1<html lang="en"> 2<head> 3<title>Sntp User's Manual</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Sntp User's Manual"> 6<meta name="generator" content="makeinfo 4.7"> 7<link title="Top" rel="top" href="#Top"> 8<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 9<meta http-equiv="Content-Style-Type" content="text/css"> 10<style type="text/css"><!-- 11 pre.display { font-family:inherit } 12 pre.format { font-family:inherit } 13 pre.smalldisplay { font-family:inherit; font-size:smaller } 14 pre.smallformat { font-family:inherit; font-size:smaller } 15 pre.smallexample { font-size:smaller } 16 pre.smalllisp { font-size:smaller } 17 span.sc { font-variant:small-caps } 18 span.roman { font-family: serif; font-weight: normal; } 19--></style> 20</head> 21<body> 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>, 26Previous: <a rel="previous" accesskey="p" href="#dir">(dir)</a>, 27Up: <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, 34that can be used to query a Network Time Protocol (NTP) server and 35display the time offset of the system clock relative to the server 36clock. Run as root, it can correct the system clock to this offset as 37well. It can be run as an interactive command or from a cron job. 38 39 <p>This document applies to version 4.2.8p1 of <code>sntp</code>. 40 41 <p>The program implements the SNTP protocol as defined by RFC 5905, the NTPv4 42IETF 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 67standard 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 72YYYY-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), 74and 75the +4.567 +/- 0.089 secs indicates the time offset and 76error 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> 89can be used as an SNTP client to query a NTP or SNTP server and either display 90the time or set the local system's time (given suitable privilege). It can be 91run as an interactive command or from a 92<code>cron</code> 93job. 94 95 <p>NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol) 96are defined and described by RFC 5905. 97 98 <p>The default is to write the estimated correct local date and time (i.e. not 99UTC) 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> 105means that to get to UTC from the reported local time one must 106add 8 hours and 0 minutes, 107the 108<code>'+4.567'</code> 109indicates 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). 111Note that the number of decimals printed for this value will change 112based on the reported precision of the server. 113<code>'+/- 0.089'</code> 114is the reported 115<em>synchronization</em> <em>distance</em> 116(in seconds), which represents the maximum error due to all causes. 117If the server does not report valid data needed to calculate the 118synchronization distance, this will be reported as 119<code>'+/- ?'</code>. 120If the 121<em>host</em> 122is different from the 123<em>IP</em>, 124both will be displayed. 125Otherwise, only the 126<em>IP</em> 127is displayed. 128Finally, the 129<em>stratum</em> 130of the host is reported. 131 132 <p>This section was generated by <strong>AutoGen</strong>, 133using the <code>agtexi-cmd</code> template and the option descriptions for the <code>sntp</code> program. 134This 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>, 161Up: <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> 168This 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 172the 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 175used to select the program, defaulting to <span class="file">more</span>. Both will exit 176with a status code of 0. 177 178<pre class="example">sntp - standard Simple Network Time Protocol client program - Ver. 4.2.8p1 179Usage: 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 220Options are specified by doubled hyphens and their name or by a single 221hyphen and the flag character. 222 223 224The following option preset mechanisms are supported: 225 - reading file $HOME/.ntprc 226 - reading file ./.ntprc 227 - examining environment variables named SNTP_* 228 229Please send bug reports to: <http://bugs.ntp.org, bugs@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>, 234Previous: <a rel="previous" accesskey="p" href="#sntp-usage">sntp usage</a>, 235Up: <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> 242This 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: 247ipv6. 248</ul> 249 250 <p>Force DNS resolution of the following host names on the command line 251to 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>, 255Previous: <a rel="previous" accesskey="p" href="#sntp-ipv4">sntp ipv4</a>, 256Up: <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> 263This 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: 268ipv4. 269</ul> 270 271 <p>Force DNS resolution of the following host names on the command line 272to 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>, 276Previous: <a rel="previous" accesskey="p" href="#sntp-ipv6">sntp ipv6</a>, 277Up: <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> 284This is the “enable authentication with the key <var>auth-keynumber</var>” option. 285This option takes a number argument <span class="file">auth-keynumber</span>. 286Enable authentication using the key specified in this option's 287argument. The argument of this option is the <span class="option">keyid</span>, a 288number specified in the <span class="option">keyfile</span> as this key's identifier. 289See 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>, 293Previous: <a rel="previous" accesskey="p" href="#sntp-authentication">sntp authentication</a>, 294Up: <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> 301This is the “listen to the address specified for broadcast time sync” option. 