363 lines
12 KiB
Groff
363 lines
12 KiB
Groff
.de1 NOP
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. it 1 an-trap
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. if \\n[.$] \,\\$*\/
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..
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.el \
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.TH sntp @SNTP_MS@ "14 Aug 2018" "4.2.8p12" "User Commands"
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.\"
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.\" EDIT THIS FILE WITH CAUTION (/tmp/.ag-7ray4x/ag-hsaq3x)
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.\"
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.\" It has been AutoGen-ed August 14, 2018 at 08:27:33 AM by AutoGen 5.18.5
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.\" From the definitions sntp-opts.def
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.\" and the template file agman-cmd.tpl
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.SH NAME
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\f\*[B-Font]sntp\fP
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\- standard Simple Network Time Protocol client program
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.SH SYNOPSIS
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\f\*[B-Font]sntp\fP
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.\" Mixture of short (flag) options and long options
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[\f\*[B-Font]\-flags\f[]]
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[\f\*[B-Font]\-flag\f[] [\f\*[I-Font]value\f[]]]
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[\f\*[B-Font]\-\-option-name\f[][[=| ]\f\*[I-Font]value\f[]]]
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[ hostname-or-IP ...]
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.sp \n(Ppu
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.ne 2
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.SH DESCRIPTION
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\f\*[B-Font]sntp\fP
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can be used as an SNTP client to query a NTP or SNTP server and either display
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the time or set the local system's time (given suitable privilege). It can be
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run as an interactive command or from a
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\f\*[B-Font]cron\f[]
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job.
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NTP (the Network Time Protocol) and SNTP (the Simple Network Time Protocol)
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are defined and described by RFC 5905.
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.sp \n(Ppu
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.ne 2
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The default is to write the estimated correct local date and time (i.e. not
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UTC) to the standard output in a format like:
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\f\*[B-Font]'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN'\f[]
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where the
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\f\*[B-Font]'(+0800)'\f[]
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means that to get to UTC from the reported local time one must
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add 8 hours and 0 minutes,
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the
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\f\*[B-Font]'+4.567'\f[]
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indicates the local clock is 4.567 seconds behind the correct time
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(so 4.567 seconds must be added to the local clock to get it to be correct).
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Note that the number of decimals printed for this value will change
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based on the reported precision of the server.
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\f\*[B-Font]'+/- 0.089'\f[]
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is the reported
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\fIsynchronization\f[] \fIdistance\f[]
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(in seconds), which represents the maximum error due to all causes.
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If the server does not report valid data needed to calculate the
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synchronization distance, this will be reported as
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\f\*[B-Font]'+/- ?'\f[].
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If the
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\fIhost\f[]
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is different from the
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\fIIP\f[],
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both will be displayed.
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Otherwise, only the
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\fIIP\f[]
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is displayed.
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Finally, the
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\fIstratum\f[]
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of the host is reported
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and the leap indicator is decoded and displayed.
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.SH "OPTIONS"
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.TP
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.NOP \f\*[B-Font]\-4\f[], \f\*[B-Font]\-\-ipv4\f[]
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Force IPv4 DNS name resolution.
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This option must not appear in combination with any of the following options:
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ipv6.
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.sp
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Force DNS resolution of the following host names on the command line
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to the IPv4 namespace.
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.TP
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.NOP \f\*[B-Font]\-6\f[], \f\*[B-Font]\-\-ipv6\f[]
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Force IPv6 DNS name resolution.
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This option must not appear in combination with any of the following options:
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ipv4.
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.sp
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Force DNS resolution of the following host names on the command line
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to the IPv6 namespace.
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.TP
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.NOP \f\*[B-Font]\-a\f[] \f\*[I-Font]auth\-keynumber\f[], \f\*[B-Font]\-\-authentication\f[]=\f\*[I-Font]auth\-keynumber\f[]
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Enable authentication with the key \fBauth-keynumber\fP.
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This option takes an integer number as its argument.
