# ntpdc: NTPD Control User’s Manual

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# ntpdc: NTPD Control User Manual

This document describes the use of the NTP Project’s `ntpdc` program, that can be used to query a Network Time Protocol (NTP) server and display the time offset of the system clock relative to the server clock. Run as root, it can correct the system clock to this offset as well. It can be run as an interactive command or from a cron job.

This document applies to version 4.2.8p18 of `ntpdc`.

The program implements the SNTP protocol as defined by RFC 5905, the NTPv4 IETF specification.

## Short Table of Contents

- 1 Description

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## 1 Description

By default, `ntpdc` writes the local data and time (i.e., not UTC) to the standard output in the format:

    1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs

where YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time, (+0800) is the local timezone adjustment (so we would add 8 hours and 0 minutes to convert the reported local time to UTC), and the +4.567 +/- 0.089 secs indicates the time offset and error bound of the system clock relative to the server clock.

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### 1.1 Invoking ntpdc

`ntpdc` is deprecated. Please use `ntpq(1ntpqmdoc)` instead - it can do everything `ntpdc` used to do, and it does so using a much more sane interface.

`ntpdc` is a utility program used to query `ntpd(1ntpdmdoc)` about its current state and to request changes in that state. It uses NTP mode 7 control message formats described in the source code. The program may be run either in interactive mode or controlled using command line arguments. Extensive state and statistics information is available through the `ntpdc` interface. In addition, nearly all the configuration options which can be specified at startup using ntpd’s configuration file may also be specified at run time using `ntpdc`

This section was generated by AutoGen, using the `agtexi-cmd` template and the option descriptions for the `ntpdc` program. This software is released under the NTP license, <http://ntp.org/license>.

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#### 1.1.1 ntpdc help/usage (`--help`)

This is the automatically generated usage text for ntpdc.

The text printed is the same whether selected with the `help` option (`--help`) or the `more-help` option (`--more-help`). `more-help` will print the usage text by passing it through a pager program. `more-help` is disabled on platforms without a working `fork(2)` function. The `PAGER` environment variable is used to select the program, defaulting to `more`. Both will exit with a status code of 0.

    ntpdc - vendor-specific NTPD control program - Ver. 4.2.8p18
    Usage:  ntpdc [ -<flag> [<val>] | --<name>[{=| }<val>] ]... [ host ...]
      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'
       -c Str command        run a command and exit
                                    - may appear multiple times
       -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
       -i no  interactive    Force ntpq to operate in interactive mode
                                    - prohibits these options:
                                    command
                                    listpeers
                                    peers
                                    showpeers
       -l no  listpeers      Print a list of the peers
                                    - prohibits the option 'command'
       -n no  numeric        numeric host addresses
       -p no  peers          Print a list of the peers
                                    - prohibits the option 'command'
       -s no  showpeers      Show a list of the peers
                                    - prohibits the option 'command'
       -u no  unconnected    Use unconnected UDP to communicate with ntpd (default on Windows)
          opt version        output version information and exit
       -? no  help           display extended usage information and exit
       -! no  more-help      extended usage information passed thru pager
       -> opt save-opts      save the option state to a config file
       -< Str load-opts      load options from a config file
                                    - disabled as '--no-load-opts'
                                    - may appear multiple times

    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:
     - reading file $HOME/.ntprc
     - reading file ./.ntprc
     - examining environment variables named NTPDC_*

    Please send bug reports to:  <https://bugs.ntp.org, bugs@ntp.org>

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#### 1.1.2 ipv4 option (-4)

This is the “force ipv4 dns name resolution” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: ipv6.

Force DNS resolution of following host names on the command line to the IPv4 namespace.

Next: ntpdc command, Previous: ntpdc ipv4, Up: ntpdc Invocation

#### 1.1.3 ipv6 option (-6)

This is the “force ipv6 dns name resolution” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: ipv4.

Force DNS resolution of following host names on the command line to the IPv6 namespace.

Next: ntpdc interactive, Previous: ntpdc ipv6, Up: ntpdc Invocation

#### 1.1.4 command option (-c)

This is the “run a command and exit” option. This option takes a string argument `cmd`.

This option has some usage constraints. It:

- may appear an unlimited number of times.

The following argument is interpreted as an interactive format command and is added to the list of commands to be executed on the specified host(s).

Next: ntpdc listpeers, Previous: ntpdc command, Up: ntpdc Invocation

#### 1.1.5 interactive option (-i)

This is the “force ntpq to operate in interactive mode” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: command, listpeers, peers, showpeers.