302This 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 310for NTP broadcasts. The default maximum wait time 311can (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>, 315Previous: <a rel="previous" accesskey="p" href="#sntp-broadcast">sntp broadcast</a>, 316Up: <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> 323This is the “concurrently query all ips returned for host-name” option. 324This 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 332more rapidly than one every 2 seconds. By default, any IPs returned 333as 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 335one 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 338returned for the DNS lookup of the supplied host-name are on 339different 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>, 343Previous: <a rel="previous" accesskey="p" href="#sntp-concurrent">sntp concurrent</a>, 344Up: <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> 351This is the “the gap (in milliseconds) between time requests” option. 352This option takes a number argument <span class="file">milliseconds</span>. 353Since we're only going to use the first valid response we get and 354there is benefit to specifying a good number of servers to query, 355separate the queries we send out by the specified number of 356milliseconds. 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>, 360Previous: <a rel="previous" accesskey="p" href="#sntp-gap">sntp gap</a>, 361Up: <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> 368This is the “kod history filename” option. 369This option takes a file argument <span class="file">file-name</span>. 370Specifies the filename to be used for the persistent history of KoD 371responses received from servers. If the file does not exist, a 372warning 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>, 376Previous: <a rel="previous" accesskey="p" href="#sntp-kod">sntp kod</a>, 377Up: <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> 384This is the “look in this file for the key specified with <span class="option">-a</span>” option. 385This option takes a file argument <span class="file">file-name</span>. 386This 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 389information. 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>, 393Previous: <a rel="previous" accesskey="p" href="#sntp-keyfile">sntp keyfile</a>, 394Up: <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> 401This is the “log to specified logfile” option. 402This option takes a file argument <span class="file">file-name</span>. 403This 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>, 408Previous: <a rel="previous" accesskey="p" href="#sntp-logfile">sntp logfile</a>, 409Up: <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> 416This is the “adjustments less than <var>steplimit</var> msec will be slewed” option. 417This option takes a number argument. 418If the time adjustment is less than <span class="file">steplimit</span> milliseconds, 419slew the amount using <span class="command">adjtime(2)</span>. Otherwise, step the 420correction using <span class="command">settimeofday(2)</span>. The default value is 0, 421which means all adjustments will be stepped. This is a feature, as 422different situations demand different values. 423<div class="node"> 424<p><hr> 425<a name="sntp-ntpversion"></a>Next: <a rel="next" accesskey="n" href="#sntp-usereservedport">sntp usereservedport</a>, 426Previous: <a rel="previous" accesskey="p" href="#sntp-steplimit">sntp steplimit</a>, 427Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 428<br> 429</div> 430 431<h4 class="subsection">ntpversion option (-o)</h4> 432 433<p><a name="index-sntp_002dntpversion-14"></a> 434This is the “send <var>int</var> as our ntp protocol version” option. 435This option takes a number argument. 436When sending requests to a remote server, tell them we are running 437NTP protocol version <span class="file">ntpversion</span> . 438<div class="node"> 439<p><hr> 440<a name="sntp-usereservedport"></a>Next: <a rel="next" accesskey="n" href="#sntp-timeout">sntp timeout</a>, 441Previous: <a rel="previous" accesskey="p" href="#sntp-ntpversion">sntp ntpversion</a>, 442Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 443<br> 444</div> 445 446<h4 class="subsection">usereservedport option (-r)</h4> 447 448<p><a name="index-sntp_002dusereservedport-15"></a> 449This is the “use the ntp reserved port (port 123)” option. 450Use port 123, which is reserved for NTP, for our network 451communications. 452<div class="node"> 453<p><hr> 454<a name="sntp-timeout"></a>Next: <a rel="next" accesskey="n" href="#sntp-wait">sntp wait</a>, 455Previous: <a rel="previous" accesskey="p" href="#sntp-usereservedport">sntp usereservedport</a>, 456Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 457<br> 458</div> 459 460<h4 class="subsection">timeout option (-t)</h4> 461 462<p><a name="index-sntp_002dtimeout-16"></a> 463This is the “the number of seconds to wait for responses” option. 464This option takes a number argument <span class="file">seconds</span>. 465When waiting for a reply, <code>sntp</code> will wait the number 466of seconds specified before giving up. The default should be 467more than enough for a unicast response. If <code>sntp</code> is 468only waiting for a broadcast response a longer timeout is 469likely needed. 470<div class="node"> 471<p><hr> 472<a name="sntp-wait"></a>Next: <a rel="next" accesskey="n" href="#sntp-config">sntp config</a>, 473Previous: <a rel="previous" accesskey="p" href="#sntp-timeout">sntp timeout</a>, 474Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 475<br> 476</div> 477 478<h4 class="subsection">wait option</h4> 479 480<p><a name="index-sntp_002dwait-17"></a> 481This is the “wait for pending replies (if not setting the time)” option. 