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22 1.1 kardel <h1 class="settitle">Sntp User's Manual</h1>
23 1.1 kardel <div class="node">
24 1.1 kardel <p><hr>
25 1.1.1.2 kardel <a name="Top"></a>Next: <a rel="next" accesskey="n" href="#sntp-Description">sntp Description</a>,
26 1.1 kardel Previous: <a rel="previous" accesskey="p" href="#dir">(dir)</a>,
27 1.1 kardel Up: <a rel="up" accesskey="u" href="#dir">(dir)</a>
28 1.1.1.2 kardel <br>
29 1.1 kardel </div>
30 1.1 kardel
31 1.1 kardel <h2 class="unnumbered">Simple Network Time Protocol User Manual</h2>
32 1.1 kardel
33 1.1 kardel <p>This document describes the use of the NTP Project's <code>sntp</code> program,
34 1.1 kardel that can be used to query a Network Time Protocol (NTP) server and
35 1.1 kardel display the time offset of the system clock relative to the server
36 1.1 kardel clock. Run as root, it can correct the system clock to this offset as
37 1.1 kardel well. It can be run as an interactive command or from a cron job.
38 1.1 kardel
39 1.1.1.5 christos <p>This document applies to version 4.2.8p2 of <code>sntp</code>.
40 1.1 kardel
41 1.1.1.2 kardel <p>The program implements the SNTP protocol as defined by RFC 5905, the NTPv4
42 1.1 kardel IETF specification.
43 1.1 kardel
44 1.1 kardel <div class="shortcontents">
45 1.1 kardel <h2>Short Contents</h2>
46 1.1 kardel <ul>
47 1.1 kardel <a href="#Top">Simple Network Time Protocol User Manual</a>
48 1.1 kardel </ul>
49 1.1 kardel </div>
50 1.1 kardel
51 1.1 kardel <ul class="menu">
52 1.1 kardel <li><a accesskey="1" href="#sntp-Description">sntp Description</a>: Description
53 1.1.1.2 kardel <li><a accesskey="2" href="#sntp-Invocation">sntp Invocation</a>: Invoking sntp
54 1.1.1.2 kardel <li><a accesskey="3" href="#Usage">Usage</a>: Usage
55 1.1 kardel </ul>
56 1.1 kardel
57 1.1 kardel <div class="node">
58 1.1 kardel <p><hr>
59 1.1.1.2 kardel <a name="sntp-Description"></a>
60 1.1.1.2 kardel <br>
61 1.1 kardel </div>
62 1.1 kardel
63 1.1 kardel <!-- node-name, next, previous, up -->
64 1.1 kardel <h3 class="section">Description</h3>
65 1.1 kardel
66 1.1 kardel <p>By default, <code>sntp</code> writes the local data and time (i.e., not UTC) to the
67 1.1 kardel standard output in the format:
68 1.1 kardel
69 1.1.1.3 christos <pre class="example"> 1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
70 1.1 kardel </pre>
71 1.1.1.3 christos <p>where
72 1.1.1.3 christos YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time,
73 1.1.1.3 christos (+0800) is the local timezone adjustment (so we would add 8 hours and 0 minutes to convert the reported local time to UTC),
74 1.1.1.3 christos and
75 1.1.1.3 christos the +4.567 +/- 0.089 secs indicates the time offset and
76 1.1 kardel error bound of the system clock relative to the server clock.
77 1.1 kardel
78 1.1 kardel <div class="node">
79 1.1 kardel <p><hr>
80 1.1.1.2 kardel <a name="sntp-Invocation"></a>
81 1.1.1.2 kardel <br>
82 1.1.1.2 kardel </div>
83 1.1.1.2 kardel
84 1.1.1.2 kardel <h3 class="section">Invoking sntp</h3>
85 1.1.1.2 kardel
86 1.1.1.3 christos <p><a name="index-sntp-1"></a><a name="index-standard-Simple-Network-Time-Protocol-client-program-2"></a>
87 1.1.1.3 christos
88 1.1.1.3 christos <p><code>sntp</code>
89 1.1.1.3 christos can be used as an SNTP client to query a NTP or SNTP server and either display
90 1.1.1.2 kardel the time or set the local system's time (given suitable privilege). It can be
91 1.1.1.3 christos run as an interactive command or from a
92 1.1.1.2 kardel <code>cron</code>
93 1.1.1.2 kardel job.
94 1.1.1.2 kardel
95 1.1.1.2 kardel <p>NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol)
96 1.1.1.2 kardel are defined and described by RFC 5905.
97 1.1.1.2 kardel
98 1.1.1.3 christos <p>The default is to write the estimated correct local date and time (i.e. not
99 1.1.1.3 christos UTC) to the standard output in a format like:
100 1.1.1.3 christos
101 1.1.1.3 christos <p><code>'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN'</code>
102 1.1.1.3 christos
103 1.1.1.2 kardel <p>where the
104 1.1.1.3 christos <code>'(+0800)'</code>
105 1.1.1.3 christos means that to get to UTC from the reported local time one must
106 1.1.1.3 christos add 8 hours and 0 minutes,
107 1.1.1.3 christos the
108 1.1.1.3 christos <code>'+4.567'</code>
109 1.1.1.3 christos indicates the local clock is 4.567 seconds behind the correct time
110 1.1.1.3 christos (so 4.567 seconds must be added to the local clock to get it to be correct).