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.sp
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Enable authentication using the key specified in this option's
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argument. The argument of this option is the \fBkeyid\fP, a
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number specified in the \fBkeyfile\fP as this key's identifier.
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See the \fBkeyfile\fP option (\fB-k\fP) for more details.
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.TP
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.NOP \f\*[B-Font]\-b\f[] \f\*[I-Font]broadcast\-address\f[], \f\*[B-Font]\-\-broadcast\f[]=\f\*[I-Font]broadcast\-address\f[]
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Listen to the address specified for broadcast time sync.
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This option may appear an unlimited number of times.
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.sp
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If specified \fBsntp\fP will listen to the specified address
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for NTP broadcasts. The default maximum wait time
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can (and probably should) be modified with \fB-t\fP.
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.TP
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.NOP \f\*[B-Font]\-c\f[] \f\*[I-Font]host\-name\f[], \f\*[B-Font]\-\-concurrent\f[]=\f\*[I-Font]host\-name\f[]
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Concurrently query all IPs returned for host-name.
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This option may appear an unlimited number of times.
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.sp
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Requests from an NTP "client" to a "server" should never be sent
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more rapidly than one every 2 seconds. By default, any IPs returned
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as part of a DNS lookup are assumed to be for a single instance of
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\fBntpd\fP, and therefore \fBsntp\fP will send queries to these IPs
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one after another, with a 2-second gap in between each query.
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.sp
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The \fB-c\fP or \fB--concurrent\fP flag says that any IPs
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returned for the DNS lookup of the supplied host-name are on
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different machines, so we can send concurrent queries.
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.TP
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.NOP \f\*[B-Font]\-d\f[], \f\*[B-Font]\-\-debug\-level\f[]
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Increase debug verbosity level.
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This option may appear an unlimited number of times.
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.sp
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.TP
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.NOP \f\*[B-Font]\-D\f[] \f\*[I-Font]number\f[], \f\*[B-Font]\-\-set\-debug\-level\f[]=\f\*[I-Font]number\f[]
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Set the debug verbosity level.
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This option may appear an unlimited number of times.
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This option takes an integer number as its argument.
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.sp
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.TP
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.NOP \f\*[B-Font]\-g\f[] \f\*[I-Font]milliseconds\f[], \f\*[B-Font]\-\-gap\f[]=\f\*[I-Font]milliseconds\f[]
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The gap (in milliseconds) between time requests.
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This option takes an integer number as its argument.
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The default
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\f\*[I-Font]milliseconds\f[]
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for this option is:
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.ti +4
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50
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.sp
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Since we're only going to use the first valid response we get and
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there is benefit to specifying a good number of servers to query,
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separate the queries we send out by the specified number of
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milliseconds.
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.TP
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.NOP \f\*[B-Font]\-K\f[] \f\*[I-Font]file\-name\f[], \f\*[B-Font]\-\-kod\f[]=\f\*[I-Font]file\-name\f[]
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KoD history filename.
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The default
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\f\*[I-Font]file\-name\f[]
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for this option is:
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.ti +4
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/var/db/ntp-kod
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.sp
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Specifies the filename to be used for the persistent history of KoD
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responses received from servers. If the file does not exist, a
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warning message will be displayed. The file will not be created.
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.TP
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.NOP \f\*[B-Font]\-k\f[] \f\*[I-Font]file\-name\f[], \f\*[B-Font]\-\-keyfile\f[]=\f\*[I-Font]file\-name\f[]
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Look in this file for the key specified with \fB-a\fP.
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The default
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\f\*[I-Font]file\-name\f[]
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for this option is:
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.ti +4
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/etc/ntp.keys
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.sp
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This option specifies the keyfile.
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\fBsntp\fP will search for the key specified with \fB-a\fP
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\fIkeyno\fP in this file. See \fBntp.keys(5)\fP for more
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information.
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.TP
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.NOP \f\*[B-Font]\-l\f[] \f\*[I-Font]file\-name\f[], \f\*[B-Font]\-\-logfile\f[]=\f\*[I-Font]file\-name\f[]
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Log to specified logfile.
