path: root/lib/kernel/doc/src/net_adm.xml

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  <header>
    <copyright>
      <year>1996</year><year>2016</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
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          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
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      See the License for the specific language governing permissions and
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    </legalnotice>

    <title>net_adm</title>
    <prepared>Claes Wikstrom</prepared>
    <docno>1</docno>
    <date>96-09-10</date>
    <rev>A</rev>
  </header>
  <module>net_adm</module>
  <modulesummary>Various Erlang Net Administration Routines</modulesummary>
  <description>
    <p>This module contains various network utility functions.</p>
  </description>
  <funcs>
    <func>
      <name name="dns_hostname" arity="1"/>
      <fsummary>Official name of a host</fsummary>
      <desc>
        <p>Returns the official name of <c><anno>Host</anno></c>, or
          <c>{error, <anno>Host</anno>}</c> if no such name is found. See also
          <c>inet(3)</c>.</p>
      </desc>
    </func>
    <func>
      <name name="host_file" arity="0"/>
      <fsummary>Read the <c>.hosts.erlang</c>file</fsummary>
      <desc>
        <p>Reads the <c>.hosts.erlang</c> file, see the section
          <em>Files</em> below. Returns the hosts in this file as a
          list, or returns <c>{error, <anno>Reason</anno>}</c> if the file could not
          be read or the Erlang terms on the file could not be interpreted.</p>
      </desc>
    </func>
    <func>
      <name name="localhost" arity="0"/>
      <fsummary>Name of the local host</fsummary>
      <desc>
        <p>Returns the name of the local host. If Erlang was started
          with the <c>-name</c> command line flag, <c><anno>Name</anno></c> is
          the fully qualified name.</p>
      </desc>
    </func>
    <func>
      <name name="names" arity="0"/>
      <name name="names" arity="1"/>
      <fsummary>Names of Erlang nodes at a host</fsummary>
      <desc>
        <p>Similar to <c>epmd -names</c>, see <c>epmd(1)</c>.
          <c><anno>Host</anno></c> defaults to the local host. Returns the names and
          associated port numbers of the Erlang nodes that <c>epmd</c>
          at the specified host has registered.</p>
        <p>Returns <c>{error, address}</c> if <c>epmd</c> is not
          running.</p>
        <pre>
(arne@dunn)1> <input>net_adm:names().</input>
{ok,[{"arne",40262}]}</pre>
      </desc>
    </func>
    <func>
      <name name="ping" arity="1"/>
      <fsummary>Set up a connection to a node</fsummary>
      <desc>
        <p>Tries to set up a connection to <c><anno>Node</anno></c>. Returns
          <c>pang</c> if it fails, or <c>pong</c> if it is successful.</p>
      </desc>
    </func>
    <func>
      <name name="world" arity="0"/>
      <name name="world" arity="1"/>
      <fsummary>Lookup and connect to all nodes at all hosts in <c>.hosts.erlang</c></fsummary>
      <type name="verbosity"/>
      <desc>
        <p>This function calls <c>names(Host)</c> for all hosts which
          are specified in the Erlang host file <c>.hosts.erlang</c>,
          collects the replies and then evaluates <c>ping(Node)</c> on
          all those nodes. Returns the list of all nodes that were,
	  successfully pinged.</p>
        <p><c><anno>Arg</anno></c> defaults to <c>silent</c>.
	 If <c><anno>Arg</anno> == verbose</c>, the function writes information about which
          nodes it is pinging to stdout.</p>
        <p>This function can be useful when a node is started, and
          the names of the other nodes in the network are not initially
          known.</p>
        <p>Failure: <c>{error, Reason}</c> if <c>host_file()</c>
          returns <c>{error, Reason}</c>.</p>
      </desc>
    </func>
    <func>
      <name name="world_list" arity="1"/>
      <name name="world_list" arity="2"/>
      <fsummary>Lookup and connect to all nodes at specified hosts</fsummary>
      <type name="verbosity"/>
      <desc>
        <p>As <c>world/0,1</c>, but the hosts are given as argument
          instead of being read from <c>.hosts.erlang</c>.</p>
      </desc>
    </func>
  </funcs>

  <section>
    <title>Files</title>
    <p>The <c>.hosts.erlang</c> file consists of a number of host names
      written as Erlang terms. It is looked for in the current work
      directory, the user's home directory, and <c>$OTP_ROOT</c>
      (the root directory of Erlang/OTP), in that order.</p>
    <p>The format of the <c>.hosts.erlang</c> file must be one host
      name per line. The host names must be within quotes as shown in
      the following example:</p>
    <pre>
'super.eua.ericsson.se'.
'renat.eua.ericsson.se'.
'grouse.eua.ericsson.se'.
'gauffin1.eua.ericsson.se'.
^ (new line)</pre>
  </section>
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