>,
255 Previous: <a rel="previous" accesskey="p" href="#sntp-ipv4">sntp ipv4</a>,
256 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
257 <br>
258 </div>
259
260 <h4 class="subsection">ipv6 option (-6)</h4>
261
262 <p><a name="index-sntp_002dipv6-5"></a>
263 This is the “force ipv6 dns name resolution” option.
264
265 <p class="noindent">This option has some usage constraints. It:
266 <ul>
267 <li>must not appear in combination with any of the following options:
268 ipv4.
269 </ul>
270
271 <p>Force DNS resolution of the following host names on the command line
272 to the IPv6 namespace.
273 <div class="node">
274 <p><hr>
275 <a name="sntp-authentication"></a>Next: <a rel="next" accesskey="n" href="#sntp-broadcast">sntp broadcast</a>,
276 Previous: <a rel="previous" accesskey="p" href="#sntp-ipv6">sntp ipv6</a>,
277 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
278 <br>
279 </div>
280
281 <h4 class="subsection">authentication option (-a)</h4>
282
283 <p><a name="index-sntp_002dauthentication-6"></a>
284 This is the “enable authentication with the key <var>auth-keynumber</var>” option.
285 This option takes a number argument <span class="file">auth-keynumber</span>.
286 Enable authentication using the key specified in this option's
287 argument. The argument of this option is the <span class="option">keyid</span>, a
288 number specified in the <span class="option">keyfile</span> as this key's identifier.
289 See the <span class="option">keyfile</span> option (<span class="option">-k</span>) for more details.
290 <div class="node">
291 <p><hr>
292 <a name="sntp-broadcast"></a>Next: <a rel="next" accesskey="n" href="#sntp-concurrent">sntp concurrent</a>,
293 Previous: <a rel="previous" accesskey="p" href="#sntp-authentication">sntp authentication</a>,
294 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
295 <br>
296 </div>
297
298 <h4 class="subsection">broadcast option (-b)</h4>
299
300 <p><a name="index-sntp_002dbroadcast-7"></a>
301 This is the “listen to the address specified for broadcast time sync” option.
302 This option takes a string argument <span class="file">broadcast-address</span>.
303
304 <p class="noindent">This option has some usage constraints. It:
305 <ul>
306 <li>may appear an unlimited number of times.
307 </ul>
308
309 <p>If specified <code>sntp</code> will listen to the specified address
310 for NTP broadcasts. The default maximum wait time
311 can (and probably should) be modified with <span class="option">-t</span>.
312 <div class="node">
313 <p><hr>
314 <a name="sntp-concurrent"></a>Next: <a rel="next" accesskey="n" href="#sntp-gap">sntp gap</a>,
315 Previous: <a rel="previous" accesskey="p" href="#sntp-broadcast">sntp broadcast</a>,
316 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
317 <br>
318 </div>
319
320 <h4 class="subsection">concurrent option (-c)</h4>
321
322 <p><a name="index-sntp_002dconcurrent-8"></a>
323 This is the “concurrently query all ips returned for host-name” option.
324 This option takes a string argument <span class="file">host-name</span>.
325
326 <p class="noindent">This option has some usage constraints. It:
327 <ul>
328 <li>may appear an unlimited number of times.
329 </ul>
330
331 <p>Requests from an NTP "client" to a "server" should never be sent
332 more rapidly than one every 2 seconds. By default, any IPs returned
333 as part of a DNS lookup are assumed to be for a single instance of
334 <code>ntpd</code>, and therefore <code>sntp</code> will send queries to these IPs
335 one after another, with a 2-second gap in between each query.
336
337 <p>The <span class="option">-c</span> or <span class="option">--concurrent</span> flag says that any IPs
338 returned for the DNS lookup of the supplied host-name are on
339 different machines, so we can send concurrent queries.