111 1.1.1.3 christos Note that the number of decimals printed for this value will change
112 1.1.1.3 christos based on the reported precision of the server.
113 1.1.1.3 christos <code>'+/- 0.089'</code>
114 1.1.1.3 christos is the reported
115 1.1.1.3 christos <em>synchronization</em> <em>distance</em>
116 1.1.1.3 christos (in seconds), which represents the maximum error due to all causes.
117 1.1.1.3 christos If the server does not report valid data needed to calculate the
118 1.1.1.3 christos synchronization distance, this will be reported as
119 1.1.1.3 christos <code>'+/- ?'</code>.
120 1.1.1.3 christos If the
121 1.1.1.3 christos <em>host</em>
122 1.1.1.3 christos is different from the
123 1.1.1.3 christos <em>IP</em>,
124 1.1.1.3 christos both will be displayed.
125 1.1.1.3 christos Otherwise, only the
126 1.1.1.3 christos <em>IP</em>
127 1.1.1.3 christos is displayed.
128 1.1.1.3 christos Finally, the
129 1.1.1.3 christos <em>stratum</em>
130 1.1.1.5 christos of the host is reported
131 1.1.1.5 christos and the leap indicator is decoded and displayed.
132 1.1.1.2 kardel
133 1.1.1.2 kardel <p>This section was generated by <strong>AutoGen</strong>,
134 1.1.1.3 christos using the <code>agtexi-cmd</code> template and the option descriptions for the <code>sntp</code> program.
135 1.1.1.3 christos This software is released under the NTP license, <http://ntp.org/license>.
136 1.1.1.2 kardel
137 1.1.1.2 kardel <ul class="menu">
138 1.1.1.3 christos <li><a accesskey="1" href="#sntp-usage">sntp usage</a>: sntp help/usage (<span class="option">--help</span>)
139 1.1.1.3 christos <li><a accesskey="2" href="#sntp-ipv4">sntp ipv4</a>: ipv4 option (-4)
140 1.1.1.3 christos <li><a accesskey="3" href="#sntp-ipv6">sntp ipv6</a>: ipv6 option (-6)
141 1.1.1.3 christos <li><a accesskey="4" href="#sntp-authentication">sntp authentication</a>: authentication option (-a)
142 1.1.1.3 christos <li><a accesskey="5" href="#sntp-broadcast">sntp broadcast</a>: broadcast option (-b)
143 1.1.1.3 christos <li><a accesskey="6" href="#sntp-concurrent">sntp concurrent</a>: concurrent option (-c)
144 1.1.1.3 christos <li><a accesskey="7" href="#sntp-gap">sntp gap</a>: gap option (-g)
145 1.1.1.3 christos <li><a accesskey="8" href="#sntp-kod">sntp kod</a>: kod option (-K)
146 1.1.1.3 christos <li><a accesskey="9" href="#sntp-keyfile">sntp keyfile</a>: keyfile option (-k)
147 1.1.1.3 christos <li><a href="#sntp-logfile">sntp logfile</a>: logfile option (-l)
148 1.1.1.3 christos <li><a href="#sntp-steplimit">sntp steplimit</a>: steplimit option (-M)
149 1.1.1.3 christos <li><a href="#sntp-ntpversion">sntp ntpversion</a>: ntpversion option (-o)
150 1.1.1.3 christos <li><a href="#sntp-usereservedport">sntp usereservedport</a>: usereservedport option (-r)
151 1.1.1.3 christos <li><a href="#sntp-timeout">sntp timeout</a>: timeout option (-t)
152 1.1.1.3 christos <li><a href="#sntp-wait">sntp wait</a>: wait option
153 1.1.1.3 christos <li><a href="#sntp-config">sntp config</a>: presetting/configuring sntp
154 1.1.1.3 christos <li><a href="#sntp-exit-status">sntp exit status</a>: exit status
155 1.1.1.3 christos <li><a href="#sntp-Usage">sntp Usage</a>: Usage
156 1.1.1.3 christos <li><a href="#sntp-Authors">sntp Authors</a>: Authors
157 1.1.1.2 kardel </ul>
158 1.1.1.2 kardel
159 1.1.1.2 kardel <div class="node">
160 1.1.1.2 kardel <p><hr>
161 1.1.1.3 christos <a name="sntp-usage"></a>Next: <a rel="next" accesskey="n" href="#sntp-ipv4">sntp ipv4</a>,
162 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
163 1.1.1.2 kardel <br>
164 1.1.1.2 kardel </div>
165 1.1.1.2 kardel
166 1.1.1.3 christos <h4 class="subsection">sntp help/usage (<span class="option">--help</span>)</h4>
167 1.1.1.2 kardel
168 1.1.1.3 christos <p><a name="index-sntp-help-3"></a>
169 1.1.1.3 christos This is the automatically generated usage text for sntp.
