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38 1.1.1.15 christos <h1 class="settitle" align="center">Sntp User’s Manual</h1>
39 1.1.1.15 christos
40 1.1.1.15 christos
41 1.1.1.15 christos
42 1.1.1.15 christos
43 1.1 kardel
44 1.1.1.17 christos <span id="Top"></span><div class="header">
45 1.1.1.15 christos <p>
46 1.1.1.15 christos Next: <a href="#sntp-Description" accesskey="n" rel="next">sntp Description</a>, Previous: <a href="dir.html#Top" accesskey="p" rel="prev">(dir)</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> </p>
47 1.1.1.15 christos </div>
48 1.1.1.17 christos <span id="Simple-Network-Time-Protocol-User-Manual"></span><h1 class="top">Simple Network Time Protocol User Manual</h1>
49 1.1.1.15 christos
50 1.1.1.15 christos <p>This document describes the use of the NTP Project’s <code>sntp</code> program,
51 1.1 kardel that can be used to query a Network Time Protocol (NTP) server and
52 1.1 kardel display the time offset of the system clock relative to the server
53 1.1 kardel clock. Run as root, it can correct the system clock to this offset as
54 1.1 kardel well. It can be run as an interactive command or from a cron job.
55 1.1.1.15 christos </p>
56 1.1.1.17 christos <p>This document applies to version 4.2.8p18 of <code>sntp</code>.
57 1.1.1.15 christos </p>
58 1.1.1.15 christos <p>The program implements the SNTP protocol as defined by RFC 5905, the NTPv4
59 1.1 kardel IETF specification.
60 1.1.1.15 christos </p>
61 1.1.1.17 christos <span id="SEC_Overview"></span>
62 1.1.1.15 christos <h2 class="shortcontents-heading">Short Table of Contents</h2>
63 1.1.1.15 christos
64 1.1.1.15 christos <div class="shortcontents">
65 1.1.1.15 christos <ul class="no-bullet">
66 1.1.1.17 christos <li><a id="stoc-Description" href="#toc-Description">1 Description</a></li>
67 1.1 kardel </ul>
68 1.1 kardel </div>
69 1.1 kardel
70 1.1 kardel
71 1.1.1.15 christos <table class="menu" border="0" cellspacing="0">
72 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-Description" accesskey="1">sntp Description</a></td><td> </td><td align="left" valign="top">Description
73 1.1.1.15 christos </td></tr>
74 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-Invocation" accesskey="2">sntp Invocation</a></td><td> </td><td align="left" valign="top">Invoking sntp
75 1.1.1.15 christos </td></tr>
76 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#Usage" accesskey="3">Usage</a></td><td> </td><td align="left" valign="top">Usage
77 1.1.1.15 christos </td></tr>
78 1.1.1.15 christos </table>
79 1.1.1.15 christos
80 1.1.1.15 christos <hr>
81 1.1.1.17 christos <span id="sntp-Description"></span><div class="header">
82 1.1.1.15 christos <p>
83 1.1.1.15 christos Next: <a href="#sntp-Invocation" accesskey="n" rel="next">sntp Invocation</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p>
84 1.1 kardel </div>
85 1.1.1.17 christos <span id="Description"></span><h2 class="chapter">1 Description</h2>
86 1.1 kardel
87 1.1 kardel <p>By default, <code>sntp</code> writes the local data and time (i.e., not UTC) to the
88 1.1 kardel standard output in the format:
89 1.1.1.15 christos </p>
90 1.1.1.15 christos <div class="example">
91 1.1.1.15 christos <pre class="example">1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
92 1.1.1.15 christos </pre></div>
93 1.1 kardel
94 1.1.1.15 christos <p>where
95 1.1.1.3 christos YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time,
96 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),
97 1.1.1.3 christos and
98 1.1.1.3 christos the +4.567 +/- 0.089 secs indicates the time offset and
99 1.1 kardel error bound of the system clock relative to the server clock.
100 1.1.1.15 christos </p>
101 1.1.1.15 christos <table class="menu" border="0" cellspacing="0">
102 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-Invocation" accesskey="1">Invoking sntp</a></td><td> </td><td align="left" valign="top">
103 1.1.1.15 christos </td></tr>
104 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#Usage" accesskey="2">Usage</a></td><td> </td><td align="left" valign="top">
105 1.1.1.15 christos </td></tr>
106 1.1.1.15 christos </table>
107 1.1 kardel
108 1.1.1.15 christos <hr>
109 1.1.1.17 christos <span id="sntp-Invocation"></span><div class="header">
110 1.1.1.15 christos <p>
111 1.1.1.15 christos Next: <a href="#Usage" accesskey="n" rel="next">Usage</a>, Previous: <a href="#sntp-Description" accesskey="p" rel="prev">sntp Description</a>, Up: <a href="#sntp-Description" accesskey="u" rel="up">sntp Description</a> </p>
112 1.1.1.2 kardel </div>
113 1.1.1.17 christos <span id="Invoking-sntp"></span><h3 class="section">1.1 Invoking sntp</h3>
114 1.1.1.17 christos <span id="index-sntp"></span>
115 1.1.1.17 christos <span id="index-standard-Simple-Network-Time-Protocol-client-program"></span>
116 1.1.1.2 kardel
117 1.1.1.2 kardel
118 1.1.1.3 christos
119 1.1.1.15 christos <p><code>sntp</code>
120 1.1.1.3 christos can be used as an SNTP client to query a NTP or SNTP server and either display
121 1.1.1.15 christos the time or set the local system’s time (given suitable privilege). It can be
122 1.1.1.3 christos run as an interactive command or from a
123 1.1.1.2 kardel <code>cron</code>
124 1.1.1.2 kardel job.
