ntp-4.2.8p15.tar.gz: ntp-4.2.8p15/sntp/sntp.1sntpmdoc

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1 .Dd June 23 2020 2 .Dt SNTP 1sntpmdoc User Commands 3 .Os 4 .\" EDIT THIS FILE WITH CAUTION (sntp-opts.mdoc) 5 .\" 6 .\" It has been AutoGen-ed June 23, 2020 at 02:19:35 AM by AutoGen 5.18.5 7 .\" From the definitions sntp-opts.def 8 .\" and the template file agmdoc-cmd.tpl 9 .Sh NAME 10 .Nm sntp 11 .Nd standard Simple Network Time Protocol client program 12 .Sh SYNOPSIS 13 .Nm 14 .\" Mixture of short (flag) options and long options 15 .Op Fl flags 16 .Op Fl flag Op Ar value 17 .Op Fl \-option\-name Ns Oo Oo Ns "=| " Oc Ns Ar value Oc 18 [ hostname\-or\-IP ...] 19 .Pp 20 .Sh DESCRIPTION 21 .Nm 22 can be used as an SNTP client to query a NTP or SNTP server and either display 23 the time or set the local system's time (given suitable privilege). It can be 24 run as an interactive command or from a 25 .Ic cron 26 job. 27 NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol) 28 are defined and described by RFC 5905. 29 .Pp 30 The default is to write the estimated correct local date and time (i.e. not 31 UTC) to the standard output in a format like: 32 .Ic "'1996\-10\-15 20:17:25.123 (+0800) +4.567 +/\- 0.089 [host] IP sN'" 33 where the 34 .Ic "'(+0800)'" 35 means that to get to UTC from the reported local time one must 36 add 8 hours and 0 minutes, 37 the 38 .Ic "'+4.567'" 39 indicates the local clock is 4.567 seconds behind the correct time 40 (so 4.567 seconds must be added to the local clock to get it to be correct). 41 Note that the number of decimals printed for this value will change 42 based on the reported precision of the server. 43 .Ic "'+/\- 0.089'" 44 is the reported 45 .Em synchronization distance 46 (in seconds), which represents the maximum error due to all causes. 47 If the server does not report valid data needed to calculate the 48 synchronization distance, this will be reported as 49 .Ic "'+/\- ?'" . 50 If the 51 .Em host 52 is different from the 53 .Em IP , 54 both will be displayed. 55 Otherwise, only the 56 .Em IP 57 is displayed. 58 Finally, the 59 .Em stratum 60 of the host is reported 61 and the leap indicator is decoded and displayed. 62 .Sh "OPTIONS" 63 .Bl -tag 64 .It Fl 4 , Fl \-ipv4 65 Force IPv4 DNS name resolution. 66 This option must not appear in combination with any of the following options: 67 ipv6. 68 .sp 69 Force DNS resolution of the following host names on the command line 70 to the IPv4 namespace. 71 .It Fl 6 , Fl \-ipv6 72 Force IPv6 DNS name resolution. 73 This option must not appear in combination with any of the following options: 74 ipv4. 75 .sp 76 Force DNS resolution of the following host names on the command line 77 to the IPv6 namespace. 78 .It Fl a Ar auth\-keynumber , Fl \-authentication Ns = Ns Ar auth\-keynumber 79 Enable authentication with the key \fBauth\-keynumber\fP. 80 This option takes an integer number as its argument. 81 .sp 82 Enable authentication using the key specified in this option's 83 argument. The argument of this option is the \fBkeyid\fP, a 84 number specified in the \fBkeyfile\fP as this key's identifier. 85 See the \fBkeyfile\fP option (\fB\-k\fP) for more details. 86 .It Fl b Ar broadcast\-address , Fl \-broadcast Ns = Ns Ar broadcast\-address 87 Listen to the address specified for broadcast time sync. 88 This option may appear an unlimited number of times. 89 .sp 90 If specified \fBsntp\fP will listen to the specified address 91 for NTP broadcasts. The default maximum wait time 92 can (and probably should) be modified with \fB\-t\fP. 93 .It Fl c Ar host\-name , Fl \-concurrent Ns = Ns Ar host\-name 94 Concurrently query all IPs returned for host\-name. 95 This option may appear an unlimited number of times. 96 .sp 97 Requests from an NTP "client" to a "server" should never be sent 98 more rapidly than one every 2 seconds. By default, any IPs returned 99 as part of a DNS lookup are assumed to be for a single instance of 100 \fBntpd\fP, and therefore \fBsntp\fP will send queries to these IPs 101 one after another, with a 2\-second gap in between each query. 