170 1.1.1.2 kardel
171 1.1.1.3 christos <p>The text printed is the same whether selected with the <code>help</code> option
172 1.1.1.3 christos (<span class="option">--help</span>) or the <code>more-help</code> option (<span class="option">--more-help</span>). <code>more-help</code> will print
173 1.1.1.3 christos the usage text by passing it through a pager program.
174 1.1.1.3 christos <code>more-help</code> is disabled on platforms without a working
175 1.1.1.3 christos <code>fork(2)</code> function. The <code>PAGER</code> environment variable is
176 1.1.1.3 christos used to select the program, defaulting to <span class="file">more</span>. Both will exit
177 1.1.1.3 christos with a status code of 0.
178 1.1.1.3 christos
179 1.1.1.5 christos <pre class="example">sntp - standard Simple Network Time Protocol client program - Ver. 4.2.8p2
180 1.1.1.3 christos Usage: sntp [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \
181 1.1.1.2 kardel [ hostname-or-IP ...]
182 1.1.1.2 kardel Flg Arg Option-Name Description
183 1.1.1.2 kardel -4 no ipv4 Force IPv4 DNS name resolution
184 1.1.1.3 christos - prohibits the option 'ipv6'
185 1.1.1.2 kardel -6 no ipv6 Force IPv6 DNS name resolution
186 1.1.1.3 christos - prohibits the option 'ipv4'
187 1.1.1.2 kardel -a Num authentication Enable authentication with the key auth-keynumber
188 1.1.1.3 christos -b Str broadcast Listen to the address specified for broadcast time sync
189 1.1.1.3 christos - may appear multiple times
190 1.1.1.3 christos -c Str concurrent Concurrently query all IPs returned for host-name
191 1.1.1.3 christos - may appear multiple times
192 1.1.1.3 christos -d no debug-level Increase debug verbosity level
193 1.1.1.3 christos - may appear multiple times
194 1.1.1.3 christos -D Num set-debug-level Set the debug verbosity level
195 1.1.1.3 christos - may appear multiple times
196 1.1.1.3 christos -g Num gap The gap (in milliseconds) between time requests
197 1.1.1.3 christos -K Fil kod KoD history filename
198 1.1.1.3 christos -k Fil keyfile Look in this file for the key specified with -a
199 1.1.1.3 christos -l Fil logfile Log to specified logfile
200 1.1.1.3 christos -M Num steplimit Adjustments less than steplimit msec will be slewed
201 1.1.1.3 christos - it must be in the range:
202 1.1.1.3 christos greater than or equal to 0
203 1.1.1.3 christos -o Num ntpversion Send int as our NTP protocol version
204 1.1.1.3 christos - it must be in the range:
205 1.1.1.3 christos 0 to 7
206 1.1.1.3 christos -r no usereservedport Use the NTP Reserved Port (port 123)
207 1.1.1.3 christos -S no step OK to 'step' the time with settimeofday(2)
208 1.1.1.3 christos -s no slew OK to 'slew' the time with adjtime(2)
209 1.1.1.3 christos -t Num timeout The number of seconds to wait for responses
210 1.1.1.3 christos no wait Wait for pending replies (if not setting the time)
211 1.1.1.3 christos - disabled as '--no-wait'
212 1.1.1.3 christos - enabled by default
213 1.1.1.3 christos opt version output version information and exit
214 1.1.1.3 christos -? no help display extended usage information and exit
215 1.1.1.3 christos -! no more-help extended usage information passed thru pager
216 1.1.1.3 christos -> opt save-opts save the option state to a config file
217 1.1.1.3 christos -< Str load-opts load options from a config file
218 1.1.1.3 christos - disabled as '--no-load-opts'
219 1.1.1.2 kardel - may appear multiple times
220 1.1.1.2 kardel
221 1.1.1.2 kardel Options are specified by doubled hyphens and their name or by a single
222 1.1.1.2 kardel hyphen and the flag character.
223 1.1.1.2 kardel
224 1.1.1.2 kardel
225 1.1.1.2 kardel The following option preset mechanisms are supported:
226 1.1.1.2 kardel - reading file $HOME/.ntprc
227 1.1.1.2 kardel - reading file ./.ntprc
228 1.1.1.2 kardel - examining environment variables named SNTP_*
229 1.1.1.2 kardel
230 1.1.1.3 christos Please send bug reports to: <http://bugs.ntp.org, bugs (a] ntp.org>
231 1.1.1.2 kardel </pre>
232 1.1.1.2 kardel <div class="node">
233 1.1.1.2 kardel <p><hr>
234 1.1.1.3 christos <a name="sntp-ipv4"></a>Next: <a rel="next" accesskey="n" href="#sntp-ipv6">sntp ipv6</a>,
235 1.1.1.2 kardel Previous: <a rel="previous" accesskey="p" href="#sntp-usage">sntp usage</a>,
236 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
237 1.1.1.2 kardel <br>
238 1.1.1.2 kardel </div>
239 1.1.1.2 kardel
240 1.1.1.3 christos <h4 class="subsection">ipv4 option (-4)</h4>
241 1.1.1.2 kardel
242 1.1.1.3 christos <p><a name="index-sntp_002dipv4-4"></a>
243 1.1.1.3 christos This is the “force ipv4 dns name resolution” option.