125 1.1.1.15 christos </p>
126 1.1.1.15 christos <p>NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol)
127 1.1.1.2 kardel are defined and described by RFC 5905.
128 1.1.1.15 christos </p>
129 1.1.1.2 kardel
130 1.1.1.15 christos <p>The default is to write the estimated correct local date and time (i.e. not
131 1.1.1.3 christos UTC) to the standard output in a format like:
132 1.1.1.15 christos </p>
133 1.1.1.15 christos <p><code>'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN'</code>
134 1.1.1.15 christos </p>
135 1.1.1.15 christos <p>where the
136 1.1.1.3 christos <code>'(+0800)'</code>
137 1.1.1.3 christos means that to get to UTC from the reported local time one must
138 1.1.1.3 christos add 8 hours and 0 minutes,
139 1.1.1.3 christos the
140 1.1.1.3 christos <code>'+4.567'</code>
141 1.1.1.3 christos indicates the local clock is 4.567 seconds behind the correct time
142 1.1.1.15 christos (so 4.567 seconds must be added to the local clock to get it to be correct).
143 1.1.1.3 christos Note that the number of decimals printed for this value will change
144 1.1.1.15 christos based on the reported precision of the server.
145 1.1.1.3 christos <code>'+/- 0.089'</code>
146 1.1.1.3 christos is the reported
147 1.1.1.3 christos <em>synchronization</em> <em>distance</em>
148 1.1.1.15 christos (in seconds), which represents the maximum error due to all causes.
149 1.1.1.3 christos If the server does not report valid data needed to calculate the
150 1.1.1.3 christos synchronization distance, this will be reported as
151 1.1.1.15 christos <code>'+/- ?'</code>.
152 1.1.1.3 christos If the
153 1.1.1.3 christos <em>host</em>
154 1.1.1.3 christos is different from the
155 1.1.1.3 christos <em>IP</em>,
156 1.1.1.15 christos both will be displayed.
157 1.1.1.15 christos Otherwise, only the
158 1.1.1.3 christos <em>IP</em>
159 1.1.1.15 christos is displayed.
160 1.1.1.3 christos Finally, the
161 1.1.1.3 christos <em>stratum</em>
162 1.1.1.5 christos of the host is reported
163 1.1.1.5 christos and the leap indicator is decoded and displayed.
164 1.1.1.15 christos </p>
165 1.1.1.15 christos <p>This section was generated by <strong>AutoGen</strong>,
166 1.1.1.15 christos using the <code>agtexi-cmd</code> template and the option descriptions for the <code>sntp</code> program.
167 1.1.1.3 christos This software is released under the NTP license, <http://ntp.org/license>.
168 1.1.1.15 christos </p>
169 1.1.1.15 christos <table class="menu" border="0" cellspacing="0">
170 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-usage" accesskey="1">sntp usage</a></td><td> </td><td align="left" valign="top">sntp help/usage (<samp>--help</samp>)
171 1.1.1.15 christos </td></tr>
172 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-ipv4" accesskey="2">sntp ipv4</a></td><td> </td><td align="left" valign="top">ipv4 option (-4)
173 1.1.1.15 christos </td></tr>
174 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-ipv6" accesskey="3">sntp ipv6</a></td><td> </td><td align="left" valign="top">ipv6 option (-6)
175 1.1.1.15 christos </td></tr>
176 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-authentication" accesskey="4">sntp authentication</a></td><td> </td><td align="left" valign="top">authentication option (-a)
177 1.1.1.15 christos </td></tr>
178 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-broadcast" accesskey="5">sntp broadcast</a></td><td> </td><td align="left" valign="top">broadcast option (-b)
179 1.1.1.15 christos </td></tr>
180 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-concurrent" accesskey="6">sntp concurrent</a></td><td> </td><td align="left" valign="top">concurrent option (-c)
181 1.1.1.15 christos </td></tr>
182 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-gap" accesskey="7">sntp gap</a></td><td> </td><td align="left" valign="top">gap option (-g)
183 1.1.1.15 christos </td></tr>
184 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-kod" accesskey="8">sntp kod</a></td><td> </td><td align="left" valign="top">kod option (-K)
185 1.1.1.15 christos </td></tr>
186 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-keyfile" accesskey="9">sntp keyfile</a></td><td> </td><td align="left" valign="top">keyfile option (-k)
187 1.1.1.15 christos </td></tr>
188 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-logfile">sntp logfile</a></td><td> </td><td align="left" valign="top">logfile option (-l)
189 1.1.1.15 christos </td></tr>
190 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-steplimit">sntp steplimit</a></td><td> </td><td align="left" valign="top">steplimit option (-M)
191 1.1.1.15 christos </td></tr>
192 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-ntpversion">sntp ntpversion</a></td><td> </td><td align="left" valign="top">ntpversion option (-o)
193 1.1.1.15 christos </td></tr>
194 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-usereservedport">sntp usereservedport</a></td><td> </td><td align="left" valign="top">usereservedport option (-r)
195 1.1.1.15 christos </td></tr>
196 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-timeout">sntp timeout</a></td><td> </td><td align="left" valign="top">timeout option (-t)
197 1.1.1.15 christos </td></tr>
198 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-wait">sntp wait</a></td><td> </td><td align="left" valign="top">wait option
199 1.1.1.15 christos </td></tr>
200 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-config">sntp config</a></td><td> </td><td align="left" valign="top">presetting/configuring sntp
201 1.1.1.15 christos </td></tr>
202 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-exit-status">sntp exit status</a></td><td> </td><td align="left" valign="top">exit status
203 1.1.1.15 christos </td></tr>
204 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-Usage">sntp Usage</a></td><td> </td><td align="left" valign="top">Usage
205 1.1.1.15 christos </td></tr>
206 1.1.1.17 christos <tr><td align="left" valign="top">• <a href="#sntp-Authors">sntp Authors</a></td><td> </td><td align="left" valign="top">Authors
207 1.1.1.15 christos </td></tr>
208 1.1.1.15 christos </table>
209 1.1.1.15 christos
210 1.1.1.15 christos <hr>
211 1.1.1.17 christos <span id="sntp-usage"></span><div class="header">
212 1.1.1.15 christos <p>
213 1.1.1.15 christos Next: <a href="#sntp-ipv4" accesskey="n" rel="next">sntp ipv4</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
214 1.1.1.15 christos </div>
215 1.1.1.17 christos <span id="sntp-help_002fusage-_0028_002d_002dhelp_0029"></span><h4 class="subsection">1.1.1 sntp help/usage (<samp>--help</samp>)</h4>
216 1.1.1.17 christos <span id="index-sntp-help"></span>
217 1.1.1.15 christos
218 1.1.1.15 christos <p>This is the automatically generated usage text for sntp.
