LPI Updated 101-500 Exam Questions and Answers by annabel

The /etc/apt/sources.list file is the main configuration file for the Advanced Package Tool (apt), which is used to manage Debian installation package files. This file contains a list of repositories, or sources, from which apt can download and install packages. Each repository is specified by a line that has the following format:

type uri suite [component1] [component2] […]

Where:

• type is the access method, such as http, ftp, file, etc.
• uri is the Uniform Resource Identifier (URI) of the repository, such as http://deb.debian.org/debian
• suite is the distribution code name or archive name, such as stable, testing, unstable, etc.
• component is an optional section of the repository, such as main, contrib, non-free, etc.

For example, a typical sources.list file for Debian stable could look like this:

deb http://deb.debian.org/debian stable main contrib non-free deb-src http://deb.debian.org/debian stable main contrib non-free

deb http://deb.debian.org/debian-security/ stable/updates main contrib non-free deb-src http://deb.debian.org/debian-security/ stable/updates main contrib non-free

deb http://deb.debian.org/debian stable-updates main contrib non-free deb-src http://deb.debian.org/debian stable-updates main contrib non-free

The first two lines specify the main repository for Debian stable, with both binary (deb) and source (deb-src) packages. The next two lines specify the security updates repository for Debian stable, which contains important security fixes. The last two lines specify the stable-updates repository, which contains packages that have been updated after the release of Debian stable.

By editing the /etc/apt/sources.list file, one can select the network locations from which Debian installation package files are loaded. However, it is recommended to use a graphical or command-line tool, such as aptitude or synaptic, to manage the sources.list file, as they can handle the syntax and avoid errors.

References:

• 1, 102.4 Lesson 1
• 2, 102.4 Use Debian package management
• man sources.list

 The command that lists all currently installed packages when using RPM package management is rpm --query --all. This command displays information about all the packages that are currently installed on the system, including their name, version, release, and architecture1. The output can be customized by using various query options and format specifiers2.

The other commands are either invalid or related to YUM, not RPM. yum --query --all is not a valid YUM command, as YUM does not have a --query option3. yum --list --installed is a valid YUM command, but itlists the packages from the YUM repositories, not the RPM database3. rpm --list --installed is not a valid RPM command, as RPM does not have a --list option2.

References:

• RPM Command in Linux | Linuxize
• rpm(8) - Linux manual page
• Linux package management with YUM and RPM | Enable Sysadmin

 The dpkg command is a tool to install, build, remove and manage Debian packages. The option --remove is used to remove an installed package, but it does not remove the configuration files that may have been modified by the user. The option --purge is used to remove an installed package and also delete its configuration files. This can be useful if the user wants to completely uninstall a package and start from scratch if it is reinstalled later. The syntax is: dpkg --remove package or dpkg --purge package. For example, dpkg --remove nginx will remove the nginx web server package, but it will leave the configuration files in /etc/nginxdpkg --purge nginx will remove the nginx package and also delete the configuration files in /etc/nginx1. The other options are not correct because:

• –remove only removes the program, --purge only removes the config files: This is false, because --purge also removes the program, not just the config files.
• –remove removes a package, --purge also removes all packages dependent on it: This is false, because --purge does not remove any other packages, only the specified one. To remove a package and its dependencies, the apt-get command can be used with the option --auto-remove2.
• –remove removes only the package file itself, --purge removes all files related to the package: This is false, because --remove also removes the files that are installed by the package, not just the package file itself. --purge only removes the configuration files that are not removed by --remove. References:
• dpkg(1) — dpkg — Debian buster — Debian Manpages
• How to remove a package and its dependencies with dpkg? - Ask Ubuntu

 The apt-cache command is used to query the APT cache for information about packages. The depends option shows a listing of each dependency a package has and all the possible other packages that can fulfill that dependency. For example, apt-cache depends ubuntu-restricted-extras will show the dependencies of the ubuntu-restricted-extras package. The other options are not valid for the apt-cache command. References:

• How to Check Dependencies of a Package in Ubuntu/Debian-based Linux Distributions
• Check DEB package dependencies on Ubuntu / Debian