244 1.1.1.2 kardel
245 1.1.1.3 christos <p class="noindent">This option has some usage constraints. It:
246 1.1.1.2 kardel <ul>
247 1.1.1.2 kardel <li>must not appear in combination with any of the following options:
248 1.1.1.3 christos ipv6.
249 1.1.1.2 kardel </ul>
250 1.1.1.2 kardel
251 1.1.1.3 christos <p>Force DNS resolution of the following host names on the command line
252 1.1.1.3 christos to the IPv4 namespace.
253 1.1.1.2 kardel <div class="node">
254 1.1.1.2 kardel <p><hr>
255 1.1.1.3 christos <a name="sntp-ipv6"></a>Next: <a rel="next" accesskey="n" href="#sntp-authentication">sntp authentication</a>,
256 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-ipv4">sntp ipv4</a>,
257 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
258 1.1.1.2 kardel <br>
259 1.1.1.2 kardel </div>
260 1.1.1.2 kardel
261 1.1.1.3 christos <h4 class="subsection">ipv6 option (-6)</h4>
262 1.1.1.3 christos
263 1.1.1.3 christos <p><a name="index-sntp_002dipv6-5"></a>
264 1.1.1.3 christos This is the “force ipv6 dns name resolution” option.
265 1.1.1.2 kardel
266 1.1.1.3 christos <p class="noindent">This option has some usage constraints. It:
267 1.1.1.3 christos <ul>
268 1.1.1.3 christos <li>must not appear in combination with any of the following options:
269 1.1.1.3 christos ipv4.
270 1.1.1.3 christos </ul>
271 1.1.1.2 kardel
272 1.1.1.3 christos <p>Force DNS resolution of the following host names on the command line
273 1.1.1.3 christos to the IPv6 namespace.
274 1.1.1.2 kardel <div class="node">
275 1.1.1.2 kardel <p><hr>
276 1.1.1.3 christos <a name="sntp-authentication"></a>Next: <a rel="next" accesskey="n" href="#sntp-broadcast">sntp broadcast</a>,
277 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-ipv6">sntp ipv6</a>,
278 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
279 1.1.1.2 kardel <br>
280 1.1.1.2 kardel </div>
281 1.1.1.2 kardel
282 1.1.1.3 christos <h4 class="subsection">authentication option (-a)</h4>
283 1.1.1.2 kardel
284 1.1.1.3 christos <p><a name="index-sntp_002dauthentication-6"></a>
285 1.1.1.3 christos This is the “enable authentication with the key <var>auth-keynumber</var>” option.
286 1.1.1.3 christos This option takes a number argument <span class="file">auth-keynumber</span>.
287 1.1.1.3 christos Enable authentication using the key specified in this option's
288 1.1.1.3 christos argument. The argument of this option is the <span class="option">keyid</span>, a
289 1.1.1.3 christos number specified in the <span class="option">keyfile</span> as this key's identifier.
290 1.1.1.3 christos See the <span class="option">keyfile</span> option (<span class="option">-k</span>) for more details.
291 1.1.1.2 kardel <div class="node">
292 1.1.1.2 kardel <p><hr>
293 1.1.1.3 christos <a name="sntp-broadcast"></a>Next: <a rel="next" accesskey="n" href="#sntp-concurrent">sntp concurrent</a>,
294 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-authentication">sntp authentication</a>,
295 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
296 1.1.1.2 kardel <br>
297 1.1.1.2 kardel </div>
298 1.1.1.2 kardel
299 1.1.1.3 christos <h4 class="subsection">broadcast option (-b)</h4>
300 1.1.1.2 kardel
301 1.1.1.3 christos <p><a name="index-sntp_002dbroadcast-7"></a>
302 1.1.1.3 christos This is the “listen to the address specified for broadcast time sync” option.
303 1.1.1.3 christos This option takes a string argument <span class="file">broadcast-address</span>.
304 1.1.1.2 kardel
305 1.1.1.3 christos <p class="noindent">This option has some usage constraints. It:
306 1.1.1.2 kardel <ul>
307 1.1.1.3 christos <li>may appear an unlimited number of times.
308 1.1.1.2 kardel </ul>
309 1.1.1.2 kardel
310 1.1.1.3 christos <p>If specified <code>sntp</code> will listen to the specified address
311 1.1.1.3 christos for NTP broadcasts. The default maximum wait time
312 1.1.1.3 christos can (and probably should) be modified with <span class="option">-t</span>.