219 1.1.1.15 christos </p>
220 1.1.1.15 christos <p>The text printed is the same whether selected with the <code>help</code> option
221 1.1.1.15 christos (<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>). <code>more-help</code> will print
222 1.1.1.15 christos the usage text by passing it through a pager program.
223 1.1.1.3 christos <code>more-help</code> is disabled on platforms without a working
224 1.1.1.3 christos <code>fork(2)</code> function. The <code>PAGER</code> environment variable is
225 1.1.1.15 christos used to select the program, defaulting to <samp>more</samp>. Both will exit
226 1.1.1.3 christos with a status code of 0.
227 1.1.1.15 christos </p>
228 1.1.1.15 christos <div class="example">
229 1.1.1.17 christos <pre class="example">sntp - standard Simple Network Time Protocol client program - Ver. 4.2.8p18
230 1.1.1.14 christos Usage: sntp [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \
231 1.1.1.2 kardel [ hostname-or-IP ...]
232 1.1.1.2 kardel Flg Arg Option-Name Description
233 1.1.1.2 kardel -4 no ipv4 Force IPv4 DNS name resolution
234 1.1.1.14 christos - prohibits the option 'ipv6'
235 1.1.1.2 kardel -6 no ipv6 Force IPv6 DNS name resolution
236 1.1.1.14 christos - prohibits the option 'ipv4'
237 1.1.1.14 christos -a Num authentication Enable authentication with the key auth-keynumber
238 1.1.1.3 christos -b Str broadcast Listen to the address specified for broadcast time sync
239 1.1.1.3 christos - may appear multiple times
240 1.1.1.3 christos -c Str concurrent Concurrently query all IPs returned for host-name
241 1.1.1.3 christos - may appear multiple times
242 1.1.1.3 christos -d no debug-level Increase debug verbosity level
243 1.1.1.3 christos - may appear multiple times
244 1.1.1.14 christos -D Num set-debug-level Set the debug verbosity level
245 1.1.1.3 christos - may appear multiple times
246 1.1.1.3 christos -g Num gap The gap (in milliseconds) between time requests
247 1.1.1.3 christos -K Fil kod KoD history filename
248 1.1.1.14 christos -k Fil keyfile Look in this file for the key specified with -a
249 1.1.1.3 christos -l Fil logfile Log to specified logfile
250 1.1.1.14 christos -M Num steplimit Adjustments less than steplimit msec will be slewed
251 1.1.1.14 christos - it must be in the range:
252 1.1.1.3 christos greater than or equal to 0
253 1.1.1.14 christos -o Num ntpversion Send int as our NTP protocol version
254 1.1.1.14 christos - it must be in the range:
255 1.1.1.3 christos 0 to 7
256 1.1.1.3 christos -r no usereservedport Use the NTP Reserved Port (port 123)
257 1.1.1.14 christos -S no step OK to 'step' the time with settimeofday(2)
258 1.1.1.14 christos -s no slew OK to 'slew' the time with adjtime(2)
259 1.1.1.14 christos -t Num timeout The number of seconds to wait for responses
260 1.1.1.3 christos no wait Wait for pending replies (if not setting the time)
261 1.1.1.14 christos - disabled as '--no-wait'
262 1.1.1.3 christos - enabled by default
263 1.1.1.14 christos opt version output version information and exit
264 1.1.1.14 christos -? no help display extended usage information and exit
265 1.1.1.14 christos -! no more-help extended usage information passed thru pager
266 1.1.1.14 christos -> opt save-opts save the option state to a config file
267 1.1.1.14 christos -< Str load-opts load options from a config file
268 1.1.1.14 christos - disabled as '--no-load-opts'
269 1.1.1.2 kardel - may appear multiple times
270 1.1.1.2 kardel
271 1.1.1.2 kardel Options are specified by doubled hyphens and their name or by a single
272 1.1.1.2 kardel hyphen and the flag character.