102 .sp 103 The \fB\-c\fP or \fB\-\-concurrent\fP flag says that any IPs 104 returned for the DNS lookup of the supplied host\-name are on 105 different machines, so we can send concurrent queries. 106 .It Fl d , Fl \-debug\-level 107 Increase debug verbosity level. 108 This option may appear an unlimited number of times. 109 .sp 110 .It Fl D Ar number , Fl \-set\-debug\-level Ns = Ns Ar number 111 Set the debug verbosity level. 112 This option may appear an unlimited number of times. 113 This option takes an integer number as its argument. 114 .sp 115 .It Fl g Ar milliseconds , Fl \-gap Ns = Ns Ar milliseconds 116 The gap (in milliseconds) between time requests. 117 This option takes an integer number as its argument. 118 The default 119 .Ar milliseconds 120 for this option is: 121 .ti +4 122 50 123 .sp 124 Since we're only going to use the first valid response we get and 125 there is benefit to specifying a good number of servers to query, 126 separate the queries we send out by the specified number of 127 milliseconds. 128 .It Fl K Ar file\-name , Fl \-kod Ns = Ns Ar file\-name 129 KoD history filename. 130 The default 131 .Ar file\-name 132 for this option is: 133 .ti +4 134 /var/db/ntp\-kod 135 .sp 136 Specifies the filename to be used for the persistent history of KoD 137 responses received from servers. If the file does not exist, a 138 warning message will be displayed. The file will not be created. 139 .It Fl k Ar file\-name , Fl \-keyfile Ns = Ns Ar file\-name 140 Look in this file for the key specified with \fB\-a\fP. 141 The default 142 .Ar file\-name 143 for this option is: 144 .ti +4 145 /etc/ntp.keys 146 .sp 147 This option specifies the keyfile. 148 \fBsntp\fP will search for the key specified with \fB\-a\fP 149 \fIkeyno\fP in this file. See \fBntp.keys(5)\fP for more 150 information. 151 .It Fl l Ar file\-name , Fl \-logfile Ns = Ns Ar file\-name 152 Log to specified logfile. 153 .sp 154 This option causes the client to write log messages to the specified 155 \fIlogfile\fP. 156 .It Fl M Ar number , Fl \-steplimit Ns = Ns Ar number 157 Adjustments less than \fBsteplimit\fP msec will be slewed. 158 This option takes an integer number as its argument. 159 The value of 160 .Ar number 161 is constrained to being: 162 .in +4 163 .nf 164 .na 165 greater than or equal to 0 166 .fi 167 .in -4 168 .sp 169 If the time adjustment is less than \fIsteplimit\fP milliseconds, 170 slew the amount using \fBadjtime(2)\fP. Otherwise, step the 171 correction using \fBsettimeofday(2)\fP. The default value is 0, 172 which means all adjustments will be stepped. This is a feature, as 173 different situations demand different values. 174 .It Fl o Ar number , Fl \-ntpversion Ns = Ns Ar number 175 Send \fBint\fP as our NTP protocol version. 176 This option takes an integer number as its argument. 177 The value of 178 .Ar number 179 is constrained to being: 180 .in +4 181 .nf 182 .na 183 in the range 0 through 7 184 .fi 185 .in -4 186 The default 187 .Ar number 188 for this option is: 189 .ti +4 190 4 191 .sp 192 When sending requests to a remote server, tell them we are running 193 NTP protocol version \fIntpversion\fP . 194 .It Fl r , Fl \-usereservedport 195 Use the NTP Reserved Port (port 123). 196 .sp 197 Use port 123, which is reserved for NTP, for our network 198 communications. 199 .It Fl S , Fl \-step 200 OK to 'step' the time with \fBsettimeofday(2)\fP. 201 .sp 202 .It Fl s , Fl \-slew 203 OK to 'slew' the time with \fBadjtime(2)\fP. 204 .sp 205 .It Fl t Ar seconds , Fl \-timeout Ns = Ns Ar seconds 206 The number of seconds to wait for responses. 207 This option takes an integer number as its argument. 208 The default 209 .Ar seconds 210 for this option is: 211 .ti +4 212 5 213 .sp 214 When waiting for a reply, \fBsntp\fP will wait the number 215 of seconds specified before giving up. The default should be 216 more than enough for a unicast response. If \fBsntp\fP is 217 only waiting for a broadcast response a longer timeout is 218 likely needed. 