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 4.2.7p404 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<li><a href="#sntp-Notes">sntp Notes</a>: Notes 157</ul> 158 159<div class="node"> 160<p><hr> 161<a name="sntp-usage"></a>Next: <a rel="next" accesskey="n" href="#sntp-ipv4">sntp ipv4</a>, 162Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 163<br> 164</div> 165 166<h4 class="subsection">sntp help/usage (<span class="option">--help</span>)</h4> 167 168<p><a name="index-sntp-help-3"></a> 169This is the automatically generated usage text for sntp. 170 171 <p>The text printed is the same whether selected with the <code>help</code> option 172(<span class="option">--help</span>) or the <code>more-help</code> option (<span class="option">--more-help</span>). <code>more-help</code> will print 173the usage text by passing it through a pager program. 174<code>more-help</code> is disabled on platforms without a working 175<code>fork(2)</code> function. The <code>PAGER</code> environment variable is 176used to select the program, defaulting to <span class="file">more</span>. Both will exit 177with a status code of 0. 178 179<pre class="example">sntp - standard Simple Network Time Protocol client program - Ver. 4.2.7p404 180Usage: sntp [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \ 181 [ hostname-or-IP ...] 182 Flg Arg Option-Name Description 183 -4 no ipv4 Force IPv4 DNS name resolution 184 - prohibits the option 'ipv6' 185 -6 no ipv6 Force IPv6 DNS name resolution 186 - prohibits the option 'ipv4' 187 -a Num authentication Enable authentication with the key auth-keynumber 188 -b Str broadcast Listen to the address specified for broadcast time sync 189 - may appear multiple times 190 -c Str concurrent Concurrently query all IPs returned for host-name 191 - may appear multiple times 192 -d no debug-level Increase debug verbosity level 193 - may appear multiple times 194 -D Num set-debug-level Set the debug verbosity level 195 - may appear multiple times 196 -g Num gap The gap (in milliseconds) between time requests 197 -K Fil kod KoD history filename 198 -k Fil keyfile Look in this file for the key specified with -a 199 -l Fil logfile Log to specified logfile 200 -M Num steplimit Adjustments less than steplimit msec will be slewed 201 - it must be in the range: 202 greater than or equal to 0 203 -o Num ntpversion Send int as our NTP protocol version 204 - it must be in the range: 205 0 to 7 206 -r no usereservedport Use the NTP Reserved Port (port 123) 207 -S no step OK to 'step' the time with settimeofday(2) 208 -s no slew OK to 'slew' the time with adjtime(2) 209 -t Num timeout The number of seconds to wait for responses 210 no wait Wait for pending replies (if not setting the time) 211 - disabled as '--no-wait' 212 - enabled by default 213 opt version output version information and exit 214 -? no help display extended usage information and exit 215 -! no more-help extended usage information passed thru pager 216 -> opt save-opts save the option state to a config file 217 -< Str load-opts load options from a config file 218 - disabled as '--no-load-opts' 219 - may appear multiple times 220 221Options are specified by doubled hyphens and their name or by a single 222hyphen and the flag character. 223 224 225The following option preset mechanisms are supported: 226 - reading file $HOME/.ntprc 227 - reading file ./.ntprc 228 - examining environment variables named SNTP_* 229 230Please send bug reports to: <http://bugs.ntp.org, bugs@ntp.org> 231 232exit 0 233</pre> 234 <div class="node"> 235<p><hr> 236<a name="sntp-ipv4"></a>Next: <a rel="next" accesskey="n" href="#sntp-ipv6">sntp ipv6</a>, 237Previous: <a rel="previous" accesskey="p" href="#sntp-usage">sntp usage</a>, 238Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 239<br> 240</div> 241 242<h4 class="subsection">ipv4 option (-4)</h4> 243 244<p><a name="index-sntp_002dipv4-4"></a> 245This is the “force ipv4 dns name resolution” option. 246 247<p class="noindent">This option has some usage constraints. It: 248 <ul> 249<li>must not appear in combination with any of the following options: 250ipv6. 251</ul> 252 253 <p>Force DNS resolution of the following host names on the command line 254to the IPv4 namespace. 