<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE fileref SYSTEM "fileref.dtd">

<fileref>
  <header>
    <copyright>
      <year>1997</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.
  You may obtain a copy of the License at
 
      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  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
      <seemfa marker="systools#make_relup/3"><c>systools:make_relup/3,4</c></seemfa>, 
      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 is to be located in
      directory <c>$ROOT/releases/Vsn</c>.</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>
    <taglist>
      <tag><c>Vsn = string()</c></tag>
        <item><p>Current release version.</p></item>
      <tag><c>UpFromVsn = string()</c></tag>
        <item><p>Earlier version of the release to upgrade from.</p></item>
      <tag><c>Descr = term()</c></tag>
        <item><p>A user-defined parameter passed
          from the function 
	  <seemfa marker="systools#make_relup/3"><c>systools:make_relup/3,4</c></seemfa>.
	  It is used in the return value of
          <seemfa marker="release_handler#install_release/1"><c>release_handler:install_release/1,2</c></seemfa>.</p></item>
      <tag><c>Instructions</c></tag>
        <item><p>A list of low-level release upgrade instructions, see
          <seefile marker="appup"><c>appup(4)</c></seefile>.
          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>
      <tag><c>DownToVsn = string()</c></tag>
        <item><p>Earlier version of the release to downgrade to.</p></item>
    </taglist>
  </section>

  <section>
    <title>See Also</title>
    <p><seefile marker="kernel:app"><c>app(4)</c></seefile>,
      <seefile marker="appup"><c>appup(4)</c></seefile>,
      <seefile marker="rel"><c>rel(4)</c></seefile>,
      <seeerl marker="release_handler"><c>release_handler(3)</c></seeerl>,
      <seeerl marker="systools"><c>systools(3)</c></seeerl></p>
  </section>
</fileref>