313 1.1.1.2 kardel <div class="node">
314 1.1.1.2 kardel <p><hr>
315 1.1.1.3 christos <a name="sntp-concurrent"></a>Next: <a rel="next" accesskey="n" href="#sntp-gap">sntp gap</a>,
316 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-broadcast">sntp broadcast</a>,
317 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
318 1.1.1.2 kardel <br>
319 1.1.1.2 kardel </div>
320 1.1 kardel
321 1.1.1.3 christos <h4 class="subsection">concurrent option (-c)</h4>
322 1.1.1.2 kardel
323 1.1.1.3 christos <p><a name="index-sntp_002dconcurrent-8"></a>
324 1.1.1.3 christos This is the “concurrently query all ips returned for host-name” option.
325 1.1.1.3 christos This option takes a string argument <span class="file">host-name</span>.
326 1.1.1.2 kardel
327 1.1.1.3 christos <p class="noindent">This option has some usage constraints. It:
328 1.1.1.2 kardel <ul>
329 1.1.1.3 christos <li>may appear an unlimited number of times.
330 1.1.1.2 kardel </ul>
331 1.1.1.2 kardel
332 1.1.1.3 christos <p>Requests from an NTP "client" to a "server" should never be sent
333 1.1.1.3 christos more rapidly than one every 2 seconds. By default, any IPs returned
334 1.1.1.3 christos as part of a DNS lookup are assumed to be for a single instance of
335 1.1.1.3 christos <code>ntpd</code>, and therefore <code>sntp</code> will send queries to these IPs
336 1.1.1.3 christos one after another, with a 2-second gap in between each query.
337 1.1.1.2 kardel
338 1.1.1.3 christos <p>The <span class="option">-c</span> or <span class="option">--concurrent</span> flag says that any IPs
339 1.1.1.3 christos returned for the DNS lookup of the supplied host-name are on
340 1.1.1.3 christos different machines, so we can send concurrent queries.
341 1.1.1.2 kardel <div class="node">
342 1.1.1.2 kardel <p><hr>
343 1.1.1.3 christos <a name="sntp-gap"></a>Next: <a rel="next" accesskey="n" href="#sntp-kod">sntp kod</a>,
344 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-concurrent">sntp concurrent</a>,
345 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
346 1.1.1.2 kardel <br>
347 1.1.1.2 kardel </div>
348 1.1.1.2 kardel
349 1.1.1.3 christos <h4 class="subsection">gap option (-g)</h4>
350 1.1.1.2 kardel
351 1.1.1.3 christos <p><a name="index-sntp_002dgap-9"></a>
352 1.1.1.3 christos This is the “the gap (in milliseconds) between time requests” option.
353 1.1.1.3 christos This option takes a number argument <span class="file">milliseconds</span>.
354 1.1.1.3 christos Since we're only going to use the first valid response we get and
355 1.1.1.3 christos there is benefit to specifying a good number of servers to query,
356 1.1.1.3 christos separate the queries we send out by the specified number of
357 1.1.1.3 christos milliseconds.
358 1.1.1.2 kardel <div class="node">
359 1.1.1.2 kardel <p><hr>
360 1.1.1.3 christos <a name="sntp-kod"></a>Next: <a rel="next" accesskey="n" href="#sntp-keyfile">sntp keyfile</a>,
361 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-gap">sntp gap</a>,
362 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
363 1.1.1.2 kardel <br>
364 1.1.1.2 kardel </div>
365 1.1.1.2 kardel
366 1.1.1.2 kardel <h4 class="subsection">kod option (-K)</h4>
367 1.1.1.2 kardel
368 1.1.1.2 kardel <p><a name="index-sntp_002dkod-10"></a>
369 1.1.1.2 kardel This is the “kod history filename” option.
370 1.1.1.3 christos This option takes a file argument <span class="file">file-name</span>.
371 1.1.1.3 christos Specifies the filename to be used for the persistent history of KoD
372 1.1.1.4 christos responses received from servers. If the file does not exist, a
373 1.1.1.4 christos warning message will be displayed. The file will not be created.
374 1.1.1.2 kardel <div class="node">
375 1.1.1.2 kardel <p><hr>
376 1.1.1.3 christos <a name="sntp-keyfile"></a>Next: <a rel="next" accesskey="n" href="#sntp-logfile">sntp logfile</a>,
377 1.1.1.2 kardel Previous: <a rel="previous" accesskey="p" href="#sntp-kod">sntp kod</a>,
378 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
379 1.1.1.2 kardel <br>
380 1.1.1.2 kardel </div>
381 1.1.1.2 kardel
382 1.1.1.3 christos <h4 class="subsection">keyfile option (-k)</h4>
383 1.1.1.3 christos
384 1.1.1.3 christos <p><a name="index-sntp_002dkeyfile-11"></a>
385 1.1.1.3 christos This is the “look in this file for the key specified with <span class="option">-a</span>” option.
386 1.1.1.3 christos This option takes a file argument <span class="file">file-name</span>.
387 1.1.1.3 christos This option specifies the keyfile.
388 1.1.1.3 christos <code>sntp</code> will search for the key specified with <span class="option">-a</span>
389 1.1.1.3 christos <span class="file">keyno</span> in this file. See <span class="command">ntp.keys(5)</span> for more
390 1.1.1.3 christos information.