255<div class="node"> 256<p><hr> 257<a name="sntp-ipv6"></a>Next: <a rel="next" accesskey="n" href="#sntp-authentication">sntp authentication</a>, 258Previous: <a rel="previous" accesskey="p" href="#sntp-ipv4">sntp ipv4</a>, 259Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 260<br> 261</div> 262 263<h4 class="subsection">ipv6 option (-6)</h4> 264 265<p><a name="index-sntp_002dipv6-5"></a> 266This is the “force ipv6 dns name resolution” option. 267 268<p class="noindent">This option has some usage constraints. It: 269 <ul> 270<li>must not appear in combination with any of the following options: 271ipv4. 272</ul> 273 274 <p>Force DNS resolution of the following host names on the command line 275to the IPv6 namespace. 276<div class="node"> 277<p><hr> 278<a name="sntp-authentication"></a>Next: <a rel="next" accesskey="n" href="#sntp-broadcast">sntp broadcast</a>, 279Previous: <a rel="previous" accesskey="p" href="#sntp-ipv6">sntp ipv6</a>, 280Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 281<br> 282</div> 283 284<h4 class="subsection">authentication option (-a)</h4> 285 286<p><a name="index-sntp_002dauthentication-6"></a> 287This is the “enable authentication with the key <var>auth-keynumber</var>” option. 288This option takes a number argument <span class="file">auth-keynumber</span>. 289Enable authentication using the key specified in this option's 290argument. The argument of this option is the <span class="option">keyid</span>, a 291number specified in the <span class="option">keyfile</span> as this key's identifier. 292See the <span class="option">keyfile</span> option (<span class="option">-k</span>) for more details. 293<div class="node"> 294<p><hr> 295<a name="sntp-broadcast"></a>Next: <a rel="next" accesskey="n" href="#sntp-concurrent">sntp concurrent</a>, 296Previous: <a rel="previous" accesskey="p" href="#sntp-authentication">sntp authentication</a>, 297Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 298<br> 299</div> 300 301<h4 class="subsection">broadcast option (-b)</h4> 302 303<p><a name="index-sntp_002dbroadcast-7"></a> 304This is the “listen to the address specified for broadcast time sync” option. 305This option takes a string argument <span class="file">broadcast-address</span>. 306 307<p class="noindent">This option has some usage constraints. It: 308 <ul> 309<li>may appear an unlimited number of times. 310</ul> 311 312 <p>If specified <code>sntp</code> will listen to the specified address 313for NTP broadcasts. The default maximum wait time 314can (and probably should) be modified with <span class="option">-t</span>. 315<div class="node"> 316<p><hr> 317<a name="sntp-concurrent"></a>Next: <a rel="next" accesskey="n" href="#sntp-gap">sntp gap</a>, 318Previous: <a rel="previous" accesskey="p" href="#sntp-broadcast">sntp broadcast</a>, 319Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 320<br> 321</div> 322 323<h4 class="subsection">concurrent option (-c)</h4> 324 325<p><a name="index-sntp_002dconcurrent-8"></a> 326This is the “concurrently query all ips returned for host-name” option. 327This option takes a string argument <span class="file">host-name</span>. 328 329<p class="noindent">This option has some usage constraints. It: 330 <ul> 331<li>may appear an unlimited number of times. 332</ul> 333 334 <p>Requests from an NTP "client" to a "server" should never be sent 335more rapidly than one every 2 seconds. By default, any IPs returned 336as part of a DNS lookup are assumed to be for a single instance of 337<code>ntpd</code>, and therefore <code>sntp</code> will send queries to these IPs 338one after another, with a 2-second gap in between each query. 339 340 <p>The <span class="option">-c</span> or <span class="option">--concurrent</span> flag says that any IPs 341returned for the DNS lookup of the supplied host-name are on 342different machines, so we can send concurrent queries. 343<div class="node"> 344<p><hr> 345<a name="sntp-gap"></a>Next: <a rel="next" accesskey="n" href="#sntp-kod">sntp kod</a>, 346Previous: <a rel="previous" accesskey="p" href="#sntp-concurrent">sntp concurrent</a>, 347Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 348<br> 349</div> 350 351<h4 class="subsection">gap option (-g)</h4> 352 353<p><a name="index-sntp_002dgap-9"></a> 354This is the “the gap (in milliseconds) between time requests” option. 355This option takes a number argument <span class="file">milliseconds</span>. 