ntp-wait.html revision 1.1.1.14
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accesskey="u" rel="up">(dir)</a> </p> 57</div> 58<h1 class="node-heading">Top</h1> 59 60<p>This document describes the use of the NTP Project’s <code>ntp-wait</code> program. 61</p> 62<p>If there are time-sensitive applications, 63the proper sequence of events is to 64run <code>ntpd -g</code> as early as possible, 65then invoke all of the non-time-sensitive process, 66run <code>ntp-wait</code> to block 67until the system’s time has stabilized and synchronized, 68and only then start any applicaitons (like database servers) that require 69accurate and stable time. 70</p> 71<p>This document applies to version 4.2.8p15 of <code>ntp-wait</code>. 72</p> 73<a name="SEC_Overview"></a> 74<h2 class="shortcontents-heading">Short Table of Contents</h2> 75 76<div class="shortcontents"> 77<li><a name="stoc-Invoking-ntp_002dwait" href="#toc-Invoking-ntp_002dwait">1 Invoking ntp-wait</a></li> 78 79</div> 80 81 82<table class="menu" border="0" cellspacing="0"> 83<tr><td align="left" valign="top">• ntp-wait Description:</td><td> </td><td align="left" valign="top">Description 84</td></tr> 85<tr><td align="left" valign="top">• <a href="#ntp_002dwait-Invocation" accesskey="2">ntp-wait Invocation</a>:</td><td> </td><td align="left" valign="top">Invoking ntp-wait 86</td></tr> 87</table> 88 89<hr> 90<a name="ntp_002dwait-Invocation"></a> 91<div class="header"> 92<p> 93Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p> 94</div> 95<a name="Invoking-ntp_002dwait"></a> 96<h3 class="section">1 Invoking ntp-wait</h3> 97<a name="index-ntp_002dwait"></a> 98<a name="index-Wait-for-ntpd-to-stabilize-the-system-clock"></a> 99 100 101 102<p><code>ntp-wait</code> 103will send at most 104<kbd>num-tries</kbd> 105queries to 106<code>ntpd(8)</code>, 107sleeping for 108<kbd>secs-between-tries</kbd> 109after each status return that says 110<code>ntpd(8)</code> 111has not yet produced a synchronized and stable system clock. 112</p> 113<p><code>ntp-wait</code> 114will do this quietly, unless the 115<code>-v</code> 116flag is provided. 117This can be useful at boot time, to delay the boot sequence until after 118<kbd>ntpd</kbd> <kbd>-g</kbd> 119has set the time. 120</p> 121<p>This section was generated by <strong>AutoGen</strong>, 122using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntp-wait</code> program. 123</p> 124<table class="menu" border="0" cellspacing="0"> 125<tr><td align="left" valign="top">• <a href="#ntp_002dwait-usage" accesskey="1">ntp-wait usage</a>:</td><td> </td><td align="left" valign="top">ntp-wait help/usage (<samp>--help</samp>) 126</td></tr> 127<tr><td align="left" valign="top">• <a href="#ntp_002dwait-tries" accesskey="2">ntp-wait tries</a>:</td><td> </td><td align="left" valign="top">tries option (-n) 128</td></tr> 129<tr><td align="left" valign="top">• <a href="#ntp_002dwait-sleep" accesskey="3">ntp-wait sleep</a>:</td><td> </td><td align="left" valign="top">sleep option (-s) 130</td></tr> 131<tr><td align="left" valign="top">• <a href="#ntp_002dwait-verbose" accesskey="4">ntp-wait verbose</a>:</td><td> </td><td align="left" valign="top">verbose option (-v) 132</td></tr> 133<tr><td align="left" valign="top">• <a href="#ntp_002dwait-exit-status" accesskey="5">ntp-wait exit status</a>:</td><td> </td><td align="left" valign="top">exit status 134</td></tr> 135<tr><td align="left" valign="top">• <a href="#ntp_002dwait-Authors" accesskey="6">ntp-wait Authors</a>:</td><td> </td><td align="left" valign="top">Authors 136</td></tr> 137<tr><td align="left" valign="top">• <a href="#ntp_002dwait-Notes" accesskey="7">ntp-wait Notes</a>:</td><td> </td><td align="left" valign="top">Notes 138</td></tr> 139</table> 140 141<hr> 142<a name="ntp_002dwait-usage"></a> 143<div class="header"> 144<p> 145Next: <a href="#ntp_002dwait-tries" accesskey="n" rel="next">ntp-wait tries</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 146</div> 147<a name="ntp_002dwait-help_002fusage-_0028_002d_002dhelp_0029"></a> 148<h4 class="subsection">1.1 ntp-wait help/usage (<samp>--help</samp>)</h4> 149<a name="index-ntp_002dwait-help"></a> 150 151<p>This is the automatically generated usage text for ntp-wait. 152</p> 153<p>The text printed is the same whether selected with the <code>help</code> option 154(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>). <code>more-help</code> will print 155the usage text by passing it through a pager program. 