391 1.1.1.3 christos <div class="node">
392 1.1.1.3 christos <p><hr>
393 1.1.1.3 christos <a name="sntp-logfile"></a>Next: <a rel="next" accesskey="n" href="#sntp-steplimit">sntp steplimit</a>,
394 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-keyfile">sntp keyfile</a>,
395 1.1.1.3 christos Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
396 1.1.1.3 christos <br>
397 1.1.1.3 christos </div>
398 1.1.1.3 christos
399 1.1.1.2 kardel <h4 class="subsection">logfile option (-l)</h4>
400 1.1.1.2 kardel
401 1.1.1.3 christos <p><a name="index-sntp_002dlogfile-12"></a>
402 1.1.1.3 christos This is the “log to specified logfile” option.
403 1.1.1.3 christos This option takes a file argument <span class="file">file-name</span>.
404 1.1.1.3 christos This option causes the client to write log messages to the specified
405 1.1.1.3 christos <span class="file">logfile</span>.
406 1.1.1.3 christos <div class="node">
407 1.1.1.3 christos <p><hr>
408 1.1.1.3 christos <a name="sntp-steplimit"></a>Next: <a rel="next" accesskey="n" href="#sntp-ntpversion">sntp ntpversion</a>,
409 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-logfile">sntp logfile</a>,
410 1.1.1.3 christos Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
411 1.1.1.3 christos <br>
412 1.1.1.3 christos </div>
413 1.1.1.2 kardel
414 1.1.1.3 christos <h4 class="subsection">steplimit option (-M)</h4>
415 1.1.1.3 christos
416 1.1.1.3 christos <p><a name="index-sntp_002dsteplimit-13"></a>
417 1.1.1.3 christos This is the “adjustments less than <var>steplimit</var> msec will be slewed” option.
418 1.1.1.3 christos This option takes a number argument.
419 1.1.1.3 christos If the time adjustment is less than <span class="file">steplimit</span> milliseconds,
420 1.1.1.3 christos slew the amount using <span class="command">adjtime(2)</span>. Otherwise, step the
421 1.1.1.5 christos correction using <span class="command">settimeofday(2)</span>. The default value is 0,
422 1.1.1.5 christos which means all adjustments will be stepped. This is a feature, as
423 1.1.1.5 christos different situations demand different values.
424 1.1.1.3 christos <div class="node">
425 1.1.1.3 christos <p><hr>
426 1.1.1.3 christos <a name="sntp-ntpversion"></a>Next: <a rel="next" accesskey="n" href="#sntp-usereservedport">sntp usereservedport</a>,
427 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-steplimit">sntp steplimit</a>,
428 1.1.1.3 christos Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
429 1.1.1.3 christos <br>
430 1.1.1.3 christos </div>
431 1.1.1.2 kardel
432 1.1.1.3 christos <h4 class="subsection">ntpversion option (-o)</h4>
433 1.1.1.2 kardel
434 1.1.1.3 christos <p><a name="index-sntp_002dntpversion-14"></a>
435 1.1.1.3 christos This is the “send <var>int</var> as our ntp protocol version” option.
436 1.1.1.3 christos This option takes a number argument.
437 1.1.1.3 christos When sending requests to a remote server, tell them we are running
438 1.1.1.3 christos NTP protocol version <span class="file">ntpversion</span> .
439 1.1.1.2 kardel <div class="node">
440 1.1.1.2 kardel <p><hr>
441 1.1.1.3 christos <a name="sntp-usereservedport"></a>Next: <a rel="next" accesskey="n" href="#sntp-timeout">sntp timeout</a>,
442 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-ntpversion">sntp ntpversion</a>,
443 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
444 1.1.1.2 kardel <br>
445 1.1.1.2 kardel </div>
446 1.1.1.2 kardel
447 1.1.1.3 christos <h4 class="subsection">usereservedport option (-r)</h4>
448 1.1.1.2 kardel
449 1.1.1.3 christos <p><a name="index-sntp_002dusereservedport-15"></a>
450 1.1.1.3 christos This is the “use the ntp reserved port (port 123)” option.
451 1.1.1.3 christos Use port 123, which is reserved for NTP, for our network
452 1.1.1.3 christos communications.
453 1.1.1.3 christos <div class="node">
454 1.1.1.3 christos <p><hr>
455 1.1.1.3 christos <a name="sntp-timeout"></a>Next: <a rel="next" accesskey="n" href="#sntp-wait">sntp wait</a>,
456 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-usereservedport">sntp usereservedport</a>,
457 1.1.1.3 christos Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
458 1.1.1.3 christos <br>
459 1.1.1.3 christos </div>
460 1.1.1.3 christos
461 1.1.1.3 christos <h4 class="subsection">timeout option (-t)</h4>
462 1.1.1.2 kardel
463 1.1.1.3 christos <p><a name="index-sntp_002dtimeout-16"></a>
464 1.1.1.3 christos This is the “the number of seconds to wait for responses” option.
465 1.1.1.3 christos This option takes a number argument <span class="file">seconds</span>.