356Since we're only going to use the first valid response we get and 357there is benefit to specifying a good number of servers to query, 358separate the queries we send out by the specified number of 359milliseconds. 360<div class="node"> 361<p><hr> 362<a name="sntp-kod"></a>Next: <a rel="next" accesskey="n" href="#sntp-keyfile">sntp keyfile</a>, 363Previous: <a rel="previous" accesskey="p" href="#sntp-gap">sntp gap</a>, 364Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 365<br> 366</div> 367 368<h4 class="subsection">kod option (-K)</h4> 369 370<p><a name="index-sntp_002dkod-10"></a> 371This is the “kod history filename” option. 372This option takes a file argument <span class="file">file-name</span>. 373Specifies the filename to be used for the persistent history of KoD 374responses received from servers. 375<div class="node"> 376<p><hr> 377<a name="sntp-keyfile"></a>Next: <a rel="next" accesskey="n" href="#sntp-logfile">sntp logfile</a>, 378Previous: <a rel="previous" accesskey="p" href="#sntp-kod">sntp kod</a>, 379Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 380<br> 381</div> 382 383<h4 class="subsection">keyfile option (-k)</h4> 384 385<p><a name="index-sntp_002dkeyfile-11"></a> 386This is the “look in this file for the key specified with <span class="option">-a</span>” option. 387This option takes a file argument <span class="file">file-name</span>. 388This option specifies the keyfile. 389<code>sntp</code> will search for the key specified with <span class="option">-a</span> 390<span class="file">keyno</span> in this file. See <span class="command">ntp.keys(5)</span> for more 391information. 392<div class="node"> 393<p><hr> 394<a name="sntp-logfile"></a>Next: <a rel="next" accesskey="n" href="#sntp-steplimit">sntp steplimit</a>, 395Previous: <a rel="previous" accesskey="p" href="#sntp-keyfile">sntp keyfile</a>, 396Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 397<br> 398</div> 399 400<h4 class="subsection">logfile option (-l)</h4> 401 402<p><a name="index-sntp_002dlogfile-12"></a> 403This is the “log to specified logfile” option. 404This option takes a file argument <span class="file">file-name</span>. 405This option causes the client to write log messages to the specified 406<span class="file">logfile</span>. 407<div class="node"> 408<p><hr> 409<a name="sntp-steplimit"></a>Next: <a rel="next" accesskey="n" href="#sntp-ntpversion">sntp ntpversion</a>, 410Previous: <a rel="previous" accesskey="p" href="#sntp-logfile">sntp logfile</a>, 411Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 412<br> 413</div> 414 415<h4 class="subsection">steplimit option (-M)</h4> 416 417<p><a name="index-sntp_002dsteplimit-13"></a> 418This is the “adjustments less than <var>steplimit</var> msec will be slewed” option. 419This option takes a number argument. 420If the time adjustment is less than <span class="file">steplimit</span> milliseconds, 421slew the amount using <span class="command">adjtime(2)</span>. Otherwise, step the 422correction using <span class="command">settimeofday(2)</span>. 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>Next: <a rel="next" accesskey="n" href="#sntp-Notes">sntp Notes</a>, 594Previous: <a rel="previous" accesskey="p" href="#sntp-Usage">sntp Usage</a>, 595Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 596<br> 597</div> 598 599<h4 class="subsection">sntp Authors</h4> 600 601<div class="node"> 602<p><hr> 603<a name="sntp-Notes"></a>Previous: <a rel="previous" accesskey="p" href="#sntp-Authors">sntp Authors</a>, 604Up: <a rel="up" accesskey="u" href="#sntp-Invocation">sntp Invocation</a> 605<br> 606</div> 607 608<h4 class="subsection">sntp Notes</h4> 609 610<div class="node"> 611<p><hr> 612<a name="Usage"></a> 613<br> 614</div> 615 616<!-- node-name, next, previous, up --> 617<h3 class="section">Usage</h3> 618 619<p>The simplest use of this program is as an unprivileged command to 620check the current time, offset, and error in the local clock. 621For example: 622 623<pre class="example"> sntp ntpserver.somewhere 624</pre> 625 <p>With suitable privilege, it can be run as a command or in a 626<code>crom</code> job to reset the local clock from a reliable server, like 627the <code>ntpdate</code> and <code>rdate</code> commands. 628For example: 629 630<pre class="example"> sntp -a ntpserver.somewhere 631</pre> 632 </body></html> 633 634