340 <div class="node">
341 <p><hr>
342 <a name="sntp-gap"></a>Next: <a rel="next" accesskey="n" href="#sntp-kod">sntp kod</a>,
343 Previous: <a rel="previous" accesskey="p" href="#sntp-concurrent">sntp concurrent</a>,
344 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
345 <br>
346 </div>
347
348 <h4 class="subsection">gap option (-g)</h4>
349
350 <p><a name="index-sntp_002dgap-9"></a>
351 This is the “the gap (in milliseconds) between time requests” option.
352 This option takes a number argument <span class="file">milliseconds</span>.
353 Since we're only going to use the first valid response we get and
354 there is benefit to specifying a good number of servers to query,
355 separate the queries we send out by the specified number of
356 milliseconds.
357 <div class="node">
358 <p><hr>
359 <a name="sntp-kod"></a>Next: <a rel="next" accesskey="n" href="#sntp-keyfile">sntp keyfile</a>,
360 Previous: <a rel="previous" accesskey="p" href="#sntp-gap">sntp gap</a>,
361 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
362 <br>
363 </div>
364
365 <h4 class="subsection">kod option (-K)</h4>
366
367 <p><a name="index-sntp_002dkod-10"></a>
368 This is the “kod history filename” option.
369 This option takes a file argument <span class="file">file-name</span>.
370 Specifies the filename to be used for the persistent history of KoD
371 responses received from servers. If the file does not exist, a
372 warning message will be displayed. The file will not be created.
373 <div class="node">
374 <p><hr>
375 <a name="sntp-keyfile"></a>Next: <a rel="next" accesskey="n" href="#sntp-logfile">sntp logfile</a>,
376 Previous: <a rel="previous" accesskey="p" href="#sntp-kod">sntp kod</a>,
377 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
378 <br>
379 </div>
380
381 <h4 class="subsection">keyfile option (-k)</h4>
382
383 <p><a name="index-sntp_002dkeyfile-11"></a>
384 This is the “look in this file for the key specified with <span class="option">-a</span>” option.
385 This option takes a file argument <span class="file">file-name</span>.
386 This option specifies the keyfile.
387 <code>sntp</code> will search for the key specified with <span class="option">-a</span>
388 <span class="file">keyno</span> in this file. See <span class="command">ntp.keys(5)</span> for more
389 information.
390 <div class="node">
391 <p><hr>
392 <a name="sntp-logfile"></a>Next: <a rel="next" accesskey="n" href="#sntp-steplimit">sntp steplimit</a>,
393 Previous: <a rel="previous" accesskey="p" href="#sntp-keyfile">sntp keyfile</a>,
394 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
395 <br>
396 </div>
397
398 <h4 class="subsection">logfile option (-l)</h4>
399
400 <p><a name="index-sntp_002dlogfile-12"></a>
401 This is the “log to specified logfile” option.
402 This option takes a file argument <span class="file">file-name</span>.
403 This option causes the client to write log messages to the specified
404 <span class="file">logfile</span>.
405 <div class="node">
406 <p><hr>
407 <a name="sntp-steplimit"></a>Next: <a rel="next" accesskey="n" href="#sntp-ntpversion">sntp ntpversion</a>,
408 Previous: <a rel="previous" accesskey="p" href="#sntp-logfile">sntp logfile</a>,
409 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
410 <br>
411 </div>
412
413 <h4 class="subsection">steplimit option (-M)</h4>
414
415 <p><a name="index-sntp_002dsteplimit-13"></a>
416 This is the “adjustments less than <var>steplimit</var> msec will be slewed” option.
417 This option takes a number argument.
418 If the time adjustment is less than <span class="file">steplimit</span> milliseconds,
419 slew the amount using <span class="command">adjtime(2)</span>. Otherwise, step the
420 correction using <span class="command">settimeofday(2)</span>.