466 1.1.1.3 christos When waiting for a reply, <code>sntp</code> will wait the number
467 1.1.1.3 christos of seconds specified before giving up. The default should be
468 1.1.1.3 christos more than enough for a unicast response. If <code>sntp</code> is
469 1.1.1.3 christos only waiting for a broadcast response a longer timeout is
470 1.1.1.3 christos likely needed.
471 1.1.1.2 kardel <div class="node">
472 1.1.1.2 kardel <p><hr>
473 1.1.1.3 christos <a name="sntp-wait"></a>Next: <a rel="next" accesskey="n" href="#sntp-config">sntp config</a>,
474 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-timeout">sntp timeout</a>,
475 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
476 1.1.1.2 kardel <br>
477 1.1.1.2 kardel </div>
478 1.1.1.2 kardel
479 1.1.1.3 christos <h4 class="subsection">wait option</h4>
480 1.1.1.2 kardel
481 1.1.1.3 christos <p><a name="index-sntp_002dwait-17"></a>
482 1.1.1.3 christos This is the “wait for pending replies (if not setting the time)” option.
483 1.1.1.2 kardel
484 1.1.1.3 christos <p class="noindent">This option has some usage constraints. It:
485 1.1.1.2 kardel <ul>
486 1.1.1.3 christos <li>can be disabled with –no-wait.
487 1.1.1.3 christos <li>It is enabled by default.
488 1.1.1.2 kardel </ul>
489 1.1.1.2 kardel
490 1.1.1.3 christos <p>If we are not setting the time, wait for all pending responses.
491 1.1.1.3 christos
492 1.1.1.2 kardel <div class="node">
493 1.1.1.2 kardel <p><hr>
494 1.1.1.3 christos <a name="sntp-config"></a>Next: <a rel="next" accesskey="n" href="#sntp-exit-status">sntp exit status</a>,
495 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-wait">sntp wait</a>,
496 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
497 1.1.1.2 kardel <br>
498 1.1.1.2 kardel </div>
499 1.1.1.2 kardel
500 1.1.1.3 christos <h4 class="subsection">presetting/configuring sntp</h4>
501 1.1.1.2 kardel
502 1.1.1.3 christos <p>Any option that is not marked as <i>not presettable</i> may be preset by
503 1.1.1.3 christos 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
504 1.1.1.3 christos the options listed above in upper case and segmented with underscores.
505 1.1.1.3 christos The <code>SNTP</code> variable will be tokenized and parsed like
506 1.1.1.3 christos the command line. The remaining variables are tested for existence and their
507 1.1.1.3 christos values are treated like option arguments.
508 1.1.1.2 kardel
509 1.1.1.3 christos <p class="noindent"><code>libopts</code> will search in 2 places for configuration files:
510 1.1.1.2 kardel <ul>
511 1.1.1.3 christos <li>$HOME
512 1.1.1.3 christos <li>$PWD
513 1.1.1.2 kardel </ul>
514 1.1.1.3 christos The environment variables <code>HOME</code>, and <code>PWD</code>
515 1.1.1.3 christos are expanded and replaced when <span class="file">sntp</span> runs.
516 1.1.1.3 christos For any of these that are plain files, they are simply processed.
517 1.1.1.3 christos For any that are directories, then a file named <span class="file">.ntprc</span> is searched for
518 1.1.1.3 christos within that directory and processed.
519 1.1.1.3 christos
520 1.1.1.3 christos <p>Configuration files may be in a wide variety of formats.
521 1.1.1.3 christos The basic format is an option name followed by a value (argument) on the
522 1.1.1.3 christos same line. Values may be separated from the option name with a colon,
523 1.1.1.3 christos equal sign or simply white space. Values may be continued across multiple
524 1.1.1.3 christos lines by escaping the newline with a backslash.
525 1.1.1.3 christos
526 1.1.1.3 christos <p>Multiple programs may also share the same initialization file.
527 1.1.1.3 christos Common options are collected at the top, followed by program specific
528 1.1.1.3 christos segments. The segments are separated by lines like:
529 1.1.1.3 christos <pre class="example"> [SNTP]
530 1.1.1.3 christos </pre>
531 1.1.1.3 christos <p class="noindent">or by
532 1.1.1.3 christos <pre class="example"> <?program sntp>
533 1.1.1.3 christos </pre>
534 1.1.1.3 christos <p class="noindent">Do not mix these styles within one configuration file.
535 1.1.1.3 christos
536 1.1.1.3 christos <p>Compound values and carefully constructed string values may also be
537 1.1.1.3 christos specified using XML syntax:
538 1.1.1.3 christos <pre class="example"> <option-name>
539 1.1.1.3 christos <sub-opt>...&lt;...&gt;...</sub-opt>
540 1.1.1.3 christos </option-name>
541 1.1.1.3 christos </pre>
542 1.1.1.3 christos <p class="noindent">yielding an <code>option-name.sub-opt</code> string value of
543 1.1.1.3 christos <pre class="example"> "...<...>..."
