Linux Server Configuration

1.6 Installation of Software in Linux

There are several different types of installation files for Linux, and few of them are as easy to install as the EXE installation files found on Windows. For Linux we find several different types of files: .deb, .rpm, .bin, .tar.gz, INSTALL, .sh, etc. These different files all have a different method of execution. Below are instructions on installing these filetypes. The following section assumes that we are running Ubuntu Linux system.

1.6.1 Using apt-get

Ubuntu has something called apt-get, which allows you to draw from a set of online repositories (stored in the /etc/apt/sources.list file) that house packages (i.e., programs/software). The apt-get command does several things at once—it downloads the appropriate files, downloads all their dependencies, and installs all of them. A single command installs the software. You don't have to download a separate installer file or unzip or go through a wizard or reboot. For example, if I wanted to install Thunderbird, I'd type these commands in a terminal:
$ sudo apt-get update
$ sudo apt-get install thunderbird
The first command looks both at what I have installed and what's available in the repositories. The second command downloads the packages needed for Thunderbird and installs them.
Another great thing about apt-get is the ability to install several different packages at once. For example, if I wanted to install not only Thunderbird but Firefox, GIMP, Inkscape, Juk, and Wine, I could type in these commands:
$ sudo apt-get update
$ sudo apt-get install thunderbird firefox gimp inkscape juk wine
And all of those packages would download and install themselves.
This is the best way of installing software in Ubuntu because it automatically resolves all dependencies and installs them.

1.6.2 Configuring the sources.list File

The sources.list file resides in the /etc/apt directory. Like most other Linux configuration files, it can be revised by using an ordinary text editor, such as ae.
The file contains a series of lines, each specifying a source for packages. The lines are consulted serially, so it's usually advantageous to place lines that specify local sources - such as a CD-ROM - ahead of lines that specify remote sources. Doing so can save many minutes of download time.
Each line has the form:
deb
uri distribution components
The uri is a universal resource identifier (URI) the specifies the computer on which the packages reside, the location of the packages, and the protocol used for accessing the packages. It has the following form:
protocol://
host/
path
Four protocols - sometimes called URI types - are recognized:

cdrom	A local CD-ROM drive.
file	A directory of the local filesystem.
http	A Web server.
ftp	An FTP server.

The host part of the URI and the preceding pair of slashes (//) are used only for the http and ftp protocols. There, the host part of the URI gives the name of the host that contains the packages.
The path part of the URI always appears, with the preceding slash (/). It specifies the absolute path of the directory that contains the packages.
Here are some examples of typical URIs:
cdrom:/cdrom
cdrom:/mnt/cdrom
file:/mnt
file:/debian
http://www.us.debian.org/debian
http://non-us.debian.org/debian-non-US
ftp://ftp.debian.org/debian
ftp://nonus.debian.org/debian-non-US
The distribution part of a sources.list line specifies the distribution release that contains the packages. Typical values include:

• 
  stable : The latest stable release; that is, one that is commonly regarded as having sufficiently few serious bugs for everyday use.
  

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