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.sp
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This option causes the client to write log messages to the specified
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\fIlogfile\fP.
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.TP
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.NOP \f\*[B-Font]\-M\f[] \f\*[I-Font]number\f[], \f\*[B-Font]\-\-steplimit\f[]=\f\*[I-Font]number\f[]
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Adjustments less than \fBsteplimit\fP msec will be slewed.
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This option takes an integer number as its argument.
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The value of
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\f\*[I-Font]number\f[]
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is constrained to being:
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.in +4
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.nf
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.na
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greater than or equal to 0
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.fi
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.in -4
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.sp
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If the time adjustment is less than \fIsteplimit\fP milliseconds,
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slew the amount using \fBadjtime(2)\fP. Otherwise, step the
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correction using \fBsettimeofday(2)\fP. The default value is 0,
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which means all adjustments will be stepped. This is a feature, as
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different situations demand different values.
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.TP
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.NOP \f\*[B-Font]\-o\f[] \f\*[I-Font]number\f[], \f\*[B-Font]\-\-ntpversion\f[]=\f\*[I-Font]number\f[]
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Send \fBint\fP as our NTP protocol version.
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This option takes an integer number as its argument.
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The value of
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\f\*[I-Font]number\f[]
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is constrained to being:
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.in +4
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.nf
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.na
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in the range 0 through 7
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.fi
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.in -4
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The default
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\f\*[I-Font]number\f[]
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for this option is:
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.ti +4
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4
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.sp
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When sending requests to a remote server, tell them we are running
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NTP protocol version \fIntpversion\fP .
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.TP
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.NOP \f\*[B-Font]\-r\f[], \f\*[B-Font]\-\-usereservedport\f[]
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Use the NTP Reserved Port (port 123).
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.sp
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Use port 123, which is reserved for NTP, for our network
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communications.
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.TP
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.NOP \f\*[B-Font]\-S\f[], \f\*[B-Font]\-\-step\f[]
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OK to 'step' the time with \fBsettimeofday(2)\fP.
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.sp
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.TP
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.NOP \f\*[B-Font]\-s\f[], \f\*[B-Font]\-\-slew\f[]
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OK to 'slew' the time with \fBadjtime(2)\fP.
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.sp
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.TP
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.NOP \f\*[B-Font]\-t\f[] \f\*[I-Font]seconds\f[], \f\*[B-Font]\-\-timeout\f[]=\f\*[I-Font]seconds\f[]
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The number of seconds to wait for responses.
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This option takes an integer number as its argument.
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The default
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\f\*[I-Font]seconds\f[]
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for this option is:
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.ti +4
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5
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.sp
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When waiting for a reply, \fBsntp\fP will wait the number
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of seconds specified before giving up. The default should be
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more than enough for a unicast response. If \fBsntp\fP is
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only waiting for a broadcast response a longer timeout is
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likely needed.
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.TP
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.NOP \f\*[B-Font]\-\-wait\f[], \f\*[B-Font]\- Fl \-no\-wait\f[]
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Wait for pending replies (if not setting the time).
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The \fIno\-wait\fP form will disable the option.
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This option is enabled by default.
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.sp
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If we are not setting the time, wait for all pending responses.
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.TP
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.NOP \f\*[B-Font]\-\&?\f[], \f\*[B-Font]\-\-help\f[]
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Display usage information and exit.
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.TP
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.NOP \f\*[B-Font]\-\&!\f[], \f\*[B-Font]\-\-more-help\f[]
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Pass the extended usage information through a pager.
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.TP
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.NOP \f\*[B-Font]\->\f[] [\f\*[I-Font]cfgfile\f[]], \f\*[B-Font]\-\-save-opts\f[] [=\f\*[I-Font]cfgfile\f[]]
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Save the option state to \fIcfgfile\fP. The default is the \fIlast\fP
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configuration file listed in the \fBOPTION PRESETS\fP section, below.