421 <div class="node">
422 <p><hr>
423 <a name="sntp-ntpversion"></a>Next: <a rel="next" accesskey="n" href="#sntp-usereservedport">sntp usereservedport</a>,
424 Previous: <a rel="previous" accesskey="p" href="#sntp-steplimit">sntp steplimit</a>,
425 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
426 <br>
427 </div>
428
429 <h4 class="subsection">ntpversion option (-o)</h4>
430
431 <p><a name="index-sntp_002dntpversion-14"></a>
432 This is the “send <var>int</var> as our ntp protocol version” option.
433 This option takes a number argument.
434 When sending requests to a remote server, tell them we are running
435 NTP protocol version <span class="file">ntpversion</span> .
436 <div class="node">
437 <p><hr>
438 <a name="sntp-usereservedport"></a>Next: <a rel="next" accesskey="n" href="#sntp-timeout">sntp timeout</a>,
439 Previous: <a rel="previous" accesskey="p" href="#sntp-ntpversion">sntp ntpversion</a>,
440 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
441 <br>
442 </div>
443
444 <h4 class="subsection">usereservedport option (-r)</h4>
445
446 <p><a name="index-sntp_002dusereservedport-15"></a>
447 This is the “use the ntp reserved port (port 123)” option.
448 Use port 123, which is reserved for NTP, for our network
449 communications.
450 <div class="node">
451 <p><hr>
452 <a name="sntp-timeout"></a>Next: <a rel="next" accesskey="n" href="#sntp-wait">sntp wait</a>,
453 Previous: <a rel="previous" accesskey="p" href="#sntp-usereservedport">sntp usereservedport</a>,
454 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
455 <br>
456 </div>
457
458 <h4 class="subsection">timeout option (-t)</h4>
459
460 <p><a name="index-sntp_002dtimeout-16"></a>
461 This is the “the number of seconds to wait for responses” option.
462 This option takes a number argument <span class="file">seconds</span>.
463 When waiting for a reply, <code>sntp</code> will wait the number
464 of seconds specified before giving up. The default should be
465 more than enough for a unicast response. If <code>sntp</code> is
466 only waiting for a broadcast response a longer timeout is
467 likely needed.
468 <div class="node">
469 <p><hr>
470 <a name="sntp-wait"></a>Next: <a rel="next" accesskey="n" href="#sntp-config">sntp config</a>,
471 Previous: <a rel="previous" accesskey="p" href="#sntp-timeout">sntp timeout</a>,
472 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
473 <br>
474 </div>
475
476 <h4 class="subsection">wait option</h4>
477
478 <p><a name="index-sntp_002dwait-17"></a>
479 This is the “wait for pending replies (if not setting the time)” option.
480
481 <p class="noindent">This option has some usage constraints. It:
482 <ul>
483 <li>can be disabled with –no-wait.
484 <li>It is enabled by default.
485 </ul>
486
487 <p>If we are not setting the time, wait for all pending responses.
488
489 <div class="node">
490 <p><hr>
491 <a name="sntp-config"></a>Next: <a rel="next" accesskey="n" href="#sntp-exit-status">sntp exit status</a>,
492 Previous: <a rel="previous" accesskey="p" href="#sntp-wait">sntp wait</a>,
493 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
494 <br>
495 </div>
496
497 <h4 class="subsection">presetting/configuring sntp</h4>
498
499 <p>Any option that is not marked as <i>not presettable</i> may be preset by
500 loading values from configuration ("rc" or "ini") files, and values from environment variables named <code>SNTP</code> and <code>SNTP_<OPTION_NAME></code>. <code><OPTION_NAME></code> must be one of
501 the options listed above in upper case and segmented with underscores.
502 The <code>SNTP</code> variable will be tokenized and parsed like
503 the command line. The remaining variables are tested for existence and their
504 values are treated like option arguments.
505
506 <p class="noindent"><code>libopts</code> will search in 2 places for configuration files:
507 <ul>
508 <li>$HOME
509 <li>$PWD
510 </ul>
511 The environment variables <code>HOME</code>, and <code>PWD</code>
512 are expanded and replaced when <span class="file">sntp</span> runs.
513 For any of these that are plain files, they are simply processed.
514 For any that are directories, then a file named <span class="file">.ntprc</span> is searched for
515 within that directory and processed.
516
517 <p>Configuration files may be in a wide variety of formats.
518 The basic format is an option name followed by a value (argument) on the
519 same line. Values may be separated from the option name with a colon,
520 equal sign or simply white space. Values may be continued across multiple
521 lines by escaping the newline with a backslash.