219 .It Fl \-wait , " Fl \-no\-wait" 220 Wait for pending replies (if not setting the time). 221 The \fIno\-wait\fP form will disable the option. 222 This option is enabled by default. 223 .sp 224 If we are not setting the time, wait for all pending responses. 225 .It Fl \&? , Fl \-help 226 Display usage information and exit. 227 .It Fl \&! , Fl \-more\-help 228 Pass the extended usage information through a pager. 229 .It Fl > Oo Ar cfgfile Oc , Fl \-save\-opts Oo Ns = Ns Ar cfgfile Oc 230 Save the option state to \fIcfgfile\fP. The default is the \fIlast\fP 231 configuration file listed in the \fBOPTION PRESETS\fP section, below. 232 The command will exit after updating the config file. 233 .It Fl < Ar cfgfile , Fl \-load\-opts Ns = Ns Ar cfgfile , Fl \-no\-load\-opts 234 Load options from \fIcfgfile\fP. 235 The \fIno\-load\-opts\fP form will disable the loading 236 of earlier config/rc/ini files. \fI\-\-no\-load\-opts\fP is handled early, 237 out of order. 238 .It Fl \-version Op Brq Ar v|c|n 239 Output version of program and exit. The default mode is `v', a simple 240 version. The `c' mode will print copyright information and `n' will 241 print the full copyright notice. 242 .El 243 .Sh "OPTION PRESETS" 244 Any option that is not marked as \fInot presettable\fP may be preset 245 by loading values from configuration ("RC" or ".INI") file(s) and values from 246 environment variables named: 247 .nf 248 \fBSNTP_<option\-name>\fP or \fBSNTP\fP 249 .fi 250 .ad 251 The environmental presets take precedence (are processed later than) 252 the configuration files. 253 The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP". 254 If any of these are directories, then the file \fI.ntprc\fP 255 is searched for within those directories. 256 .Sh USAGE 257 .Bl -tag -width indent 258 .It Li "sntp ntpserver.somewhere" 259 is the simplest use of this program 260 and can be run as an unprivileged command 261 to check the current time and error in the local clock. 262 .It Li "sntp \-Ss \-M 128 ntpserver.somewhere" 263 With suitable privilege, 264 run as a command 265 or from a 266 .Xr cron 8 267 job, 268 .Ic "sntp \-Ss \-M 128 ntpserver.somewhere" 269 will request the time from the server, 270 and if that server reports that it is synchronized 271 then if the offset adjustment is less than 128 milliseconds 272 the correction will be slewed, 273 and if the correction is more than 128 milliseconds 274 the correction will be stepped. 275 .It Li "sntp \-S ntpserver.somewhere" 276 With suitable privilege, 277 run as a command 278 or from a 279 .Xr cron 8 280 job, 281 .Ic "sntp \-S ntpserver.somewhere" 282 will set (step) the local clock from a synchronized specified server, 283 like the (deprecated) 284 .Xr ntpdate 1ntpdatemdoc , 285 or 286 .Xr rdate 8 287 commands. 288 .El 289 .Sh "ENVIRONMENT" 290 See \fBOPTION PRESETS\fP for configuration environment variables. 291 .Sh "FILES" 292 See \fBOPTION PRESETS\fP for configuration files. 293 .Sh "EXIT STATUS" 294 One of the following exit values will be returned: 295 .Bl -tag 296 .It 0 " (EXIT_SUCCESS)" 297 Successful program execution. 298 .It 1 " (EXIT_FAILURE)" 299 The operation failed or the command syntax was not valid. 300 .It 66 " (EX_NOINPUT)" 301 A specified configuration file could not be loaded. 302 .It 70 " (EX_SOFTWARE)" 303 libopts had an internal operational error. Please report 304 it to autogen\-users@lists.sourceforge.net. Thank you. 305 .El 306 .Sh AUTHORS 307 .An "Johannes Maximilian Kuehn" 308 .An "Harlan Stenn" 309 .An "Dave Hart" 310 .Sh "COPYRIGHT" 311 Copyright (C) 1992\-2020 The University of Delaware and Network Time Foundation all rights reserved. 312 This program is released under the terms of the NTP license, <http://ntp.org/license>. 313 .Sh "BUGS" 314 Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org 315 .Sh "NOTES" 316 This manual page was \fIAutoGen\fP\-erated from the \fBsntp\fP 317 option definitions.