273 1.1.1.2 kardel
274 1.1.1.2 kardel
275 1.1.1.2 kardel The following option preset mechanisms are supported:
276 1.1.1.2 kardel - reading file $HOME/.ntprc
277 1.1.1.2 kardel - reading file ./.ntprc
278 1.1.1.2 kardel - examining environment variables named SNTP_*
279 1.1.1.2 kardel
280 1.1.1.17 christos Please send bug reports to: <https://bugs.ntp.org, bugs (a] ntp.org>
281 1.1.1.15 christos </pre></div>
282 1.1.1.2 kardel
283 1.1.1.15 christos <hr>
284 1.1.1.17 christos <span id="sntp-ipv4"></span><div class="header">
285 1.1.1.15 christos <p>
286 1.1.1.15 christos Next: <a href="#sntp-ipv6" accesskey="n" rel="next">sntp ipv6</a>, Previous: <a href="#sntp-usage" accesskey="p" rel="prev">sntp usage</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
287 1.1.1.15 christos </div>
288 1.1.1.17 christos <span id="ipv4-option-_0028_002d4_0029"></span><h4 class="subsection">1.1.2 ipv4 option (-4)</h4>
289 1.1.1.17 christos <span id="index-sntp_002dipv4"></span>
290 1.1.1.15 christos
291 1.1.1.15 christos <p>This is the “force ipv4 dns name resolution” option.
292 1.1.1.15 christos </p>
293 1.1.1.15 christos <p>This option has some usage constraints. It:
294 1.1.1.15 christos </p><ul>
295 1.1.1.15 christos <li> must not appear in combination with any of the following options:
296 1.1.1.15 christos ipv6.
297 1.1.1.15 christos </li></ul>
298 1.1.1.15 christos
299 1.1.1.15 christos <p>Force DNS resolution of the following host names on the command line
300 1.1.1.15 christos to the IPv4 namespace.
301 1.1.1.15 christos </p><hr>
302 1.1.1.17 christos <span id="sntp-ipv6"></span><div class="header">
303 1.1.1.15 christos <p>
304 1.1.1.15 christos Next: <a href="#sntp-authentication" accesskey="n" rel="next">sntp authentication</a>, Previous: <a href="#sntp-ipv4" accesskey="p" rel="prev">sntp ipv4</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
305 1.1.1.15 christos </div>
306 1.1.1.17 christos <span id="ipv6-option-_0028_002d6_0029"></span><h4 class="subsection">1.1.3 ipv6 option (-6)</h4>
307 1.1.1.17 christos <span id="index-sntp_002dipv6"></span>
308 1.1.1.15 christos
309 1.1.1.15 christos <p>This is the “force ipv6 dns name resolution” option.
310 1.1.1.15 christos </p>
311 1.1.1.15 christos <p>This option has some usage constraints. It:
312 1.1.1.15 christos </p><ul>
313 1.1.1.15 christos <li> must not appear in combination with any of the following options:
314 1.1.1.15 christos ipv4.
315 1.1.1.15 christos </li></ul>
316 1.1.1.15 christos
317 1.1.1.15 christos <p>Force DNS resolution of the following host names on the command line
318 1.1.1.15 christos to the IPv6 namespace.
319 1.1.1.15 christos </p><hr>
320 1.1.1.17 christos <span id="sntp-authentication"></span><div class="header">
321 1.1.1.15 christos <p>
322 1.1.1.15 christos Next: <a href="#sntp-broadcast" accesskey="n" rel="next">sntp broadcast</a>, Previous: <a href="#sntp-ipv6" accesskey="p" rel="prev">sntp ipv6</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
323 1.1.1.15 christos </div>
324 1.1.1.17 christos <span id="authentication-option-_0028_002da_0029"></span><h4 class="subsection">1.1.4 authentication option (-a)</h4>
325 1.1.1.17 christos <span id="index-sntp_002dauthentication"></span>
326 1.1.1.15 christos
327 1.1.1.15 christos <p>This is the “enable authentication with the key <var>auth-keynumber</var>” option.
328 1.1.1.15 christos This option takes a number argument <samp>auth-keynumber</samp>.
329 1.1.1.15 christos Enable authentication using the key specified in this option’s
330 1.1.1.15 christos argument. The argument of this option is the <samp>keyid</samp>, a
331 1.1.1.15 christos number specified in the <samp>keyfile</samp> as this key’s identifier.
332 1.1.1.15 christos See the <samp>keyfile</samp> option (<samp>-k</samp>) for more details.
333 1.1.1.15 christos </p><hr>
334 1.1.1.17 christos <span id="sntp-broadcast"></span><div class="header">
335 1.1.1.15 christos <p>
336 1.1.1.15 christos Next: <a href="#sntp-concurrent" accesskey="n" rel="next">sntp concurrent</a>, Previous: <a href="#sntp-authentication" accesskey="p" rel="prev">sntp authentication</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
337 1.1.1.15 christos </div>
338 1.1.1.17 christos <span id="broadcast-option-_0028_002db_0029"></span><h4 class="subsection">1.1.5 broadcast option (-b)</h4>
339 1.1.1.17 christos <span id="index-sntp_002dbroadcast"></span>
340 1.1.1.15 christos
341 1.1.1.15 christos <p>This is the “listen to the address specified for broadcast time sync” option.
342 1.1.1.15 christos This option takes a string argument <samp>broadcast-address</samp>.
343 1.1.1.15 christos </p>
344 1.1.1.15 christos <p>This option has some usage constraints. It:
345 1.1.1.15 christos </p><ul>
346 1.1.1.15 christos <li> may appear an unlimited number of times.
347 1.1.1.15 christos </li></ul>
348 1.1.1.2 kardel
349 1.1.1.15 christos <p>If specified <code>sntp</code> will listen to the specified address
350 1.1.1.3 christos for NTP broadcasts. The default maximum wait time
351 1.1.1.15 christos can (and probably should) be modified with <samp>-t</samp>.