156<code>more-help</code> is disabled on platforms without a working 157<code>fork(2)</code> function. The <code>PAGER</code> environment variable is 158used to select the program, defaulting to <samp>more</samp>. Both will exit 159with a status code of 0. 160</p> 161<div class="example"> 162<pre class="example">ntp-wait - Wait for ntpd to stabilize the system clock - Ver. 4.2.8p15 163USAGE: ntp-wait [ -<flag> [<val>] | --<name>[{=| }<val>] ]... 164 165 -n, --tries=num Number of times to check ntpd 166 -s, --sleep=num How long to sleep between tries 167 -v, --verbose Be verbose 168 -?, --help Display usage information and exit 169 --more-help Pass the extended usage text through a pager 170 171Options are specified by doubled hyphens and their name or by a single 172hyphen and the flag character. 173</pre></div> 174 175<hr> 176<a name="ntp_002dwait-tries"></a> 177<div class="header"> 178<p> 179Next: <a href="#ntp_002dwait-sleep" accesskey="n" rel="next">ntp-wait sleep</a>, Previous: <a href="#ntp_002dwait-usage" accesskey="p" rel="prev">ntp-wait usage</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 180</div> 181<a name="tries-option-_0028_002dn_0029"></a> 182<h4 class="subsection">1.2 tries option (-n)</h4> 183<a name="index-ntp_002dwait_002dtries"></a> 184 185<p>This is the “number of times to check ntpd” option. 186This option takes a number argument. 187 The maximum number of times we will check <code>ntpd</code> to see if 188 it has been able to synchronize and stabilize the system clock. 189</p><hr> 190<a name="ntp_002dwait-sleep"></a> 191<div class="header"> 192<p> 193Next: <a href="#ntp_002dwait-verbose" accesskey="n" rel="next">ntp-wait verbose</a>, Previous: <a href="#ntp_002dwait-tries" accesskey="p" rel="prev">ntp-wait tries</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 194</div> 195<a name="sleep-option-_0028_002ds_0029"></a> 196<h4 class="subsection">1.3 sleep option (-s)</h4> 197<a name="index-ntp_002dwait_002dsleep"></a> 198 199<p>This is the “how long to sleep between tries” option. 200This option takes a number argument <samp>secs-between-tries</samp>. 201 We will sleep for <samp>secs-between-tries</samp> after each query 202 of <code>ntpd</code> that returns "the time is not yet stable". 203</p><hr> 204<a name="ntp_002dwait-verbose"></a> 205<div class="header"> 206<p> 207Next: <a href="#ntp_002dwait-exit-status" accesskey="n" rel="next">ntp-wait exit status</a>, Previous: <a href="#ntp_002dwait-sleep" accesskey="p" rel="prev">ntp-wait sleep</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 208</div> 209<a name="verbose-option-_0028_002dv_0029"></a> 210<h4 class="subsection">1.4 verbose option (-v)</h4> 211<a name="index-ntp_002dwait_002dverbose"></a> 212 213<p>This is the “be verbose” option. 214 By default, <code>ntp-wait</code> is silent. 215 With this option, <code>ntp-wait</code> will provide status information. 216</p><hr> 217<a name="ntp_002dwait-exit-status"></a> 218<div class="header"> 219<p> 220Next: <a href="#ntp_002dwait-Authors" accesskey="n" rel="next">ntp-wait Authors</a>, Previous: <a href="#ntp_002dwait-verbose" accesskey="p" rel="prev">ntp-wait verbose</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 221</div> 222<a name="ntp_002dwait-exit-status-1"></a> 223<h4 class="subsection">1.5 ntp-wait exit status</h4> 224 225<p>One of the following exit values will be returned: 226</p><dl compact="compact"> 227<dt>‘<samp>0 (EXIT_SUCCESS)</samp>’</dt> 228<dd><p>Successful program execution. 229</p></dd> 230<dt>‘<samp>1 (EXIT_FAILURE)</samp>’</dt> 231<dd><p>The operation failed or the command syntax was not valid. 232</p></dd> 233</dl> 234<hr> 235<a name="ntp_002dwait-Authors"></a> 236<div class="header"> 237<p> 238Next: <a href="#ntp_002dwait-Notes" accesskey="n" rel="next">ntp-wait Notes</a>, Previous: <a href="#ntp_002dwait-exit-status" accesskey="p" rel="prev">ntp-wait exit status</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 239</div> 240<a name="ntp_002dwait-Authors-1"></a> 241<h4 class="subsection">1.6 ntp-wait Authors</h4> 242<hr> 243<a name="ntp_002dwait-Notes"></a> 244<div class="header"> 245<p> 246Previous: <a href="#ntp_002dwait-Authors" accesskey="p" rel="prev">ntp-wait Authors</a>, Up: <a href="#ntp_002dwait-Invocation" accesskey="u" rel="up">ntp-wait Invocation</a> </p> 247</div> 248<a name="ntp_002dwait-Notes-1"></a> 249<h4 class="subsection">1.7 ntp-wait Notes</h4> 250<hr> 251 252 253 254</body> 255</html> 256