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