482 483<p class="noindent">This option has some usage constraints. It: 484 <ul> 485<li>can be disabled with –no-wait. 486<li>It is enabled by default. 487</ul> 488 489 <p>If we are not setting the time, wait for all pending responses. 490 491<div class="node"> 492<p><hr> 493<a name="sntp-config"></a>Next: <a rel="next" accesskey="n" href="#sntp-exit-status">sntp exit status</a>, 494Previous: <a rel="previous" accesskey="p" href="#sntp-wait">sntp wait</a>, 495Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 496<br> 497</div> 498 499<h4 class="subsection">presetting/configuring sntp</h4> 500 501<p>Any option that is not marked as <i>not presettable</i> may be preset by 502loading 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 503the options listed above in upper case and segmented with underscores. 504The <code>SNTP</code> variable will be tokenized and parsed like 505the command line. The remaining variables are tested for existence and their 506values are treated like option arguments. 507 508<p class="noindent"><code>libopts</code> will search in 2 places for configuration files: 509 <ul> 510<li>$HOME 511<li>$PWD 512</ul> 513 The environment variables <code>HOME</code>, and <code>PWD</code> 514are expanded and replaced when <span class="file">sntp</span> runs. 515For any of these that are plain files, they are simply processed. 516For any that are directories, then a file named <span class="file">.ntprc</span> is searched for 517within that directory and processed. 518 519 <p>Configuration files may be in a wide variety of formats. 520The basic format is an option name followed by a value (argument) on the 521same line. Values may be separated from the option name with a colon, 522equal sign or simply white space. Values may be continued across multiple 523lines by escaping the newline with a backslash. 524 525 <p>Multiple programs may also share the same initialization file. 526Common options are collected at the top, followed by program specific 527segments. The segments are separated by lines like: 528<pre class="example"> [SNTP] 529</pre> 530 <p class="noindent">or by 531<pre class="example"> <?program sntp> 532</pre> 533 <p class="noindent">Do not mix these styles within one configuration file. 534 535 <p>Compound values and carefully constructed string values may also be 536specified using XML syntax: 537<pre class="example"> <option-name> 538 <sub-opt>...&lt;...&gt;...</sub-opt> 539 </option-name> 540</pre> 541 <p class="noindent">yielding an <code>option-name.sub-opt</code> string value of 542<pre class="example"> "...<...>..." 543</pre> 544 <p><code>AutoOpts</code> does not track suboptions. You simply note that it is a 545hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching 546the associated name/value pair list (see: optionFindValue). 547 548 <p>The command line options relating to configuration and/or usage help are: 549 550<h5 class="subsubheading">version (-)</h5> 551 552<p>Print the program version to standard out, optionally with licensing 553information, then exit 0. The optional argument specifies how much licensing 554detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument. 555Only the first letter of the argument is examined: 556 557 <dl> 558<dt><span class="samp">version</span><dd>Only print the version. This is the default. 559<br><dt><span class="samp">copyright</span><dd>Name the copyright usage licensing terms. 560<br><dt><span class="samp">verbose</span><dd>Print the full copyright usage licensing terms. 561</dl> 562 563<div class="node"> 564<p><hr> 565<a name="sntp-exit-status"></a>Next: <a rel="next" accesskey="n" href="#sntp-Usage">sntp Usage</a>, 566Previous: <a rel="previous" accesskey="p" href="#sntp-config">sntp config</a>, 567Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 568<br> 569</div> 570 571<h4 class="subsection">sntp exit status</h4> 572 573<p>One of the following exit values will be returned: 574 <dl> 575<dt><span class="samp">0 (EXIT_SUCCESS)</span><dd>Successful program execution. 576<br><dt><span class="samp">1 (EXIT_FAILURE)</span><dd>The operation failed or the command syntax was not valid. 577<br><dt><span class="samp">66 (EX_NOINPUT)</span><dd>A specified configuration file could not be loaded. 578<br><dt><span class="samp">70 (EX_SOFTWARE)</span><dd>libopts had an internal operational error. Please report 579it to autogen-users@lists.sourceforge.net. Thank you. 580</dl> 581 <div class="node"> 582<p><hr> 583<a name="sntp-Usage"></a>Next: <a rel="next" accesskey="n" href="#sntp-Authors">sntp Authors</a>, 584Previous: <a rel="previous" accesskey="p" href="#sntp-exit-status">sntp exit status</a>, 585Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 586<br> 587</div> 588 589<h4 class="subsection">sntp Usage</h4> 590 591<div class="node"> 592<p><hr> 593<a name="sntp-Authors"></a>Previous: <a rel="previous" accesskey="p" href="#sntp-Usage">sntp Usage</a>, 594Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 595<br> 596</div> 597 598<h4 class="subsection">sntp Authors</h4> 599 600<div class="node"> 601<p><hr> 602<a name="Usage"></a> 603<br> 604</div> 605 606<!-- node-name, next, previous, up --> 607<h3 class="section">Usage</h3> 608 609<p>The simplest use of this program is as an unprivileged command to 610check the current time, offset, and error in the local clock. 611For example: 612 613<pre class="example"> sntp ntpserver.somewhere 614</pre> 615 <p>With suitable privilege, it can be run as a command or in a 616<code>crom</code> job to reset the local clock from a reliable server, like 617the <code>ntpdate</code> and <code>rdate</code> commands. 618For example: 619 620<pre class="example"> sntp -a ntpserver.somewhere 621</pre> 622 </body></html> 623 624