352 1.1.1.15 christos </p><hr>
353 1.1.1.17 christos <span id="sntp-concurrent"></span><div class="header">
354 1.1.1.15 christos <p>
355 1.1.1.15 christos Next: <a href="#sntp-gap" accesskey="n" rel="next">sntp gap</a>, Previous: <a href="#sntp-broadcast" accesskey="p" rel="prev">sntp broadcast</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
356 1.1.1.15 christos </div>
357 1.1.1.17 christos <span id="concurrent-option-_0028_002dc_0029"></span><h4 class="subsection">1.1.6 concurrent option (-c)</h4>
358 1.1.1.17 christos <span id="index-sntp_002dconcurrent"></span>
359 1.1.1.15 christos
360 1.1.1.15 christos <p>This is the “concurrently query all ips returned for host-name” option.
361 1.1.1.15 christos This option takes a string argument <samp>host-name</samp>.
362 1.1.1.15 christos </p>
363 1.1.1.15 christos <p>This option has some usage constraints. It:
364 1.1.1.15 christos </p><ul>
365 1.1.1.15 christos <li> may appear an unlimited number of times.
366 1.1.1.15 christos </li></ul>
367 1.1.1.2 kardel
368 1.1.1.15 christos <p>Requests from an NTP "client" to a "server" should never be sent
369 1.1.1.3 christos more rapidly than one every 2 seconds. By default, any IPs returned
370 1.1.1.3 christos as part of a DNS lookup are assumed to be for a single instance of
371 1.1.1.3 christos <code>ntpd</code>, and therefore <code>sntp</code> will send queries to these IPs
372 1.1.1.3 christos one after another, with a 2-second gap in between each query.
373 1.1.1.15 christos </p>
374 1.1.1.15 christos <p>The <samp>-c</samp> or <samp>--concurrent</samp> flag says that any IPs
375 1.1.1.3 christos returned for the DNS lookup of the supplied host-name are on
376 1.1.1.15 christos different machines, so we can send concurrent queries.
377 1.1.1.15 christos </p><hr>
378 1.1.1.17 christos <span id="sntp-gap"></span><div class="header">
379 1.1.1.15 christos <p>
380 1.1.1.15 christos Next: <a href="#sntp-kod" accesskey="n" rel="next">sntp kod</a>, Previous: <a href="#sntp-concurrent" accesskey="p" rel="prev">sntp concurrent</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
381 1.1.1.15 christos </div>
382 1.1.1.17 christos <span id="gap-option-_0028_002dg_0029"></span><h4 class="subsection">1.1.7 gap option (-g)</h4>
383 1.1.1.17 christos <span id="index-sntp_002dgap"></span>
384 1.1.1.15 christos
385 1.1.1.15 christos <p>This is the “the gap (in milliseconds) between time requests” option.
386 1.1.1.15 christos This option takes a number argument <samp>milliseconds</samp>.
387 1.1.1.15 christos Since we’re only going to use the first valid response we get and
388 1.1.1.3 christos there is benefit to specifying a good number of servers to query,
389 1.1.1.3 christos separate the queries we send out by the specified number of
390 1.1.1.15 christos milliseconds.
391 1.1.1.15 christos </p><hr>
392 1.1.1.17 christos <span id="sntp-kod"></span><div class="header">
393 1.1.1.15 christos <p>
394 1.1.1.15 christos Next: <a href="#sntp-keyfile" accesskey="n" rel="next">sntp keyfile</a>, Previous: <a href="#sntp-gap" accesskey="p" rel="prev">sntp gap</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
395 1.1.1.15 christos </div>
396 1.1.1.17 christos <span id="kod-option-_0028_002dK_0029"></span><h4 class="subsection">1.1.8 kod option (-K)</h4>
397 1.1.1.17 christos <span id="index-sntp_002dkod"></span>
398 1.1.1.2 kardel
399 1.1.1.15 christos <p>This is the “kod history filename” option.
400 1.1.1.15 christos This option takes a file argument <samp>file-name</samp>.
401 1.1.1.3 christos Specifies the filename to be used for the persistent history of KoD
402 1.1.1.4 christos responses received from servers. If the file does not exist, a
403 1.1.1.15 christos warning message will be displayed. The file will not be created.
404 1.1.1.15 christos </p><hr>
405 1.1.1.17 christos <span id="sntp-keyfile"></span><div class="header">
406 1.1.1.15 christos <p>
407 1.1.1.15 christos Next: <a href="#sntp-logfile" accesskey="n" rel="next">sntp logfile</a>, Previous: <a href="#sntp-kod" accesskey="p" rel="prev">sntp kod</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
408 1.1.1.15 christos </div>
409 1.1.1.17 christos <span id="keyfile-option-_0028_002dk_0029"></span><h4 class="subsection">1.1.9 keyfile option (-k)</h4>
410 1.1.1.17 christos <span id="index-sntp_002dkeyfile"></span>
411 1.1.1.15 christos
412 1.1.1.15 christos <p>This is the “look in this file for the key specified with <samp>-a</samp>” option.
413 1.1.1.15 christos This option takes a file argument <samp>file-name</samp>.
414 1.1.1.15 christos This option specifies the keyfile.
415 1.1.1.15 christos <code>sntp</code> will search for the key specified with <samp>-a</samp>
416 1.1.1.15 christos <samp>keyno</samp> in this file. See <code>ntp.keys(5)</code> for more
417 1.1.1.15 christos information.
