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font-family: serif; font-weight: normal; } +--></style> +</head> +<body> +<h1 class="settitle">ntpd: Network Time Protocol (NTP) Daemon User's Manual</h1> +<div class="node"> +<p><hr> +<a name="Top"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Description">ntpd Description</a>, +Previous: <a rel="previous" accesskey="p" href="#dir">(dir)</a>, +Up: <a rel="up" accesskey="u" href="#dir">(dir)</a> +<br> +</div> + +<h2 class="unnumbered">ntpd: Network Time Protocol (NTP) Daemon User Manual</h2> + +<p>The <code>ntpd</code> program is an operating system daemon that synchronizes the +system clock to remote NTP time servers or local reference clocks. +It is a complete implementation of NTP version 4 defined by RFC-5905, but +also retains compatible with version 3 defined by RFC-1305 and versions +1 and 2, defined by RFC-1059 and RFC-1119, respectively. +The program can operate in any of several modes, including client/server, +symmetric and broadcast modes, and with both symmetric-key and public-key +cryptography. + + <p>This document applies to version 4.2.7p482 of <code>ntpd</code>. + +<ul class="menu"> +<li><a accesskey="1" href="#ntpd-Description">ntpd Description</a>: Description +<li><a accesskey="2" href="#ntpd-Invocation">ntpd Invocation</a>: Invoking ntpd +<li><a accesskey="3" href="#Usage">Usage</a>: Usage +</ul> + +<div class="node"> +<p><hr> +<a name="ntpd-Description"></a> +<br> +</div> + +<!-- node-name, next, previous, up --> +<h3 class="section">Description</h3> + +<p>The <code>ntpd</code> program ordinarily requires +a configuration file described at <a href="#ntp_002econf">ntp.conf</a>. +This configuration file contains configuration commands described on +the pages listed above. +However a client can discover remote servers and configure them +automatically. +This makes it possible to deploy a fleet of workstations without +specifying configuration details specific to the local environment. + + <p>The <code>ntpd</code> program normally operates continuously while adjusting the +system time and frequency, but in some cases this might not be +practical. +With the <code>-q</code> option <code>ntpd</code> operates as in continuous mode, but +exits just after setting the clock for the first time. +Most applications will probably want to specify the <code>iburst</code> +option with the <code>server</code> command. +With this option an initial volley of messages is exchanged to +groom the data and set the clock in about ten seconds' time. +If nothing is heard after a few minutes' time, +the daemon times out and exits without setting the clock. + +<div class="node"> +<p><hr> +<a name="ntpd-Invocation"></a> +<br> +</div> + +<h3 class="section">Invoking ntpd</h3> + +<p><a name="index-ntpd-1"></a><a name="index-NTP-daemon-program-2"></a> + + <p>The +<code>ntpd</code> +utility is an operating system daemon which sets +and maintains the system time of day in synchronism with Internet +standard time servers. +It is a complete implementation of the +Network Time Protocol (NTP) version 4, as defined by RFC-5905, +but also retains compatibility with +version 3, as defined by RFC-1305, and versions 1 +and 2, as defined by RFC-1059 and RFC-1119, respectively. + + <p>The +<code>ntpd</code> +utility does most computations in 64-bit floating point +arithmetic and does relatively clumsy 64-bit fixed point operations +only when necessary to preserve the ultimate precision, about 232 +picoseconds. +While the ultimate precision is not achievable with +ordinary workstations and networks of today, it may be required +with future gigahertz CPU clocks and gigabit LANs. + + <p>Ordinarily, +<code>ntpd</code> +reads the +<code>ntp.conf(5)</code> +configuration file at startup time in order to determine the +synchronization sources and operating modes. +It is also possible to +specify a working, although limited, configuration entirely on the +command line, obviating the need for a configuration file. +This may +be particularly useful when the local host is to be configured as a +broadcast/multicast client, with all peers being determined by +listening to broadcasts at run time. + + <p>If NetInfo support is built into +<code>ntpd</code> +then +<code>ntpd</code> +will attempt to read its configuration from the +NetInfo if the default +<code>ntp.conf(5)</code> +file cannot be read