544 1.1.1.3 christos </pre>
545 1.1.1.3 christos <p><code>AutoOpts</code> does not track suboptions. You simply note that it is a
546 1.1.1.3 christos hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching
547 1.1.1.3 christos the associated name/value pair list (see: optionFindValue).
548 1.1.1.3 christos
549 1.1.1.3 christos <p>The command line options relating to configuration and/or usage help are:
550 1.1.1.2 kardel
551 1.1.1.3 christos <h5 class="subsubheading">version (-)</h5>
552 1.1.1.3 christos
553 1.1.1.3 christos <p>Print the program version to standard out, optionally with licensing
554 1.1.1.3 christos information, then exit 0. The optional argument specifies how much licensing
555 1.1.1.3 christos detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument.
556 1.1.1.3 christos Only the first letter of the argument is examined:
557 1.1.1.3 christos
558 1.1.1.3 christos <dl>
559 1.1.1.3 christos <dt><span class="samp">version</span><dd>Only print the version. This is the default.
560 1.1.1.3 christos <br><dt><span class="samp">copyright</span><dd>Name the copyright usage licensing terms.
561 1.1.1.3 christos <br><dt><span class="samp">verbose</span><dd>Print the full copyright usage licensing terms.
562 1.1.1.3 christos </dl>
563 1.1.1.2 kardel
564 1.1.1.2 kardel <div class="node">
565 1.1.1.2 kardel <p><hr>
566 1.1.1.3 christos <a name="sntp-exit-status"></a>Next: <a rel="next" accesskey="n" href="#sntp-Usage">sntp Usage</a>,
567 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-config">sntp config</a>,
568 1.1.1.2 kardel Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
569 1.1.1.2 kardel <br>
570 1.1.1.2 kardel </div>
571 1.1.1.2 kardel
572 1.1.1.3 christos <h4 class="subsection">sntp exit status</h4>
573 1.1.1.3 christos
574 1.1.1.3 christos <p>One of the following exit values will be returned:
575 1.1.1.3 christos <dl>
576 1.1.1.3 christos <dt><span class="samp">0 (EXIT_SUCCESS)</span><dd>Successful program execution.
577 1.1.1.3 christos <br><dt><span class="samp">1 (EXIT_FAILURE)</span><dd>The operation failed or the command syntax was not valid.
578 1.1.1.3 christos <br><dt><span class="samp">66 (EX_NOINPUT)</span><dd>A specified configuration file could not be loaded.
579 1.1.1.3 christos <br><dt><span class="samp">70 (EX_SOFTWARE)</span><dd>libopts had an internal operational error. Please report
580 1.1.1.3 christos it to autogen-users (a] lists.sourceforge.net. Thank you.
581 1.1.1.3 christos </dl>
582 1.1.1.3 christos <div class="node">
583 1.1.1.3 christos <p><hr>
584 1.1.1.3 christos <a name="sntp-Usage"></a>Next: <a rel="next" accesskey="n" href="#sntp-Authors">sntp Authors</a>,
585 1.1.1.3 christos Previous: <a rel="previous" accesskey="p" href="#sntp-exit-status">sntp exit status</a>,
586 1.1.1.3 christos Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
587 1.1.1.3 christos <br>
588 1.1.1.3 christos </div>
589 1.1.1.3 christos
590 1.1.1.3 christos <h4 class="subsection">sntp Usage</h4>
591 1.1.1.3 christos
592 1.1.1.3 christos <div class="node">
593 1.1.1.3 christos <p><hr>
594 1.1.1.4 christos <a name="sntp-Authors"></a>Previous: <a rel="previous" accesskey="p" href="#sntp-Usage">sntp Usage</a>,
595 1.1.1.3 christos Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a>
596 1.1.1.3 christos <br>
597 1.1.1.3 christos </div>
598 1.1.1.3 christos
599 1.1.1.3 christos <h4 class="subsection">sntp Authors</h4>
600 1.1.1.3 christos
601 1.1.1.3 christos <div class="node">
602 1.1.1.3 christos <p><hr>
603 1.1.1.2 kardel <a name="Usage"></a>
604 1.1.1.2 kardel <br>
605 1.1 kardel </div>
606 1.1 kardel
607 1.1 kardel <!-- node-name, next, previous, up -->
608 1.1 kardel <h3 class="section">Usage</h3>
609 1.1 kardel
610 1.1 kardel <p>The simplest use of this program is as an unprivileged command to
611 1.1 kardel check the current time, offset, and error in the local clock.
612 1.1 kardel For example:
613 1.1 kardel
614 1.1.1.2 kardel <pre class="example"> sntp ntpserver.somewhere
615 1.1 kardel </pre>
616 1.1 kardel <p>With suitable privilege, it can be run as a command or in a
617 1.1 kardel <code>crom</code> job to reset the local clock from a reliable server, like
618 1.1 kardel the <code>ntpdate</code> and <code>rdate</code> commands.
619 1.1 kardel For example:
620 1.1 kardel
621 1.1.1.2 kardel <pre class="example"> sntp -a ntpserver.somewhere
622 1.1 kardel </pre>
623 1.1 kardel </body></html>
624 1.1 kardel
625