Datasheet

Part I ✦ The Fundamentals

Package repositories

Package repositories are large archives of packages that are stored, usually on the

Internet, for users to pull from when they want to install or upgrade software on

their system. Though obviously not a part of a package, repositories are neverthe-

less very important to the implementation of package management systems.

Though some package management systems require users to operate directly on

package files themselves, advanced systems keep databases describing the pack-

ages contained in a repository and can pull from them automatically. Not only does

this allow the user to retrieve information with only the package name to work

with, but it also avoids the tedious step of first finding a package file and then

downloading it.

Debian’s package repository contains approximately 15,000 binary packages for

each architecture it supports. The database that describes the packages in this

repository is copied to the user’s machine on a regular basis by the user (in a pro-

cess described later in this chapter). With the database stored locally, package

searches and information retrieval are fast and convenient. The form that a Debian

repository takes varies — for instance, installation CDs are partial repositories.

However, most users prefer using Debian’s Internet servers, which allow the user to

download only those packages they’re interested in (as opposed to either down-

loading all 13 CDs’ worth of packages or purchasing and carrying around a small

library of CDs).

Configuring which Debian repositories to use is as simple as editing

/etc/apt/

sources.list

(type man sources.list for more information on how to do this)

or removing

/etc/apt/sources.list and then running apt-setup.

Package Management Tools

Getting into the meat of package management, this section simply provides an

overview of the various package management tools in Debian. In addition to graphi-

cal front ends and package management systems, there are three main tools that

can be used for different purposes at different times:

✦ The

apt family — Probably the most famous part of Debian, apt-get is a

command-line tool to install and remove packages.

apt-get is part of the apt

family of tools, where apt stands for “advanced package tool.” apt-get’s sim-

plicity is unmatched — to install a package, you issue a command such as

apt-get install packagename. Though it doesn’t provide pretty buttons

and lots of colorful icons,

apt-get is easy to learn and simple to use. Its com-

mand-line nature also allows it to be used remotely over very low-bandwidth

or unreliable connections.

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