418 1.1.1.15 christos </p><hr>
419 1.1.1.17 christos <span id="sntp-logfile"></span><div class="header">
420 1.1.1.15 christos <p>
421 1.1.1.15 christos Next: <a href="#sntp-steplimit" accesskey="n" rel="next">sntp steplimit</a>, Previous: <a href="#sntp-keyfile" accesskey="p" rel="prev">sntp keyfile</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
422 1.1.1.15 christos </div>
423 1.1.1.17 christos <span id="logfile-option-_0028_002dl_0029"></span><h4 class="subsection">1.1.10 logfile option (-l)</h4>
424 1.1.1.17 christos <span id="index-sntp_002dlogfile"></span>
425 1.1.1.15 christos
426 1.1.1.15 christos <p>This is the “log to specified logfile” option.
427 1.1.1.15 christos This option takes a file argument <samp>file-name</samp>.
428 1.1.1.3 christos This option causes the client to write log messages to the specified
429 1.1.1.15 christos <samp>logfile</samp>.
430 1.1.1.15 christos </p><hr>
431 1.1.1.17 christos <span id="sntp-steplimit"></span><div class="header">
432 1.1.1.15 christos <p>
433 1.1.1.15 christos Next: <a href="#sntp-ntpversion" accesskey="n" rel="next">sntp ntpversion</a>, Previous: <a href="#sntp-logfile" accesskey="p" rel="prev">sntp logfile</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
434 1.1.1.15 christos </div>
435 1.1.1.17 christos <span id="steplimit-option-_0028_002dM_0029"></span><h4 class="subsection">1.1.11 steplimit option (-M)</h4>
436 1.1.1.17 christos <span id="index-sntp_002dsteplimit"></span>
437 1.1.1.15 christos
438 1.1.1.15 christos <p>This is the “adjustments less than <var>steplimit</var> msec will be slewed” option.
439 1.1.1.15 christos This option takes a number argument.
440 1.1.1.15 christos If the time adjustment is less than <samp>steplimit</samp> milliseconds,
441 1.1.1.15 christos slew the amount using <code>adjtime(2)</code>. Otherwise, step the
442 1.1.1.15 christos correction using <code>settimeofday(2)</code>. The default value is 0,
443 1.1.1.5 christos which means all adjustments will be stepped. This is a feature, as
444 1.1.1.15 christos different situations demand different values.
445 1.1.1.15 christos </p><hr>
446 1.1.1.17 christos <span id="sntp-ntpversion"></span><div class="header">
447 1.1.1.15 christos <p>
448 1.1.1.15 christos Next: <a href="#sntp-usereservedport" accesskey="n" rel="next">sntp usereservedport</a>, Previous: <a href="#sntp-steplimit" accesskey="p" rel="prev">sntp steplimit</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
449 1.1.1.15 christos </div>
450 1.1.1.17 christos <span id="ntpversion-option-_0028_002do_0029"></span><h4 class="subsection">1.1.12 ntpversion option (-o)</h4>
451 1.1.1.17 christos <span id="index-sntp_002dntpversion"></span>
452 1.1.1.2 kardel
453 1.1.1.15 christos <p>This is the “send <var>int</var> as our ntp protocol version” option.
454 1.1.1.15 christos This option takes a number argument.
455 1.1.1.3 christos When sending requests to a remote server, tell them we are running
456 1.1.1.15 christos NTP protocol version <samp>ntpversion</samp> .
457 1.1.1.15 christos </p><hr>
458 1.1.1.17 christos <span id="sntp-usereservedport"></span><div class="header">
459 1.1.1.15 christos <p>
460 1.1.1.15 christos Next: <a href="#sntp-timeout" accesskey="n" rel="next">sntp timeout</a>, Previous: <a href="#sntp-ntpversion" accesskey="p" rel="prev">sntp ntpversion</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
461 1.1.1.15 christos </div>
462 1.1.1.17 christos <span id="usereservedport-option-_0028_002dr_0029"></span><h4 class="subsection">1.1.13 usereservedport option (-r)</h4>
463 1.1.1.17 christos <span id="index-sntp_002dusereservedport"></span>
464 1.1.1.2 kardel
465 1.1.1.15 christos <p>This is the “use the ntp reserved port (port 123)” option.
466 1.1.1.3 christos Use port 123, which is reserved for NTP, for our network
467 1.1.1.15 christos communications.
468 1.1.1.15 christos </p><hr>
469 1.1.1.17 christos <span id="sntp-timeout"></span><div class="header">
470 1.1.1.15 christos <p>
471 1.1.1.15 christos Next: <a href="#sntp-wait" accesskey="n" rel="next">sntp wait</a>, Previous: <a href="#sntp-usereservedport" accesskey="p" rel="prev">sntp usereservedport</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
472 1.1.1.15 christos </div>
473 1.1.1.17 christos <span id="timeout-option-_0028_002dt_0029"></span><h4 class="subsection">1.1.14 timeout option (-t)</h4>
474 1.1.1.17 christos <span id="index-sntp_002dtimeout"></span>
475 1.1.1.3 christos
476 1.1.1.15 christos <p>This is the “the number of seconds to wait for responses” option.
477 1.1.1.15 christos This option takes a number argument <samp>seconds</samp>.
478 1.1.1.3 christos When waiting for a reply, <code>sntp</code> will wait the number
479 1.1.1.3 christos of seconds specified before giving up. The default should be
480 1.1.1.3 christos more than enough for a unicast response. If <code>sntp</code> is
481 1.1.1.3 christos only waiting for a broadcast response a longer timeout is
482 1.1.1.15 christos likely needed.