Force ntpq to operate in interactive mode. Prompts will be written to the standard output and commands read from the standard input.

Next: ntpdc numeric, Previous: ntpdc interactive, Up: ntpdc Invocation

#### 1.1.6 listpeers option (-l)

This is the “print a list of the peers” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: command.

Print a list of the peers known to the server as well as a summary of their state. This is equivalent to the ’listpeers’ interactive command.

Next: ntpdc peers, Previous: ntpdc listpeers, Up: ntpdc Invocation

#### 1.1.7 numeric option (-n)

This is the “numeric host addresses” option. Output all host addresses in dotted-quad numeric format rather than converting to the canonical host names.

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#### 1.1.8 peers option (-p)

This is the “print a list of the peers” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: command.

Print a list of the peers known to the server as well as a summary of their state. This is equivalent to the ’peers’ interactive command.

Next: ntpdc unconnected, Previous: ntpdc peers, Up: ntpdc Invocation

#### 1.1.9 showpeers option (-s)

This is the “show a list of the peers” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: command.

Print a list of the peers known to the server as well as a summary of their state. This is equivalent to the ’dmpeers’ interactive command.

Next: ntpdc config, Previous: ntpdc showpeers, Up: ntpdc Invocation

#### 1.1.10 unconnected option (-u)

This is the “use unconnected udp to communicate with ntpd (default on windows)” option. Open an unconnected UDP association to ntpd (the default on Windows).

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#### 1.1.11 presetting/configuring ntpdc

Any option that is not marked as not presettable may be preset by loading values from configuration ("rc" or "ini") files, and values from environment variables named `NTPDC` and `NTPDC_<OPTION_NAME>`. `<OPTION_NAME>` must be one of the options listed above in upper case and segmented with underscores. The `NTPDC` 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.

`libopts` will search in 2 places for configuration files:

- $HOME
- $PWD

The environment variables `HOME`, and `PWD` are expanded and replaced when `ntpdc` runs. For any of these that are plain files, they are simply processed. For any that are directories, then a file named `.ntprc` is searched for within that directory and processed.

Configuration files may be in a wide variety of formats. The basic format is an option name followed by a value (argument) on the same line. Values may be separated from the option name with a colon, equal sign or simply white space. Values may be continued across multiple lines by escaping the newline with a backslash.

Multiple programs may also share the same initialization file. Common options are collected at the top, followed by program specific segments. The segments are separated by lines like:

    [NTPDC]

or by

    <?program ntpdc>

Do not mix these styles within one configuration file.

Compound values and carefully constructed string values may also be specified using XML syntax:

    <option-name>
       <sub-opt>...&lt;...&gt;...</sub-opt>
    </option-name>

yielding an `option-name.sub-opt` string value of

    "...<...>..."

`AutoOpts` does not track suboptions. You simply note that it is a hierarchicly valued option. `AutoOpts` does provide a means for searching the associated name/value pair list (see: optionFindValue).

The command line options relating to configuration and/or usage help are:

#### version (-)

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 information may be selected with an option argument. Only the first letter of the argument is examined:

‘`version`’

  Only print the version. This is the default.

‘`copyright`’

  Name the copyright usage licensing terms.

‘`verbose`’

  Print the full copyright usage licensing terms.

Next: ntpdc Usage, Previous: ntpdc config, Up: ntpdc Invocation

#### 1.1.12 ntpdc exit status

One of the following exit values will be returned:

‘`0 (EXIT_SUCCESS)`’

  Successful program execution.

‘`1 (EXIT_FAILURE)`’

  The operation failed or the command syntax was not valid.

‘`66 (EX_NOINPUT)`’

  A specified configuration file could not be loaded.

‘`70 (EX_SOFTWARE)`’

  libopts had an internal operational error. Please report it to autogen-users@lists.sourceforge.net. Thank you.

Next: ntpdc See Also, Previous: ntpdc exit status, Up: ntpdc Invocation

#### 1.1.13 ntpdc Usage

Next: ntpdc Authors, Previous: ntpdc Usage, Up: ntpdc Invocation

#### 1.1.14 ntpdc See Also

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#### 1.1.15 ntpdc Authors

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#### 1.1.16 ntpdc Bugs

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### 1.2 Usage

The simplest use of this program is as an unprivileged command to check the current time, offset, and error in the local clock. For example:

    ntpdc ntpserver.somewhere

With suitable privilege, it can be run as a command or in a `cron` job to reset the local clock from a reliable server, like the `ntpdate` and `rdate` commands. For example:

    ntpdc -a ntpserver.somewhere