#include copyright.def
prog-name = "sntp";
-prog-title = "standard Simple Network Time Protocol program";
+prog-title = "standard Simple Network Time Protocol client program";
argument = '[ hostname-or-IP ...]';
#include homerc.def
Requests from an NTP "client" to a "server" should never be sent
more rapidly than one every 2 seconds. By default, any IPs returned
as part of a DNS lookup are assumed to be for a single instance of
- ntpd, and therefore @code{sntp} will send queries to these IPs one after
- another, with a 2-second gap in between each query.
+ ntpd, and therefore @code{sntp} will send queries to these IPs one
+ after another, with a 2-second gap in between each query.
- The -c or --concurrent flag says that any IPs returned for the DNS
- lookup of the supplied host-name are on different machines, so we
- can send concurrent queries.
+ The @code{-c} or @code{--concurrent} flag says that any IPs
+ returned for the DNS lookup of the supplied host-name are on
+ different machines, so we can send concurrent queries.
_EndOfDoc_;
};
arg-name = "file-name";
doc = <<- _EndOfDoc_
This option specifies the keyfile.
- @code{sntp} will search for the key specified with -a keyno in this
- file. Key files follow the following format:
+ @code{sntp} will search for the key specified with @code{-a}
+ @file{keyno} in this file. Key files follow the following format:
- keyid keytype key
+ @file{keyid keytype key}
- Where keyid is a number identifying this key
- keytype is one of the following:
- S Key is a 64 Bit hexadecimal number as specified in in the DES specification.
- N Key is a 64 Bit hexadecimal number as specified in the NTP standard.
- A Key is a 1-to-8 character ASCII string.
- M Key is a 1-to-8 character ASCII string using the MD5 authentication scheme.
+ Where @file{keyid} is a number identifying this key
+ @file{keytype} is one of the following:
+ @code{S} Key is a 64 Bit hexadecimal number as specified in in the DES specification.
+ @code{N} Key is a 64 Bit hexadecimal number as specified in the NTP standard.
+ @code{A} Key is a 1-to-8 character ASCII string.
+ @code{M} Key is a 1-to-8 character ASCII string using the MD5 authentication scheme.
For more information see ntp.keys(5).
_EndOfDoc_;
descrip = "Log to specified logfile";
doc = <<- _EndOfDoc_
This option causes the client to write log messages to the specified
- logfile.
+ @file{logfile}.
_EndOfDoc_;
};
value = M;
arg-type = number;
arg-range = "0->";
- descrip = "Adjustments less than steplimit msec will be slewed";
+ descrip = "Adjustments less than @file{steplimit} msec will be slewed";
doc = <<- _EndOfDoc_
- If the time adjustment is less than steplimit milliseconds, slew the
- amount using adjtime(). Otherwise, step the correction using
- settimeofday().
+ If the time adjustment is less than @file{steplimit} milliseconds,
+ slew the amount using adjtime(2). Otherwise, step the correction
+ using settimeofday(2).
_EndOfDoc_;
};
arg-range = "0->7";
doc = <<- _EndOfDoc_
When sending requests to a remote server, tell them we are running
- NTP protocol version <ntpversion> .
+ NTP protocol version @file{ntpversion} .
_EndOfDoc_;
};
flag = {
name = step;
value = S;
- descrip = "OK to 'step' the time with settimeofday()";
+ descrip = "OK to 'step' the time with settimeofday(2)";
doc = <<- _EndOfDoc_
_EndOfDoc_;
};
flag = {
name = slew;
value = s;
- descrip = "OK to 'slew' the time with adjtime()";
+ descrip = "OK to 'slew' the time with adjtime(2)";
doc = <<- _EndOfDoc_
_EndOfDoc_;
};
.Nm
can be used as an SNTP client to query a NTP or SNTP server and either display
the time or set the local system's time (given suitable privilege). It can be
-run as an interactive command or in a
+run as an interactive command or from a
.Ic cron
job.
The default is to write the estimated correct local date and time (i.e. not
UTC) to the standard output in a format like:
-.Ic "'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs'"
+.Ic "'1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN'"
where the
.Ic "'(+0800)'"
means that to get to UTC from the reported local time one must
add 8 hours and 0 minutes,
-and the
-.Ic "'+4.567 +/- 0.089 secs'"
+the
+.Ic "'+4.567'"
indicates the local clock is 4.567 seconds behind the correct time
-(so 4.567 seconds must be added to the local clock to get it to be correct),
-and the date/time of
-'1996-10-15 20:17:25.123'
-is believed to be correct to within
-+/- 0.089
-seconds.
+(so 4.567 seconds must be added to the local clock to get it to be correct).
+Note that the number of decimals printed for this value will change
+based on the reported precision of the server.
+.Ic "'+/- 0.089'"
+is the reported
+.Em synchronization distance
+(in seconds), which represents the maximum error due to all causes.
+If the server does not report valid data needed to calculate the
+synchronization distance, this will be reported as
+.Ic "'+/- ?'" .
+If the
+.Em host
+is different from the
+.Em IP ,
+both will be displayed.
+Otherwise, only the
+.Em IP
+is displayed.
+Finally, the
+.Em stratum
+of the host is reported.
_END_PROG_MDOC_DESCRIP;
};
The default is to write the estimated correct local date and time (i.e. not
UTC) to the standard output in a format like
@example
-1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
+1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN
@end example
where the
@example
-+4.567 +/- 0.089 secs
+(+0800)
+@end example
+means that to get to UTC from the reported local time one must
+add 8 hours and 0 minutes,
+the
+@example
++4.567
@end example
indicates the local clock is 4.567 seconds behind the correct time
-(so 4.567 seconds must be added to the local clock to get it to be correct),
-and the (local) time of
-@code{1996-10-15 20:17:25.123}
-can be converted to UTC time by adding 8 hours and 0 minutes, and
-is believed to be correct to within
-@code{+/- 0.089}
-seconds.
+(so 4.567 seconds must be added to the local clock to get it to be correct).
+Note that the number of decimals printed for this value will change
+based on the reported precision of the server.
+@example
++/- 0.089
+@end example
+is the reported @file{synchronization distance} (in seconds),
+which represents the maximum error due to all causes.
+If the server does not report valid data needed to calculate the
+synchronization distance, this will be reported as
+@example
++/- ?
+@end example
+If the @file{host} is different from the @file{IP}, both will be displayed.
+Otherwise, only the @file{IP} is displayed.
+Finally, the @file{stratum} is reported.
_END_PROG_INFO_DESCRIP;
doc-section = {
projects / thirdparty / ntp.git / commitdiff