and no file is +specified by the +<code>-c</code> +option. + + <p>Various internal +<code>ntpd</code> +variables can be displayed and +configuration options altered while the +<code>ntpd</code> +is running +using the +<code>ntpq(1ntpqmdoc)</code> +and +<code>ntpdc(1ntpdcmdoc)</code> +utility programs. + + <p>When +<code>ntpd</code> +starts it looks at the value of +<code>umask(2)</code>, +and if zero +<code>ntpd</code> +will set the +<code>umask(2)</code> +to 022. + + <p>This section was generated by <strong>AutoGen</strong>, +using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntpd</code> program. +This software is released under the NTP license, <http://ntp.org/license>. + +<ul class="menu"> +<li><a accesskey="1" href="#ntpd-usage">ntpd usage</a>: ntpd help/usage (<span class="option">--help</span>) +<li><a accesskey="2" href="#ntpd-ipv4">ntpd ipv4</a>: ipv4 option (-4) +<li><a accesskey="3" href="#ntpd-ipv6">ntpd ipv6</a>: ipv6 option (-6) +<li><a accesskey="4" href="#ntpd-authreq">ntpd authreq</a>: authreq option (-a) +<li><a accesskey="5" href="#ntpd-authnoreq">ntpd authnoreq</a>: authnoreq option (-A) +<li><a accesskey="6" href="#ntpd-configfile">ntpd configfile</a>: configfile option (-c) +<li><a accesskey="7" href="#ntpd-driftfile">ntpd driftfile</a>: driftfile option (-f) +<li><a accesskey="8" href="#ntpd-panicgate">ntpd panicgate</a>: panicgate option (-g) +<li><a accesskey="9" href="#ntpd-jaildir">ntpd jaildir</a>: jaildir option (-i) +<li><a href="#ntpd-interface">ntpd interface</a>: interface option (-I) +<li><a href="#ntpd-keyfile">ntpd keyfile</a>: keyfile option (-k) +<li><a href="#ntpd-logfile">ntpd logfile</a>: logfile option (-l) +<li><a href="#ntpd-novirtualips">ntpd novirtualips</a>: novirtualips option (-L) +<li><a href="#ntpd-modifymmtimer">ntpd modifymmtimer</a>: modifymmtimer option (-M) +<li><a href="#ntpd-nice">ntpd nice</a>: nice option (-N) +<li><a href="#ntpd-pidfile">ntpd pidfile</a>: pidfile option (-p) +<li><a href="#ntpd-priority">ntpd priority</a>: priority option (-P) +<li><a href="#ntpd-quit">ntpd quit</a>: quit option (-q) +<li><a href="#ntpd-propagationdelay">ntpd propagationdelay</a>: propagationdelay option (-r) +<li><a href="#ntpd-saveconfigquit">ntpd saveconfigquit</a>: saveconfigquit option +<li><a href="#ntpd-statsdir">ntpd statsdir</a>: statsdir option (-s) +<li><a href="#ntpd-trustedkey">ntpd trustedkey</a>: trustedkey option (-t) +<li><a href="#ntpd-user">ntpd user</a>: user option (-u) +<li><a href="#ntpd-updateinterval">ntpd updateinterval</a>: updateinterval option (-U) +<li><a href="#ntpd-wait_002dsync">ntpd wait-sync</a>: wait-sync option (-w) +<li><a href="#ntpd-slew">ntpd slew</a>: slew option (-x) +<li><a href="#ntpd-usepcc">ntpd usepcc</a>: usepcc option +<li><a href="#ntpd-pccfreq">ntpd pccfreq</a>: pccfreq option +<li><a href="#ntpd-mdns">ntpd mdns</a>: mdns option (-m) +<li><a href="#ntpd-config">ntpd config</a>: presetting/configuring ntpd +<li><a href="#ntpd-exit-status">ntpd exit status</a>: exit status +<li><a href="#ntpd-Usage">ntpd Usage</a>: Usage +<li><a href="#ntpd-Files">ntpd Files</a>: Files +<li><a href="#ntpd-See-Also">ntpd See Also</a>: See Also +<li><a href="#ntpd-Bugs">ntpd Bugs</a>: Bugs +<li><a href="#ntpd-Notes">ntpd Notes</a>: Notes +</ul> + +<div class="node"> +<p><hr> +<a name="ntpd-usage"></a>Next: <a rel="next" accesskey="n" href="#ntpd-ipv4">ntpd ipv4</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd help/usage (<span class="option">--help</span>)</h4> + +<p><a name="index-ntpd-help-3"></a> +This is the automatically generated usage text for ntpd. + + <p>The text printed is the same whether selected with the <code>help</code> option +(<span class="option">--help</span>) or the <code>more-help</code> option (<span class="option">--more-help</span>). <code>more-help</code> will print +the usage text by passing it through a pager program. +<code>more-help</code> is disabled on platforms without a working +<code>fork(2)</code> function. The <code>PAGER</code> environment variable is +used to select the program, defaulting to <span class="file">more</span>. Both will exit +with a status code of 0. + +<pre class="example">ntpd - NTP daemon program - Ver. 4.2.7p481 +Usage: ntpd [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \ + [ <server1> ... <serverN> ] + Flg Arg Option-Name Description + -4 no ipv4 Force IPv4 DNS