483 1.1.1.15 christos </p><hr>
484 1.1.1.17 christos <span id="sntp-wait"></span><div class="header">
485 1.1.1.15 christos <p>
486 1.1.1.15 christos Next: <a href="#sntp-config" accesskey="n" rel="next">sntp config</a>, Previous: <a href="#sntp-timeout" accesskey="p" rel="prev">sntp timeout</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
487 1.1.1.15 christos </div>
488 1.1.1.17 christos <span id="wait-option"></span><h4 class="subsection">1.1.15 wait option</h4>
489 1.1.1.17 christos <span id="index-sntp_002dwait"></span>
490 1.1.1.15 christos
491 1.1.1.15 christos <p>This is the “wait for pending replies (if not setting the time)” option.
492 1.1.1.15 christos </p>
493 1.1.1.15 christos <p>This option has some usage constraints. It:
494 1.1.1.15 christos </p><ul>
495 1.1.1.15 christos <li> can be disabled with –no-wait.
496 1.1.1.15 christos </li><li> It is enabled by default.
497 1.1.1.15 christos </li></ul>
498 1.1.1.15 christos
499 1.1.1.15 christos <p>If we are not setting the time, wait for all pending responses.
500 1.1.1.15 christos </p>
501 1.1.1.15 christos
502 1.1.1.15 christos <hr>
503 1.1.1.17 christos <span id="sntp-config"></span><div class="header">
504 1.1.1.15 christos <p>
505 1.1.1.15 christos Next: <a href="#sntp-exit-status" accesskey="n" rel="next">sntp exit status</a>, Previous: <a href="#sntp-wait" accesskey="p" rel="prev">sntp wait</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
506 1.1.1.2 kardel </div>
507 1.1.1.17 christos <span id="presetting_002fconfiguring-sntp"></span><h4 class="subsection">1.1.16 presetting/configuring sntp</h4>
508 1.1.1.2 kardel
509 1.1.1.3 christos <p>Any option that is not marked as <i>not presettable</i> may be preset by
510 1.1.1.15 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
511 1.1.1.15 christos the options listed above in upper case and segmented with underscores.
512 1.1.1.3 christos The <code>SNTP</code> variable will be tokenized and parsed like
513 1.1.1.3 christos the command line. The remaining variables are tested for existence and their
514 1.1.1.3 christos values are treated like option arguments.
515 1.1.1.15 christos </p>
516 1.1.1.2 kardel
517 1.1.1.15 christos <p><code>libopts</code> will search in 2 places for configuration files:
518 1.1.1.15 christos </p><ul>
519 1.1.1.15 christos <li> $HOME
520 1.1.1.15 christos </li><li> $PWD
521 1.1.1.15 christos </li></ul>
522 1.1.1.15 christos <p>The environment variables <code>HOME</code>, and <code>PWD</code>
523 1.1.1.15 christos are expanded and replaced when <samp>sntp</samp> runs.
524 1.1.1.15 christos For any of these that are plain files, they are simply processed.
525 1.1.1.15 christos For any that are directories, then a file named <samp>.ntprc</samp> is searched for
526 1.1.1.3 christos within that directory and processed.
527 1.1.1.15 christos </p>
528 1.1.1.15 christos <p>Configuration files may be in a wide variety of formats.
529 1.1.1.3 christos The basic format is an option name followed by a value (argument) on the
530 1.1.1.3 christos same line. Values may be separated from the option name with a colon,
531 1.1.1.3 christos equal sign or simply white space. Values may be continued across multiple
532 1.1.1.3 christos lines by escaping the newline with a backslash.
533 1.1.1.15 christos </p>
534 1.1.1.15 christos <p>Multiple programs may also share the same initialization file.
535 1.1.1.3 christos Common options are collected at the top, followed by program specific
536 1.1.1.3 christos segments. The segments are separated by lines like:
537 1.1.1.15 christos </p><div class="example">
538 1.1.1.15 christos <pre class="example">[SNTP]
539 1.1.1.15 christos </pre></div>
540 1.1.1.15 christos <p>or by
541 1.1.1.15 christos </p><div class="example">
542 1.1.1.15 christos <pre class="example"><?program sntp>
543 1.1.1.15 christos </pre></div>
544 1.1.1.15 christos <p>Do not mix these styles within one configuration file.
545 1.1.1.15 christos </p>
546 1.1.1.15 christos <p>Compound values and carefully constructed string values may also be
547 1.1.1.3 christos specified using XML syntax:
548 1.1.1.15 christos </p><div class="example">
549 1.1.1.15 christos <pre class="example"><option-name>
550 1.1.1.15 christos <sub-opt>...&lt;...&gt;...</sub-opt>
551 1.1.1.15 christos </option-name>
552 1.1.1.15 christos </pre></div>
553 1.1.1.15 christos <p>yielding an <code>option-name.sub-opt</code> string value of
554 1.1.1.15 christos </p><div class="example">
555 1.1.1.15 christos <pre class="example">"...<...>..."
556 1.1.1.15 christos </pre></div>
557 1.1.1.15 christos <p><code>AutoOpts</code> does not track suboptions. You simply note that it is a
558 1.1.1.3 christos hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching
559 1.1.1.3 christos the associated name/value pair list (see: optionFindValue).
560 1.1.1.15 christos </p>
561 1.1.1.15 christos <p>The command line options relating to configuration and/or usage help are:
562 1.1.1.15 christos </p>
563 1.1.1.17 christos <span id="version-_0028_002d_0029"></span><h4 class="subsubheading">version (-)</h4>
564 1.1.1.3 christos
565 1.1.1.3 christos <p>Print the program version to standard out, optionally with licensing
566 1.1.1.3 christos information, then exit 0. The optional argument specifies how much licensing
567 1.1.1.17 christos detail to provide. The default is to print just the version. The licensing information may be selected with an option argument.
