path: root/lib/sasl/doc/src/relup.xml

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  <header>
    <copyright>
      <year>1997</year>
      <year>2013</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
  The contents of this file are subject to the Erlang Public License,
  Version 1.1, (the "License"); you may not use this file except in
  compliance with the License. You should have received a copy of the
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  The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>

    <title>relup</title>
    <prepared></prepared>
    <docno></docno>
    <date></date>
    <rev></rev>
  </header>
  <file>relup</file>
  <filesummary>Release upgrade file</filesummary>
  <description>
    <p>The <em>release upgrade file</em> describes how a release is
      upgraded in a running system.</p>
    <p>This file is automatically generated by
      <c>systools:make_relup/3,4</c>, using a release resource file
      (<c>.rel</c>), application resource files (<c>.app</c>) and
      application upgrade files (<c>.appup</c>) as input.</p>
  </description>

  <section>
    <title>FILE SYNTAX</title>
    <p>In a target system, the release upgrade file should be located in
      the <c>OTP_ROOT/erts-EVsn/Vsn</c> directory.</p>
    <p>The <c>relup</c> file contains one single Erlang term, which
      defines the instructions used to upgrade the release. The file has
      the following syntax:</p>
    <code type="none">
{Vsn,
  [{UpFromVsn, Descr, Instructions}, ...],
  [{DownToVsn, Descr, Instructions}, ...]}.
    </code>
    <list type="bulleted">
      <item>
        <p><c>Vsn = string()</c> is the current version of the release.</p>
      </item>
      <item>
        <p><c>UpFromVsn = string()</c> is an earlier version of the release
          to upgrade from.</p>
      </item>
      <item>
        <p><c>Descr = term()</c> is a user defined parameter passed
          from the <c>systools:make_relup/3,4</c> function. It will
          be used in the return value of
          <c>release_handler:install_release/1,2</c>.</p>
      </item>
      <item>
        <p><c>Instructions</c> is a list of low-level release upgrade
          instructions, see <c>appup(4)</c>.</p>
        <p>It consists of the release upgrade instructions from
          the respective application upgrade files (high-level instructions
          are translated to low-level instructions), in the same order
          as in the start script.</p>
      </item>
      <item>
        <p><c>DownToVsn = string()</c> is an earlier version of the release
          to downgrade to.</p>
      </item>
    </list>
    <p>When upgrading from <c>UpFromVsn</c> with
      <c>release_handler:install_release/1,2</c>, there does not have to be
      an exact match of versions, but <c>UpFromVsn</c> can be a sub-string
      of the current release version.</p>
  </section>

  <section>
    <title>SEE ALSO</title>
    <p>app(4), appup(4), rel(4), release_handler(3), systools(3)</p>
  </section>
</fileref>