name resolution + - prohibits the option 'ipv6' + -6 no ipv6 Force IPv6 DNS name resolution + - prohibits the option 'ipv4' + -a no authreq Require crypto authentication + - prohibits the option 'authnoreq' + -A no authnoreq Do not require crypto authentication + - prohibits the option 'authreq' + -b no bcastsync Allow us to sync to broadcast servers + -c Str configfile configuration file name + -d no debug-level Increase debug verbosity level + - may appear multiple times + -D Num set-debug-level Set the debug verbosity level + - may appear multiple times + -f Str driftfile frequency drift file name + -g no panicgate Allow the first adjustment to be Big + - may appear multiple times + -i Str jaildir Jail directory + -I Str interface Listen on an interface name or address + - may appear multiple times + -k Str keyfile path to symmetric keys + -l Str logfile path to the log file + -L no novirtualips Do not listen to virtual interfaces + -n no nofork Do not fork + - prohibits the option 'wait-sync' + -N no nice Run at high priority + -p Str pidfile path to the PID file + -P Num priority Process priority + -q no quit Set the time and quit + - prohibits these options: + saveconfigquit + wait-sync + -r Str propagationdelay Broadcast/propagation delay + Str saveconfigquit Save parsed configuration and quit + - prohibits these options: + quit + wait-sync + -s Str statsdir Statistics file location + -t Str trustedkey Trusted key number + - may appear multiple times + -u Str user Run as userid (or userid:groupid) + -U Num updateinterval interval in seconds between scans for new or dropped interfaces + Str var make ARG an ntp variable (RW) + - may appear multiple times + Str dvar make ARG an ntp variable (RW|DEF) + - may appear multiple times + -w Num wait-sync Seconds to wait for first clock sync + - prohibits these options: + nofork + quit + saveconfigquit + -x no slew Slew up to 600 seconds + opt version output version information and exit + -? no help display extended usage information and exit + -! no more-help extended usage information passed thru pager + +Options are specified by doubled hyphens and their name or by a single +hyphen and the flag character. + + +The following option preset mechanisms are supported: + - examining environment variables named NTPD_* + +Please send bug reports to: <http://bugs.ntp.org, bugs@ntp.org> +</pre> + <div class="node"> +<p><hr> +<a name="ntpd-ipv4"></a>Next: <a rel="next" accesskey="n" href="#ntpd-ipv6">ntpd ipv6</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-usage">ntpd usage</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ipv4 option (-4)</h4> + +<p><a name="index-ntpd_002dipv4-4"></a> +This is the “force ipv4 dns name resolution” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must not appear in combination with any of the following options: +ipv6. +</ul> + + <p>Force DNS resolution of following host names on the command line +to the IPv4 namespace. +<div class="node"> +<p><hr> +<a name="ntpd-ipv6"></a>Next: <a rel="next" accesskey="n" href="#ntpd-authreq">ntpd authreq</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-ipv4">ntpd ipv4</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ipv6 option (-6)</h4> + +<p><a name="index-ntpd_002dipv6-5"></a> +This is the “force ipv6 dns name resolution” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must not appear in combination with any of the following options: +ipv4. +</ul> + + <p>Force DNS resolution of following host names on the command line +to the IPv6 namespace. +<div class="node"> +<p><hr> +<a name="ntpd-authreq"></a>Next: <a rel="next" accesskey="n" href="#ntpd-authnoreq">ntpd authnoreq</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-ipv6">ntpd ipv6</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">authreq option (-a)</h4> + +<p><a name="index-ntpd_002dauthreq-6"></a> +This is the “require crypto authentication” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must not appear in combination with any of the following options: +authnoreq. +</ul> + + <p>Require cryptographic authentication for broadcast client, +multicast client and symmetric passive associations. +This is the default. +<div class="node"> +<p><hr> +<a name="ntpd-authnoreq"></a>Next: <a rel="next" accesskey="n" href="#ntpd-configfile">ntpd configfile</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-authreq">ntpd