522
523 <p>Multiple programs may also share the same initialization file.
524 Common options are collected at the top, followed by program specific
525 segments. The segments are separated by lines like:
526 <pre class="example"> [SNTP]
527 </pre>
528 <p class="noindent">or by
529 <pre class="example"> <?program sntp>
530 </pre>
531 <p class="noindent">Do not mix these styles within one configuration file.
532
533 <p>Compound values and carefully constructed string values may also be
534 specified using XML syntax:
535 <pre class="example"> <option-name>
536 <sub-opt>...&lt;...&gt;...</sub-opt>
537 </option-name>
538 </pre>
539 <p class="noindent">yielding an <code>option-name.sub-opt</code> string value of
540 <pre class="example"> "...<...>..."
541 </pre>
542 <p><code>AutoOpts</code> does not track suboptions. You simply note that it is a
543 hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching
544 the associated name/value pair list (see: optionFindValue).
545
546 <p>The command line options relating to configuration and/or usage help are:
547
548 <h5 class="subsubheading">version (-)</h5>
549
550 <p>Print the program version to standard out, optionally with licensing
551 information, then exit 0. The optional argument specifies how much licensing
552 detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument.
553 Only the first letter of the argument is examined:
554
555 <dl>
556 <dt><span class="samp">version</span><dd>Only print the version. This is the default.
557 <br><dt><span class="samp">copyright</span><dd>Name the copyright usage licensing terms.
558 <br><dt><span class="samp">verbose</span><dd>Print the full copyright usage licensing terms.
559 </dl>
560
561 <div class="node">
562 <p><hr>
563 <a name="sntp-exit-status"></a>Next: <a rel="next" accesskey="n" href="#sntp-Usage">sntp Usage</a>,
564 Previous: <a rel="previous" accesskey="p" href="#sntp-config">sntp config</a>,
565 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
566 <br>
567 </div>
568
569 <h4 class="subsection">sntp exit status</h4>
570
571 <p>One of the following exit values will be returned:
572 <dl>
573 <dt><span class="samp">0 (EXIT_SUCCESS)</span><dd>Successful program execution.
574 <br><dt><span class="samp">1 (EXIT_FAILURE)</span><dd>The operation failed or the command syntax was not valid.
575 <br><dt><span class="samp">66 (EX_NOINPUT)</span><dd>A specified configuration file could not be loaded.
576 <br><dt><span class="samp">70 (EX_SOFTWARE)</span><dd>libopts had an internal operational error. Please report
577 it to autogen-users (a] lists.sourceforge.net. Thank you.
578 </dl>
579 <div class="node">
580 <p><hr>
581 <a name="sntp-Usage"></a>Next: <a rel="next" accesskey="n" href="#sntp-Authors">sntp Authors</a>,
582 Previous: <a rel="previous" accesskey="p" href="#sntp-exit-status">sntp exit status</a>,
583 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
584 <br>
585 </div>
586
587 <h4 class="subsection">sntp Usage</h4>
588
589 <div class="node">
590 <p><hr>
591 <a name="sntp-Authors"></a>Previous: <a rel="previous" accesskey="p" href="#sntp-Usage">sntp Usage</a>,
592 Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
593 <br>
594 </div>
595
596 <h4 class="subsection">sntp Authors</h4>
597
598 <div class="node">
599 <p><hr>
600 <a name="Usage"></a>
601 <br>
602 </div>
603
604 <!-- node-name, next, previous, up -->
605 <h3 class="section">Usage</h3>
606
607 <p>The simplest use of this program is as an unprivileged command to
608 check the current time, offset, and error in the local clock.
609 For example:
610
611 <pre class="example"> sntp ntpserver.somewhere
612 </pre>
613 <p>With suitable privilege, it can be run as a command or in a
614 <code>crom</code> job to reset the local clock from a reliable server, like
615 the <code>ntpdate</code> and <code>rdate</code> commands.
616 For example:
617
618 <pre class="example"> sntp -a ntpserver.somewhere
619 </pre>
620 </body></html>
621
622