568 1.1.1.3 christos Only the first letter of the argument is examined:
569 1.1.1.15 christos </p>
570 1.1.1.15 christos <dl compact="compact">
571 1.1.1.15 christos <dt>‘<samp>version</samp>’</dt>
572 1.1.1.15 christos <dd><p>Only print the version. This is the default.
573 1.1.1.15 christos </p></dd>
574 1.1.1.15 christos <dt>‘<samp>copyright</samp>’</dt>
575 1.1.1.15 christos <dd><p>Name the copyright usage licensing terms.
576 1.1.1.15 christos </p></dd>
577 1.1.1.15 christos <dt>‘<samp>verbose</samp>’</dt>
578 1.1.1.15 christos <dd><p>Print the full copyright usage licensing terms.
579 1.1.1.15 christos </p></dd>
580 1.1.1.3 christos </dl>
581 1.1.1.2 kardel
582 1.1.1.15 christos <hr>
583 1.1.1.17 christos <span id="sntp-exit-status"></span><div class="header">
584 1.1.1.15 christos <p>
585 1.1.1.15 christos Next: <a href="#sntp-Usage" accesskey="n" rel="next">sntp Usage</a>, Previous: <a href="#sntp-config" accesskey="p" rel="prev">sntp config</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
586 1.1.1.2 kardel </div>
587 1.1.1.17 christos <span id="sntp-exit-status-1"></span><h4 class="subsection">1.1.17 sntp exit status</h4>
588 1.1.1.3 christos
589 1.1.1.3 christos <p>One of the following exit values will be returned:
590 1.1.1.15 christos </p><dl compact="compact">
591 1.1.1.15 christos <dt>‘<samp>0 (EXIT_SUCCESS)</samp>’</dt>
592 1.1.1.15 christos <dd><p>Successful program execution.
593 1.1.1.15 christos </p></dd>
594 1.1.1.15 christos <dt>‘<samp>1 (EXIT_FAILURE)</samp>’</dt>
595 1.1.1.15 christos <dd><p>The operation failed or the command syntax was not valid.
596 1.1.1.15 christos </p></dd>
597 1.1.1.15 christos <dt>‘<samp>66 (EX_NOINPUT)</samp>’</dt>
598 1.1.1.15 christos <dd><p>A specified configuration file could not be loaded.
599 1.1.1.15 christos </p></dd>
600 1.1.1.15 christos <dt>‘<samp>70 (EX_SOFTWARE)</samp>’</dt>
601 1.1.1.15 christos <dd><p>libopts had an internal operational error. Please report
602 1.1.1.15 christos it to autogen-users (a] lists.sourceforge.net. Thank you.
603 1.1.1.15 christos </p></dd>
604 1.1.1.3 christos </dl>
605 1.1.1.15 christos <hr>
606 1.1.1.17 christos <span id="sntp-Usage"></span><div class="header">
607 1.1.1.15 christos <p>
608 1.1.1.15 christos Next: <a href="#sntp-Authors" accesskey="n" rel="next">sntp Authors</a>, Previous: <a href="#sntp-exit-status" accesskey="p" rel="prev">sntp exit status</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
609 1.1.1.15 christos </div>
610 1.1.1.17 christos <span id="sntp-Usage-1"></span><h4 class="subsection">1.1.18 sntp Usage</h4>
611 1.1.1.15 christos <hr>
612 1.1.1.17 christos <span id="sntp-Authors"></span><div class="header">
613 1.1.1.15 christos <p>
614 1.1.1.15 christos Previous: <a href="#sntp-Usage" accesskey="p" rel="prev">sntp Usage</a>, Up: <a href="#sntp-Invocation" accesskey="u" rel="up">sntp Invocation</a> </p>
615 1.1.1.3 christos </div>
616 1.1.1.17 christos <span id="sntp-Authors-1"></span><h4 class="subsection">1.1.19 sntp Authors</h4>
617 1.1.1.3 christos
618 1.1.1.15 christos <hr>
619 1.1.1.17 christos <span id="Usage"></span><div class="header">
620 1.1.1.15 christos <p>
621 1.1.1.15 christos Previous: <a href="#sntp-Invocation" accesskey="p" rel="prev">sntp Invocation</a>, Up: <a href="#sntp-Description" accesskey="u" rel="up">sntp Description</a> </p>
622 1.1 kardel </div>
623 1.1.1.17 christos <span id="Usage-1"></span><h3 class="section">1.2 Usage</h3>
624 1.1 kardel
625 1.1 kardel <p>The simplest use of this program is as an unprivileged command to
626 1.1.1.15 christos check the current time, offset, and error in the local clock.
627 1.1 kardel For example:
628 1.1.1.15 christos </p>
629 1.1.1.15 christos <div class="example">
630 1.1.1.15 christos <pre class="example">sntp ntpserver.somewhere
631 1.1.1.15 christos </pre></div>
632 1.1 kardel
633 1.1.1.15 christos <p>With suitable privilege, it can be run as a command or in a
634 1.1 kardel <code>crom</code> job to reset the local clock from a reliable server, like
635 1.1.1.15 christos the <code>ntpdate</code> and <code>rdate</code> commands.
636 1.1 kardel For example:
637 1.1.1.15 christos </p>
638 1.1.1.15 christos <div class="example">
639 1.1.1.15 christos <pre class="example">sntp -a ntpserver.somewhere
640 1.1.1.15 christos </pre></div>
641 1.1.1.15 christos <hr>
642 1.1.1.15 christos
643 1.1 kardel
644 1.1 kardel
645 1.1.1.15 christos </body>
646 1.1.1.15 christos </html>
647