doc/offline.sgml

   1 <!doctype debiandoc system>
   2 <!-- -*- mode: sgml; mode: fold -*- -->
   3 <book>
   4 <title>Using APT Offline</title>
   5
   6 <author>Jason Gunthorpe <email>jgg@debian.org</email></author>
   7 <version>$Id: offline.sgml,v 1.3 2001/02/20 07:03:17 jgg Exp $</version>
   8
   9 <abstract>
  10 This document describes how to use APT in a non-networked environment,
  11 specifically a 'sneaker-net' approach for performing upgrades.
  12 </abstract>
  13
  14 <copyright>
  15 Copyright &copy; Jason Gunthorpe, 1999.
  16 <p>
  17 "APT" and this document are free software; you can redistribute them and/or
  18 modify them under the terms of the GNU General Public License as published
  19 by the Free Software Foundation; either version 2 of the License, or (at your
  20 option) any later version.
  21
  22 <p>
  23 For more details, on Debian GNU/Linux systems, see the file
  24 /usr/doc/copyright/GPL for the full license.
  25 </copyright>
  26
  27 <toc sect>
  28
  29 <chapt>Introduction
  30 <!-- Overview                                                          {{{ -->
  31 <!-- ===================================================================== -->
  32 <sect>Overview
  33
  34 <p>
  35 Normally APT requires direct access to a Debian archive, either from a local
  36 media or through a network. Another common complaint is that a Debian machine
  37 is on a slow link, such as a modem and another machine has a very fast
  38 connection but they are physically distant.
  39
  40 <p>
  41 The solution to this is to use large removable media such as a Zip disc or a
  42 SuperDisk disc. These discs are not large enough to store the entire Debian
  43 archive but can easily fit a subset large enough for most users. The idea
  44 is to use APT to generate a list of packages that are required and then fetch
  45 them onto the disc using another machine with good connectivity. It is
  46 even possible to use another Debian machine with APT or to use a completely
  47 different OS and a download tool like wget.
  48
  49 <p>
  50 This is achieved by creatively manipulating the APT configuration file. The
  51 essential premis to tell APT to look on a disc for it's archive files. Note
  52 that the disc should be formated with a filesystem that can handle long file
  53 names such as ext2, fat32 or vfat.
  54
  55 </sect>
  56                                                                   <!-- }}} -->
  57
  58 <chapt>Using APT on both machines
  59 <!-- Overview                                                          {{{ -->
  60 <!-- ===================================================================== -->
  61 <sect>Overview
  62
  63 <p>
  64 APT being available on both machines gives the simplest configuration. The
  65 basic idea is to place a copy of the status file on the disc and use the
  66 remote machine to fetch the latest package files and decide which packages to
  67 download. The disk directory structure should look like:
  68
  69 <example>
  70   /disc/
  71     archives/
  72        partial/
  73     lists/
  74        partial/
  75     status
  76     sources.list
  77     apt.conf
  78 </example>
  79
  80 </sect>
  81                                                                   <!-- }}} -->
  82 <!-- The configuartion file                                            {{{ -->
  83 <!-- ===================================================================== -->
  84 <sect>The configuration file
  85
  86 <p>
  87 The configuration file should tell APT to store its files on the disc and
  88 to use the configuration files on the disc as well. The sources.list should
  89 contain the proper sites that you wish to use from the remote machine, and
  90 the status file should be a copy of <em>/var/lib/dpkg/status</em>. Please note,
  91 if you are using a local archive you must use copy URIs, the syntax is identical
  92 to file URIs.
  93
  94 <p>
  95 <em>apt.conf</em> must contain the necessary information to make APT use the
  96 disc:
  97
  98 <example>
  99  APT
 100  {
 101    /* This is not necessary if the two machines are the same arch, it tells
 102       the remote APT what architecture the Debian machine is */
 103    Architecture "i386";
 104
 105    Get::Download-Only "true";
 106  };
 107
 108  Dir
 109  {
 110    /* Use the disc for state information and redirect the status file from
 111       the /var/lib/dpkg default */
 112    State "/disc/";
 113    State::status "status";
 114
 115    // Binary caches will be stored locally
 116    Cache::archives "/disc/archives/";
 117
 118    // Location of the source list.