authreq</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">authnoreq option (-A)</h4> + +<p><a name="index-ntpd_002dauthnoreq-7"></a> +This is the “do not require crypto authentication” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must not appear in combination with any of the following options: +authreq. +</ul> + + <p>Do not require cryptographic authentication for broadcast client, +multicast client and symmetric passive associations. +This is almost never a good idea. +<div class="node"> +<p><hr> +<a name="ntpd-configfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-driftfile">ntpd driftfile</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-authnoreq">ntpd authnoreq</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">configfile option (-c)</h4> + +<p><a name="index-ntpd_002dconfigfile-8"></a> +This is the “configuration file name” option. +This option takes a string argument. +The name and path of the configuration file, +<span class="file">/etc/ntp.conf</span> +by default. +<div class="node"> +<p><hr> +<a name="ntpd-driftfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-panicgate">ntpd panicgate</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-configfile">ntpd configfile</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">driftfile option (-f)</h4> + +<p><a name="index-ntpd_002ddriftfile-9"></a> +This is the “frequency drift file name” option. +This option takes a string argument. +The name and path of the frequency file, +<span class="file">/etc/ntp.drift</span> +by default. +This is the same operation as the +<code>driftfile</code> <kbd>driftfile</kbd> +configuration specification in the +<span class="file">/etc/ntp.conf</span> +file. +<div class="node"> +<p><hr> +<a name="ntpd-panicgate"></a>Next: <a rel="next" accesskey="n" href="#ntpd-jaildir">ntpd jaildir</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-driftfile">ntpd driftfile</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">panicgate option (-g)</h4> + +<p><a name="index-ntpd_002dpanicgate-10"></a> +This is the “allow the first adjustment to be big” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>may appear an unlimited number of times. +</ul> + + <p>Normally, +<code>ntpd</code> +exits with a message to the system log if the offset exceeds the panic threshold, which is 1000 s by default. This option allows the time to be set to any value without restriction; however, this can happen only once. If the threshold is exceeded after that, +<code>ntpd</code> +will exit with a message to the system log. This option can be used with the +<code>-q</code> +and +<code>-x</code> +options. +See the +<code>tinker</code> +configuration file directive for other options. +<div class="node"> +<p><hr> +<a name="ntpd-jaildir"></a>Next: <a rel="next" accesskey="n" href="#ntpd-interface">ntpd interface</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-panicgate">ntpd panicgate</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">jaildir option (-i)</h4> + +<p><a name="index-ntpd_002djaildir-11"></a> +This is the “jail directory” option. +This option takes a string argument. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>HAVE_DROPROOT</code> during the compilation. +</ul> + + <p>Chroot the server to the directory +<kbd>jaildir</kbd> +. +This option also implies that the server attempts to drop root privileges at startup. +You may need to also specify a +<code>-u</code> +option. +This option is only available if the OS supports adjusting the clock +without full root privileges. +This option is supported under NetBSD (configure with +<code>--enable-clockctl</code>) or Linux (configure with +<code>--enable-linuxcaps</code>) or Solaris (configure with <code>--enable-solarisprivs</code>). +<div class="node"> +<p><hr> +<a name="ntpd-interface"></a>Next: <a rel="next" accesskey="n" href="#ntpd-keyfile">ntpd keyfile</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-jaildir">ntpd jaildir</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">interface option (-I)</h4> + +<p><a name="index-ntpd_002dinterface-12"></a> +This is the “listen on an interface name or address” option. +This option takes a string argument <span class="file">iface</span>. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>may appear an unlimited number of times. +</ul> + + <p>Open the network address given, or all the addresses associated with the +given interface name. This option may appear multiple times. This option +also implies not opening other addresses, except wildcard and localhost. +This option is deprecated. Please consider using the configuration file +<code>interface</code> command, which is more versatile. +<div class="node"> +<p><hr> +<a name="ntpd-keyfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-logfile">ntpd logfile</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-interface">ntpd interface</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">keyfile option (-k)</h4> + +<p><a name="index-ntpd_002dkeyfile-13"></a> +This is the “path to symmetric keys” option. +This option takes a string argument. +Specify the name and path of the symmetric key file. +<span class="file">/etc/ntp.keys</span> +is the default. +This is the same operation as the +<code>keys</code> <kbd>keyfile</kbd> +configuration file directive. +<div class="node"> +<p><hr> +<a name="ntpd-logfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-novirtualips">ntpd novirtualips</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-keyfile">ntpd keyfile</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">logfile option (-l)</h4> + +<p><a name="index-ntpd_002dlogfile-14"></a> +This is the “path to the log file” option. +This option takes a string argument. +Specify the name and path of the log file. +The default is the system log file. +This is the same operation as the +<code>logfile</code> <kbd>logfile</kbd> +configuration file directive. +<div class="node"> +<p><hr> +<a name="ntpd-novirtualips"></a>Next: <a rel="next" accesskey="n" href="#ntpd-modifymmtimer">ntpd modifymmtimer</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-logfile">ntpd logfile</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">novirtualips option (-L)</h4> + +<p><a name="index-ntpd_002dnovirtualips-15"></a> +This is the “do not listen to virtual interfaces” option. +Do not listen to virtual interfaces, defined as those with +names containing a colon. This option is deprecated. Please +consider using the configuration file <code>interface</code> command, which +is more versatile. +<div class="node"> +<p><hr> +<a name="ntpd-modifymmtimer"></a>Next: <a rel="next" accesskey="n" href="#ntpd-nice">ntpd nice</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-novirtualips">ntpd novirtualips</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">modifymmtimer option (-M)</h4> + +<p><a name="index-ntpd_002dmodifymmtimer-16"></a> +This is the “modify multimedia timer (windows only)” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>SYS_WINNT</code> during the compilation. +</ul> + + <p>Set the Windows Multimedia Timer to highest resolution. This +ensures the resolution does not change while ntpd is running, +avoiding timekeeping glitches associated with changes. +<div class="node"> +<p><hr> +<a name="ntpd-nice"></a>Next: <a rel="next" accesskey="n" href="#ntpd-pidfile">ntpd pidfile</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-modifymmtimer">ntpd modifymmtimer</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">nice option (-N)</h4> + +<p><a name="index-ntpd_002dnice-17"></a> +This is the “run at high priority” option. +To the extent permitted by the operating system, run +<code>ntpd</code> +at the highest priority. +<div class="node"> +<p><hr> +<a name="ntpd-pidfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-priority">ntpd priority</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-nice">ntpd nice</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">pidfile option (-p)</h4> + +<p><a name="index-ntpd_002dpidfile-18"></a> +This is the “path to the pid file” option. +This option takes a string argument. +Specify the name and path of the file used to record +<code>ntpd</code>'s +process ID. +This is the same operation as the +<code>pidfile</code> <kbd>pidfile</kbd> +configuration file directive. +<div class="node"> +<p><hr> +<a name="ntpd-priority"></a>Next: <a rel="next" accesskey="n" href="#ntpd-quit">ntpd quit</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-pidfile">ntpd pidfile</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">priority option (-P)</h4> + +<p><a name="index-ntpd_002dpriority-19"></a> +This is the “process priority” option. +This option takes a number argument. +To the extent permitted by the operating system, run +<code>ntpd</code> +at the specified +<code>sched_setscheduler(SCHED_FIFO)</code> +priority. +<div class="node"> +<p><hr> +<a name="ntpd-quit"></a>Next: <a rel="next" accesskey="n" href="#ntpd-propagationdelay">ntpd propagationdelay</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-priority">ntpd priority</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">quit option (-q)</h4> + +<p><a name="index-ntpd_002dquit-20"></a> +This is the “set the time and quit” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must not appear in combination with any of the following options: +saveconfigquit, wait-sync. +</ul> + + <p><code>ntpd</code> +will not daemonize and will exit after the clock is first +synchronized. This behavior mimics that of the +<code>ntpdate</code> +program, which will soon be replaced with a shell script. +The +<code>-g</code> +and +<code>-x</code> +options can be used with this option. +Note: The kernel time discipline is disabled with this option. +<div class="node"> +<p><hr> +<a name="ntpd-propagationdelay"></a>Next: <a rel="next" accesskey="n" href="#ntpd-saveconfigquit">ntpd saveconfigquit</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-quit">ntpd quit</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">propagationdelay option (-r)</h4> + +<p><a name="index-ntpd_002dpropagationdelay-21"></a> +This is the “broadcast/propagation delay” option. +This option takes a string argument. +Specify the default propagation delay from the broadcast/multicast server to this client. This is necessary only if the delay cannot be computed automatically by the protocol. +<div class="node"> +<p><hr> +<a name="ntpd-saveconfigquit"></a>Next: <a rel="next" accesskey="n" href="#ntpd-statsdir">ntpd statsdir</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-propagationdelay">ntpd propagationdelay</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">saveconfigquit option</h4> + +<p><a name="index-ntpd_002dsaveconfigquit-22"></a> +This is the “save parsed configuration and quit” option. +This option takes a string argument. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>SAVECONFIG</code> during the compilation. +<li>must not appear in combination with any of the following options: +quit, wait-sync. +</ul> + + <p>Cause <code>ntpd</code> to parse its startup configuration file and save an +equivalent to the given filename and exit. This option was +designed for automated testing. +<div class="node"> +<p><hr> +<a name="ntpd-statsdir"></a>Next: <a rel="next" accesskey="n" href="#ntpd-trustedkey">ntpd trustedkey</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-saveconfigquit">ntpd saveconfigquit</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">statsdir option (-s)</h4> + +<p><a name="index-ntpd_002dstatsdir-23"></a> +This is the “statistics file location” option. +This option takes a string argument. +Specify the directory path for files created by the statistics facility. +This is the same operation as the +<code>statsdir</code> <kbd>statsdir</kbd> +configuration file directive. +<div class="node"> +<p><hr> +<a name="ntpd-trustedkey"></a>Next: <a rel="next" accesskey="n" href="#ntpd-user">ntpd user</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-statsdir">ntpd statsdir</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">trustedkey option (-t)</h4> + +<p><a name="index-ntpd_002dtrustedkey-24"></a> +This is the “trusted key number” option. +This option takes a string argument <span class="file">tkey</span>. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>may appear an unlimited number of times. +</ul> + + <p>Add the specified key number to the trusted key list. +<div class="node"> +<p><hr> +<a name="ntpd-user"></a>Next: <a rel="next" accesskey="n" href="#ntpd-updateinterval">ntpd updateinterval</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-trustedkey">ntpd trustedkey</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">user option (-u)</h4> + +<p><a name="index-ntpd_002duser-25"></a> +This is the “run as userid (or userid:groupid)” option. +This option takes a string argument. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>HAVE_DROPROOT</code> during the compilation. +</ul> + + <p>Specify a user, and optionally a group, to switch to. +This option is only available if the OS supports adjusting the clock +without full root privileges. +This option is supported under NetBSD (configure with +<code>--enable-clockctl</code>) or Linux (configure with +<code>--enable-linuxcaps</code>) or Solaris (configure with <code>--enable-solarisprivs</code>). +<div class="node"> +<p><hr> +<a name="ntpd-updateinterval"></a>Next: <a rel="next" accesskey="n" href="#ntpd-wait_002dsync">ntpd wait-sync</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-user">ntpd user</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">updateinterval option (-U)</h4> + +<p><a name="index-ntpd_002dupdateinterval-26"></a> +This is the “interval in seconds between scans for new or dropped interfaces” option. +This option takes a number argument. +Give the time in seconds between two scans for new or dropped interfaces. +For systems with routing socket support the scans will be performed shortly after the interface change +has been detected by the system. +Use 0 to disable scanning. 60 seconds is the minimum time between scans. +<div class="node"> +<p><hr> +<a name="ntpd-wait_002dsync"></a>Next: <a rel="next" accesskey="n" href="#ntpd-slew">ntpd slew</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-updateinterval">ntpd updateinterval</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">wait-sync option (-w)</h4> + +<p><a name="index-ntpd_002dwait_002dsync-27"></a> +This is the “seconds to wait for first clock sync” option. +This option takes a number argument. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>HAVE_WORKING_FORK</code> during the compilation. +<li>must not appear in combination with any of the following options: +nofork, quit, saveconfigquit. +</ul> + + <p>If greater than zero, alters <code>ntpd</code>'s behavior when forking to +daemonize. Instead of exiting with status 0 immediately after +the fork, the parent waits up to the specified number of +seconds for the child to first synchronize the clock. The exit +status is zero (success) if the clock was synchronized, +otherwise it is <code>ETIMEDOUT</code>. +This provides the option for a script starting <code>ntpd</code> to easily +wait for the first set of the clock before proceeding. +<div class="node"> +<p><hr> +<a name="ntpd-slew"></a>Next: <a rel="next" accesskey="n" href="#ntpd-usepcc">ntpd usepcc</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-wait_002dsync">ntpd wait-sync</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">slew option (-x)</h4> + +<p><a name="index-ntpd_002dslew-28"></a> +This is the “slew up to 600 seconds” option. +Normally, the time is slewed if the offset is less than the step threshold, which is 128 ms by default, and stepped if above the threshold. +This option sets the threshold to 600 s, which is well within the accuracy window to set the clock manually. +Note: Since the slew rate of typical Unix kernels is limited to 0.5 ms/s, each second of adjustment requires an amortization interval of 2000 s. +Thus, an adjustment as much as 600 s will take almost 14 days to complete. +This option can be used with the +<code>-g</code> +and +<code>-q</code> +options. +See the +<code>tinker</code> +configuration file directive for other options. +Note: The kernel time discipline is disabled with this option. +<div class="node"> +<p><hr> +<a name="ntpd-usepcc"></a>Next: <a rel="next" accesskey="n" href="#ntpd-pccfreq">ntpd pccfreq</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-slew">ntpd slew</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">usepcc option</h4> + +<p><a name="index-ntpd_002dusepcc-29"></a> +This is the “use cpu cycle counter (windows only)” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>SYS_WINNT</code> during the compilation. +</ul> + + <p>Attempt to substitute the CPU counter for <code>QueryPerformanceCounter</code>. +The CPU counter and <code>QueryPerformanceCounter</code> are compared, and if +they have the same frequency, the CPU counter (RDTSC on x86) is +used directly, saving the overhead of a system call. +<div class="node"> +<p><hr> +<a name="ntpd-pccfreq"></a>Next: <a rel="next" accesskey="n" href="#ntpd-mdns">ntpd mdns</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-usepcc">ntpd usepcc</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">pccfreq option</h4> + +<p><a name="index-ntpd_002dpccfreq-30"></a> +This is the “force cpu cycle counter use (windows only)” option. +This option takes a string argument. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>SYS_WINNT</code> during the compilation. +</ul> + + <p>Force substitution the CPU counter for <code>QueryPerformanceCounter</code>. +The CPU counter (RDTSC on x86) is used unconditionally with the +given frequency (in Hz). +<div class="node"> +<p><hr> +<a name="ntpd-mdns"></a>Next: <a rel="next" accesskey="n" href="#ntpd-config">ntpd config</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-pccfreq">ntpd pccfreq</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">mdns option (-m)</h4> + +<p><a name="index-ntpd_002dmdns-31"></a> +This is the “register with mdns as a ntp server” option. + +<p class="noindent">This option has some usage constraints. It: + <ul> +<li>must be compiled in by defining <code>HAVE_DNSREGISTRATION</code> during the compilation. +</ul> + + <p>Registers as an NTP server with the local mDNS server which allows +the server to be discovered via mDNS client lookup. + +<div class="node"> +<p><hr> +<a name="ntpd-config"></a>Next: <a rel="next" accesskey="n" href="#ntpd-exit-status">ntpd exit status</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-mdns">ntpd mdns</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">presetting/configuring ntpd</h4> + +<p>Any option that is not marked as <i>not presettable</i> may be preset by +loading values from environment variables named <code>NTPD</code> and <code>NTPD_<OPTION_NAME></code>. <code><OPTION_NAME></code> must be one of +the options listed above in upper case and segmented with underscores. +The <code>NTPD</code> variable will be tokenized and parsed like +the command line. The remaining variables are tested for existence and their +values are treated like option arguments. + + <p>The command line options relating to configuration and/or usage help are: + +<h5 class="subsubheading">version (-)</h5> + +<p>Print the program version to standard out, optionally with licensing +information, then exit 0. The optional argument specifies how much licensing +detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument. +Only the first letter of the argument is examined: + + <dl> +<dt><span class="samp">version</span><dd>Only print the version. This is the default. +<br><dt><span class="samp">copyright</span><dd>Name the copyright usage licensing terms. +<br><dt><span class="samp">verbose</span><dd>Print the full copyright usage licensing terms. +</dl> + +<div class="node"> +<p><hr> +<a name="ntpd-exit-status"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Usage">ntpd Usage</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-config">ntpd config</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd exit status</h4> + +<p>One of the following exit values will be returned: + <dl> +<dt><span class="samp">0 (EXIT_SUCCESS)</span><dd>Successful program execution. +<br><dt><span class="samp">1 (EXIT_FAILURE)</span><dd>The operation failed or the command syntax was not valid. +</dl> + <div class="node"> +<p><hr> +<a name="ntpd-Usage"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Files">ntpd Files</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-exit-status">ntpd exit status</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd Usage</h4> + +<div class="node"> +<p><hr> +<a name="ntpd-Files"></a>Next: <a rel="next" accesskey="n" href="#ntpd-See-Also">ntpd See Also</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-Usage">ntpd Usage</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd Files</h4> + +<div class="node"> +<p><hr> +<a name="ntpd-See-Also"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Bugs">ntpd Bugs</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-Files">ntpd Files</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd See Also</h4> + +<div class="node"> +<p><hr> +<a name="ntpd-Bugs"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Notes">ntpd Notes</a>, +Previous: <a rel="previous" accesskey="p" href="#ntpd-See-Also">ntpd See Also</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd Bugs</h4> + +<div class="node"> +<p><hr> +<a name="ntpd-Notes"></a>Previous: <a rel="previous" accesskey="p" href="#ntpd-Bugs">ntpd Bugs</a>, +Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> +<br> +</div> + +<h4 class="subsection">ntpd Notes</h4> + +<div class="node"> +<p><hr> +<a name="Usage"></a> +<br> +</div> + +<!-- node-name, next, previous, up --> +<h3 class="section">Usage</h3> + |