doc/offline.sgml

   1 <!-- -*- mode: sgml; mode: fold -*- -->
   2 <!doctype debiandoc  PUBLIC  "-//DebianDoc//DTD DebianDoc//EN">
   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 1.8 2003/02/12 15:06:41 doogie 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/share/common-licenses/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. Let <em>remote host</em> mean the
  48 machine downloading the packages, and <em>target host</em> the one with bad or
  49 no connection.
  50
  51 <p>
  52 This is achieved by creatively manipulating the APT configuration file. The
  53 essential premise to tell APT to look on a disc for it's archive files. Note
  54 that the disc should be formated with a filesystem that can handle long file
  55 names such as ext2, fat32 or vfat.
  56
  57 </sect>
  58                                                                   <!-- }}} -->
  59
  60 <chapt>Using APT on both machines
  61 <!-- Overview                                                          {{{ -->
  62 <!-- ===================================================================== -->
  63 <sect>Overview
  64
  65 <p>
  66 APT being available on both machines gives the simplest configuration. The
  67 basic idea is to place a copy of the status file on the disc and use the
  68 remote machine to fetch the latest package files and decide which packages to
  69 download. The disk directory structure should look like:
  70
  71 <example>
  72   /disc/
  73     archives/
  74        partial/
  75     lists/
  76        partial/
  77     status
  78     sources.list
  79     apt.conf
  80 </example>
  81
  82 </sect>
  83                                                                   <!-- }}} -->
  84 <!-- The configuartion file                                            {{{ -->
  85 <!-- ===================================================================== -->
  86 <sect>The configuration file
  87
  88 <p>
  89 The configuration file should tell APT to store its files on the disc and
  90 to use the configuration files on the disc as well. The sources.list should
  91 contain the proper sites that you wish to use from the remote machine, and
  92 the status file should be a copy of <em>/var/lib/dpkg/status</em> from the
  93 <em>target host</em>. Please note, if you are using a local archive you must use
  94 copy URIs, the syntax is identical to file URIs.
  95
  96 <p>
  97 <em>apt.conf</em> must contain the necessary information to make APT use the
  98 disc:
  99
 100 <example>
 101  APT
 102  {
 103    /* This is not necessary if the two machines are the same arch, it tells
 104       the remote APT what architecture the target machine is */
 105    Architecture "i386";
 106
 107    Get::Download-Only "true";
 108  };
 109
 110  Dir
 111  {
 112    /* Use the disc for state information and redirect the status file from
 113       the /var/lib/dpkg default */
 114    State "/disc/";
 115    State::status "status";
 116
 117    // Binary caches will be stored locally
 118    Cache::archives "/disc/archives/";
 119    Cache "/tmp/";
 120
 121    // Location of the source list.
 122    Etc "/disc/";
 123  };
 124 </example>
 125
 126 More details can be seen by examining the apt.conf man page and the sample
 127 configuration file in <em>/usr/share/doc/apt/examples/apt.conf</em>.
 128
 129 <p>
 130 On the target machine the first thing to do is mount the disc and copy
 131 <em>/var/lib/dpkg/status</em> to it. You will also need to create the directories
 132 outlined in the Overview, <em>archives/partial/</em> and <em>lists/partial/</em>.
 133 Then take the disc to the remote machine and configure the sources.list.
 134 On the remote machine execute the following:
 135
 136 <example>
 137  # export APT_CONFIG="/disc/apt.conf"
 138  # apt-get update
 139  [ APT fetches the package files ]
 140  # apt-get dist-upgrade
 141  [ APT fetches all the packages needed to upgrade the target machine ]
 142 </example>
 143
 144 The dist-upgrade command can be replaced with any other standard APT commands,
 145 particularly dselect-upgrade. You can even use an APT front end such as
 146 <em>dselect</em>. However this presents a problem in communicating your
 147 selections back to the local computer.
 148
 149 <p>
 150 Now the disc contains all of the index files and archives needed to upgrade
 151 the target machine. Take the disc back and run:
 152
 153 <example>
 154   # export APT_CONFIG="/disc/apt.conf"
 155   # apt-get check
 156   [ APT generates a local copy of the cache files ]
 157   # apt-get --no-d -o dir::state::status=/var/lib/dpkg/status dist-upgrade
 158   [ Or any other APT command ]
 159 </example>
 160
 161 <p>
 162 It is necessary for proper function to re-specify the status file to be the
 163 local one. This is very important!
 164
 165 <p>
 166 If you are using dselect you can do the very risky operation of copying
 167 disc/status to /var/lib/dpkg/status so that any selections you made on the
 168 remote machine are updated. I highly recommend that people only make selections
 169 on the local machine - but this may not always be possible. DO NOT copy
 170 the status file if dpkg or APT have been run in the mean time!!
 171
 172 </sect>
 173                                                                   <!-- }}} -->
 174
 175 <chapt>Using APT and wget
 176 <!-- Overview                                                          {{{ -->
 177 <!-- ===================================================================== -->
 178 <sect>Overview
 179
 180 <p>
 181 <em>wget</em> is a popular and portable download tool that can run on nearly
 182 any machine. Unlike the method above this requires that the Debian machine
 183 already has a list of available packages.
 184
 185 <p>
 186 The basic idea is to create a disc that has only the archive files downloaded
 187 from the remote site. This is done by using the --print-uris option to apt-get
 188 and then preparing a wget script to actually fetch the packages.
 189
 190 </sect>
 191                                                                   <!-- }}} -->
 192 <!-- Operation                                                         {{{ -->
 193 <!-- ===================================================================== -->
 194 <sect>Operation
 195
 196 <p>
 197 Unlike the previous technique no special configuration files are required. We
 198 merely use the standard APT commands to generate the file list.
 199
 200 <example>
 201  # apt-get dist-upgrade
 202  [ Press no when prompted, make sure you are happy with the actions ]
 203  # apt-get -qq --print-uris dist-upgrade > uris
 204  # awk '{print "wget -O " $2 " " $1}' < uris > /disc/wget-script
 205 </example>
 206
 207 Any command other than dist-upgrade could be used here, including
 208 dselect-upgrade.
 209
 210 <p>
 211 The /disc/wget-script file will now contain a list of wget commands to execute
 212 in order to fetch the necessary archives. This script should be run with the
 213 current directory as the disc's mount point so as to save the output on the
 214 disc.
 215
 216 <p>
 217 The remote machine would do something like
 218
 219 <example>
 220   # cd /disc
 221   # sh -x ./wget-script
 222   [ wait.. ]
 223 </example>
 224
 225 Once the archives are downloaded and the disc returned to the Debian machine
 226 installation can proceed using,
 227
 228 <example>
 229   # apt-get -o dir::cache::archives="/disc/" dist-upgrade
 230 </example>
 231
 232 Which will use the already fetched archives on the disc.
 233
 234 </sect>
 235                                                                   <!-- }}} -->
 236 </book>