213 lines
7.7 KiB
Plaintext
213 lines
7.7 KiB
Plaintext
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">
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<!--
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- Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
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- Copyright (C) 2000-2002 Internet Software Consortium.
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-
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- Permission to use, copy, modify, and distribute this software for any
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- purpose with or without fee is hereby granted, provided that the above
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- copyright notice and this permission notice appear in all copies.
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-
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- THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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- AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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- PERFORMANCE OF THIS SOFTWARE.
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-->
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<!-- $Id: host.docbook,v 1.2.2.2.4.5 2004/04/13 01:26:26 marka Exp $ -->
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<refentry>
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<refentryinfo>
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<date>Jun 30, 2000</date>
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</refentryinfo>
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<refmeta>
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<refentrytitle>host</refentrytitle>
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<manvolnum>1</manvolnum>
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<refmiscinfo>BIND9</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>host</refname>
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<refpurpose>DNS lookup utility</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>host</command>
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<arg><option>-aCdlnrTwv</option></arg>
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<arg><option>-c <replaceable class="parameter">class</replaceable></option></arg>
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<arg><option>-N <replaceable class="parameter">ndots</replaceable></option></arg>
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<arg><option>-R <replaceable class="parameter">number</replaceable></option></arg>
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<arg><option>-t <replaceable class="parameter">type</replaceable></option></arg>
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<arg><option>-W <replaceable class="parameter">wait</replaceable></option></arg>
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<arg><option>-4</option></arg>
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<arg><option>-6</option></arg>
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<arg choice=req>name</arg>
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<arg choice=opt>server</arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>DESCRIPTION</title>
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<para>
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<command>host</command>
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is a simple utility for performing DNS lookups.
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It is normally used to convert names to IP addresses and vice versa.
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When no arguments or options are given,
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<command>host</command>
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prints a short summary of its command line arguments and options.
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</para>
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<para>
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<parameter>name</parameter> is the domain name that is to be looked
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up. It can also be a dotted-decimal IPv4 address or a colon-delimited
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IPv6 address, in which case <command>host</command> will by default
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perform a reverse lookup for that address.
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<parameter>server</parameter> is an optional argument which is either
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the name or IP address of the name server that <command>host</command>
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should query instead of the server or servers listed in
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<filename>/etc/resolv.conf</filename>.
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</para>
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<para>
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The <option>-a</option> (all) option is equivalent to setting the
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<option>-v</option> option and asking <command>host</command> to make
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a query of type ANY.
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</para>
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<para>
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When the <option>-C</option> option is used, <command>host</command>
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will attempt to display the SOA records for zone
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<parameter>name</parameter> from all the listed authoritative name
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servers for that zone. The list of name servers is defined by the NS
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records that are found for the zone.
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</para>
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<para>
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The <option>-c</option> option instructs to make a DNS query of class
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<parameter>class</parameter>. This can be used to lookup Hesiod or
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Chaosnet class resource records. The default class is IN (Internet).
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</para>
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<para>
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Verbose output is generated by <command>host</command> when the
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<option>-d</option> or <option>-v</option> option is used. The two
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options are equivalent. They have been provided for backwards
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compatibility. In previous versions, the <option>-d</option> option
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switched on debugging traces and <option>-v</option> enabled verbose
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output.
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</para>
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<para>
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List mode is selected by the <option>-l</option> option. This makes
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<command>host</command> perform a zone transfer for zone
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<parameter>name</parameter>. Transfer the zone printing out the NS, PTR
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and address records (A/AAAA). If combined with <option>-a</option>
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all records will be printed.
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</para>
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<para>
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The <option>-i</option>
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option specifies that reverse lookups of IPv6 addresses should
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use the IP6.INT domain as defined in RFC1886.
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The default is to use IP6.ARPA.
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</para>
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<para>
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The <option>-N</option> option sets the number of dots that have to be
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in <parameter>name</parameter> for it to be considered absolute. The
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default value is that defined using the ndots statement in
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<filename>/etc/resolv.conf</filename>, or 1 if no ndots statement is
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present. Names with fewer dots are interpreted as relative names and
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will be searched for in the domains listed in the <type>search</type>
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or <type>domain</type> directive in
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<filename>/etc/resolv.conf</filename>.
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</para>
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<para>
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The number of UDP retries for a lookup can be changed with the
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<option>-R</option> option. <parameter>number</parameter> indicates
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how many times <command>host</command> will repeat a query that does
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not get answered. The default number of retries is 1. If
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<parameter>number</parameter> is negative or zero, the number of
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retries will default to 1.
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</para>
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<para>
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Non-recursive queries can be made via the <option>-r</option> option.
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Setting this option clears the <type>RD</type> — recursion
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desired — bit in the query which <command>host</command> makes.
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This should mean that the name server receiving the query will not
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attempt to resolve <parameter>name</parameter>. The
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<option>-r</option> option enables <command>host</command> to mimic
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the behaviour of a name server by making non-recursive queries and
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expecting to receive answers to those queries that are usually
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referrals to other name servers.
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</para>
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<para>
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By default <command>host</command> uses UDP when making queries. The
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<option>-T</option> option makes it use a TCP connection when querying
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the name server. TCP will be automatically selected for queries that
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require it, such as zone transfer (AXFR) requests.
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</para>
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<para>
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The <option>-4</option> option forces <command>host</command> to only
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use IPv4 query transport. The <option>-6</option> option forces
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<command>host</command> to only use IPv6 query transport.
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</para>
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<para>
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The <option>-t</option> option is used to select the query type.
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<parameter>type</parameter> can be any recognised query type: CNAME,
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NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
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<command>host</command> automatically selects an appropriate query
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type. By default it looks for A records, but if the
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<option>-C</option> option was given, queries will be made for SOA
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records, and if <parameter>name</parameter> is a dotted-decimal IPv4
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address or colon-delimited IPv6 address, <command>host</command> will
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query for PTR records. If a query type of IXFR is chosen the starting
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serial number can be specified by appending an equal followed by the
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starting serial number (e.g. -t IXFR=12345678).
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</para>
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<para>
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The time to wait for a reply can be controlled through the
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<option>-W</option> and <option>-w</option> options. The
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<option>-W</option> option makes <command>host</command> wait for
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<parameter>wait</parameter> seconds. If <parameter>wait</parameter>
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is less than one, the wait interval is set to one second. When the
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<option>-w</option> option is used, <command>host</command> will
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effectively wait forever for a reply. The time to wait for a response
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will be set to the number of seconds given by the hardware's maximum
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value for an integer quantity.
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</para>
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</refsect1>
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<refsect1>
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<title>FILES</title>
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<para>
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<filename>/etc/resolv.conf</filename>
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</para>
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</refsect1>
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<refsect1>
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<title>SEE ALSO</title>
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<para>
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<citerefentry>
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<refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>.
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</para>
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</refsect1>
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</refentry>
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