Using APT Offline
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Jason Gunthorpe
<jgg@debian.org>
Version 2.4.14
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Copyright © 1999 Jason Gunthorpe
License Notice
"APT" and this document are free software; you can redistribute them and/
or modify them under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
For more details, on Debian systems, see the file /usr/share/
common-licenses/GPL for the full license.
Abstract
This document describes how to use APT in a non-networked environment,
specifically a 'sneaker-net' approach for performing upgrades.
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Table of Contents
1. Introduction
1.1. Overview
2. Using APT on both machines
2.1. Overview
2.2. The configuration file
3. Using APT and wget
3.1. Overview
3.2. Operation
Chapter 1. Introduction
Table of Contents
1.1. Overview
1.1. Overview
Normally APT requires direct access to a Debian archive, either from a
local media or through a network. Another common complaint is that a
Debian machine is on a slow link, such as a modem and another machine has
a very fast connection but they are physically distant.
The solution to this is to use large removable media such as a Zip disc
or a SuperDisk disc. These discs are not large enough to store the entire
Debian archive but can easily fit a subset large enough for most users.
The idea is to use APT to generate a list of packages that are required
and then fetch them onto the disc using another machine with good
connectivity. It is even possible to use another Debian machine with APT
or to use a completely different OS and a download tool like wget. Let
remote host mean the machine downloading the packages, and target host
the one with bad or no connection.
This is achieved by creatively manipulating the APT configuration file.
The essential premise to tell APT to look on a disc for it's archive
files. Note that the disc should be formatted with a filesystem that can
handle long file names such as ext2, fat32 or vfat.
Chapter 2. Using APT on both machines
Table of Contents
2.1. Overview
2.2. The configuration file
2.1. Overview
APT being available on both machines gives the simplest configuration.
The basic idea is to place a copy of the status file on the disc and use
the remote machine to fetch the latest package files and decide which
packages to download. The disk directory structure should look like:
/disc/
archives/
partial/
lists/
partial/
status
sources.list
apt.conf
2.2. The configuration file
The configuration file should tell APT to store its files on the disc and
to use the configuration files on the disc as well. The sources.list
should contain the proper sites that you wish to use from the remote
machine, and the status file should be a copy of /var/lib/dpkg/status
from the target host. Please note, if you are using a local archive you
must use copy URIs, the syntax is identical to file URIs.
apt.conf must contain the necessary information to make APT use the disc:
APT
{
/* This is not necessary if the two machines are the same arch, it tells
the remote APT what architecture the target machine is */
Architecture "i386";
Get::Download-Only "true";
};
Dir
{
/* Use the disc for state information and redirect the status file from
the /var/lib/dpkg default */
State "/disc/";
State::status "status";
// Binary caches will be stored locally
Cache::archives "/disc/archives/";
Cache "/tmp/";
// Location of the source list.
Etc "/disc/";
};
More details can be seen by examining the apt.conf man page and the
sample configuration file in /usr/share/doc/apt/examples/apt.conf.
On the target machine the first thing to do is mount the disc and copy /
var/lib/dpkg/status to it. You will also need to create the directories
outlined in the Overview, archives/partial/ and lists/partial/. Then take
the disc to the remote machine and configure the sources.list. On the
remote machine execute the following:
# export APT_CONFIG="/disc/apt.conf"
# apt-get update
[ APT fetches the package files ]
# apt-get dist-upgrade
[ APT fetches all the packages needed to upgrade the target machine ]
The dist-upgrade command can be replaced with any other standard APT
commands, particularly dselect-upgrade. You can even use an APT front end
such as dselect. However this presents a problem in communicating your
selections back to the local computer.
Now the disc contains all of the index files and archives needed to
upgrade the target machine. Take the disc back and run:
# export APT_CONFIG="/disc/apt.conf"
# apt-get check
[ APT generates a local copy of the cache files ]
# apt-get --no-d -o dir::state::status=/var/lib/dpkg/status dist-upgrade
[ Or any other APT command ]
It is necessary for proper function to re-specify the status file to be
the local one. This is very important!
If you are using dselect you can do the very risky operation of copying
disc/status to /var/lib/dpkg/status so that any selections you made on
the remote machine are updated. I highly recommend that people only make
selections on the local machine - but this may not always be possible. DO
NOT copy the status file if dpkg or APT have been run in the mean time!!
Chapter 3. Using APT and wget
Table of Contents
3.1. Overview
3.2. Operation
3.1. Overview
wget is a popular and portable download tool that can run on nearly any
machine. Unlike the method above this requires that the Debian machine
already has a list of available packages.
The basic idea is to create a disc that has only the archive files
downloaded from the remote site. This is done by using the --print-uris
option to apt-get and then preparing a wget script to actually fetch the
packages.
3.2. Operation
Unlike the previous technique no special configuration files are
required. We merely use the standard APT commands to generate the file
list.
# apt-get dist-upgrade
[ Press no when prompted, make sure you are happy with the actions ]
# apt-get -qq --print-uris dist-upgrade > uris
# awk '{print "wget -O " $2 " " $1}' < uris > /disc/wget-script
Any command other than dist-upgrade could be used here, including
dselect-upgrade.
The /disc/wget-script file will now contain a list of wget commands to
execute in order to fetch the necessary archives. This script should be
run with the current directory as the disc's mount point so as to save
the output on the disc.
The remote machine would do something like
# cd /disc
# sh -x ./wget-script
[ wait.. ]
Once the archives are downloaded and the disc returned to the Debian
machine installation can proceed using,
# apt-get -o dir::cache::archives="/disc/" dist-upgrade
Which will use the already fetched archives on the disc.
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