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The command will exit after updating the config file.
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.TP
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.NOP \f\*[B-Font]\-<\f[] \f\*[I-Font]cfgfile\f[], \f\*[B-Font]\-\-load-opts\f[]=\f\*[I-Font]cfgfile\f[], \f\*[B-Font]\-\-no-load-opts\f[]
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Load options from \fIcfgfile\fP.
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The \fIno-load-opts\fP form will disable the loading
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of earlier config/rc/ini files. \fI\-\-no-load-opts\fP is handled early,
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out of order.
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.TP
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.NOP \f\*[B-Font]\-\-version\f[] [{\f\*[I-Font]v|c|n\f[]}]
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Output version of program and exit. The default mode is `v', a simple
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version. The `c' mode will print copyright information and `n' will
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print the full copyright notice.
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.PP
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.SH "OPTION PRESETS"
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Any option that is not marked as \fInot presettable\fP may be preset
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by loading values from configuration ("RC" or ".INI") file(s) and values from
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environment variables named:
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.nf
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\fBSNTP_<option-name>\fP or \fBSNTP\fP
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.fi
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.ad
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The environmental presets take precedence (are processed later than)
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the configuration files.
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The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP".
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If any of these are directories, then the file \fI.ntprc\fP
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is searched for within those directories.
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.SH USAGE
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.TP 7
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.NOP \f[C]sntp ntpserver.somewhere\f[]
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is the simplest use of this program
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and can be run as an unprivileged command
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to check the current time and error in the local clock.
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.TP 7
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.NOP \f[C]sntp \-Ss \-M 128 ntpserver.somewhere\f[]
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With suitable privilege,
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run as a command
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or from a
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\fCcron\f[]\fR(8)\f[]
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job,
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\f\*[B-Font]sntp \-Ss \-M 128 ntpserver.somewhere\f[]
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will request the time from the server,
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and if that server reports that it is synchronized
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then if the offset adjustment is less than 128 milliseconds
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the correction will be slewed,
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and if the correction is more than 128 milliseconds
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the correction will be stepped.
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.TP 7
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.NOP \f[C]sntp \-S ntpserver.somewhere\f[]
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With suitable privilege,
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run as a command
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or from a
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\fCcron\f[]\fR(8)\f[]
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job,
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\f\*[B-Font]sntp \-S ntpserver.somewhere\f[]
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will set (step) the local clock from a synchronized specified server,
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like the (deprecated)
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\fCntpdate\f[]\fR(@NTPDATE_MS@)\f[],
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or
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\fCrdate\f[]\fR(8)\f[]
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commands.
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.PP
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.SH "ENVIRONMENT"
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See \fBOPTION PRESETS\fP for configuration environment variables.
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.SH "FILES"
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See \fBOPTION PRESETS\fP for configuration files.
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.SH "EXIT STATUS"
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One of the following exit values will be returned:
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.TP
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.NOP 0 " (EXIT_SUCCESS)"
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Successful program execution.
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.TP
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.NOP 1 " (EXIT_FAILURE)"
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The operation failed or the command syntax was not valid.
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.TP
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.NOP 66 " (EX_NOINPUT)"
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A specified configuration file could not be loaded.
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.TP
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.NOP 70 " (EX_SOFTWARE)"
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libopts had an internal operational error. Please report
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it to autogen-users@lists.sourceforge.net. Thank you.
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.PP
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.SH AUTHORS
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.NOP "Johannes Maximilian Kuehn"
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.br
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.NOP "Harlan Stenn"
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.br
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.NOP "Dave Hart"
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.br
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.SH "COPYRIGHT"
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Copyright (C) 1992-2017 The University of Delaware and Network Time Foundation all rights reserved.
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This program is released under the terms of the NTP license, <http://ntp.org/license>.
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.SH "BUGS"
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Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
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.SH "NOTES"
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This manual page was \fIAutoGen\fP-erated from the \fBsntp\fP
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option definitions.
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