 119    Etc "/disc/";
 120  };
 121 </example>
 122
 123 More details can be seen by examining the apt.conf man page and the sample
 124 configuration file in <em>/usr/doc/apt/examples/apt.conf</em>.
 125
 126 <p>
 127 On the remote Debian machine the first thing to do is mount the disc and copy
 128 <em>/var/lib/dpkg/status</em> to it. You will also need to create the directories
 129 outlined in the Overview, <em>archives/partial/</em> and <em>lists/partial/</em>
 130 Then take the disc to the remote machine and configure the sources.list.
 131 On the remote machine execute the following:
 132
 133 <example>
 134  # export APT_CONFIG="/disc/apt.conf"
 135  # apt-get update
 136  [ APT fetches the package files ]
 137  # apt-get dist-upgrade
 138  [ APT fetches all the packages needed to upgrade your machine ]
 139 </example>
 140
 141 The dist-upgrade command can be replaced with any-other standard APT commands,
 142 particularly dselect-upgrad. You can even use an APT front end such as
 143 <em>dselect</em> However this presents a problem in communicating your
 144 selections back to the local computer.
 145
 146 <p>
 147 Now the disc contains all of the index files and archives needed to upgrade
 148 the Debian machine. Take the disc back and run:
 149
 150 <example>
 151   # export APT_CONFIG="/disc/apt.conf"
 152   # apt-get check
 153   [ APT generates a local copy of the cache files ]
 154   # apt-get --no-d -o dir::etc::status=/var/lib/dpkg/status dist-upgrade
 155   [ Or any other APT command ]
 156 </example>
 157
 158 <p>
 159 It is necessary for proper function to re-specify the status file to be the
 160 local one. This is very important!
 161
 162 <p>
 163 If you are using dselect you can do the very risky operation of copying
 164 disc/status to /var/lib/dpkg/status so that any selections you made on the
 165 remote machine are updated. I highly recommend that people only make selections
 166 on the local machine - but this may not always be possible. DO NOT copy
 167 the status file if dpkg or APT have been run in the mean time!!
 168
 169 </sect>
 170                                                                   <!-- }}} -->
 171
 172 <chapt>Using APT and wget
 173 <!-- Overview                                                          {{{ -->
 174 <!-- ===================================================================== -->
 175 <sect>Overview
 176
 177 <p>
 178 <em>wget</em> is a popular and portable download tool that can run on nearly
 179 any machine. Unlike the method above this requires that the Debian machine
 180 already has a list of available packages.
 181
 182 <p>
 183 The basic idea is to create a disc that has only the archive files downloaded
 184 from the remote site. This is done by using the --print-uris option to apt-get
 185 and then preparing a wget script to actually fetch the packages.
 186
 187 </sect>
 188                                                                   <!-- }}} -->
 189 <!-- Operation                                                         {{{ -->
 190 <!-- ===================================================================== -->
 191 <sect>Operation
 192
 193 <p>
 194 Unlike the previous technique no special configuration files are required. We
 195 merely use the standard APT commands to generate the file list.
 196
 197 <example>
 198  # apt-get dist-upgrade
 199  [ Press no when prompted, make sure you are happy with the actions ]
 200  # apt-get -qq --print-uris dist-upgrade > uris
 201  # awk '{print "wget -O " $2 " " $1}' < uris > /disc/wget-script
 202 </example>
 203
 204 Any command other than dist-upgrade could be used here, including
 205 dselect-upgrade.
 206
 207 <p>
 208 The /disc/wget-script file will now contain a list of wget commands to execute
 209 in order to fetch the necessary archives. This script should be run with the
 210 current directory as the disc's mount point so as to save the output on the
 211 disc.
 212
 213 <p>
 214 The remote machine would do something like
 215
 216 <example>
 217   # cd /disc
 218   # sh -x ./wget-script
 219   [ wait.. ]
 220 </example>
 221
 222 Once the archives are downloaded and the disc returned to the Debian machine
 223 installation can proceed using,
 224
 225 <example>
 226   # apt-get -o dir::cache::archives="/disc/" dist-upgrade
 227 </example>
 228
 229 Which will use the already fetched archives on the disc.
 230
 231 </sect>
 232                                                                   <!-- }}} -->
 233 </book>