Updating System Packages

Introduction to Updating System Packages

Welcome to the exciting journey into system automation with shell scripts. As part of our first step, we will delve into the process of updating system packages. We will dive into packages and package managers, then see some practical examples of how to automate keeping your packages up-to-date. Let's get started!

Understanding Packages

Packages are collections of files, metadata, and scripts used to install software on a computer. They bundle all the components necessary to run a program, including binaries, configuration files, documentation, and dependencies. Repositories are structured storage locations from which software packages can be retrieved and installed on your system. They act as central hubs where developers upload their software packages online, and users download them.

Package Managers

In Unix-like operating systems, package management systems (PMS) handle the installation, upgrade, configuration, and removal of these software packages. Advanced Packaging Tool (APT) is a package management system used for handling packages on Debian-based Linux distributions like Ubuntu. apt-get is a command-line tool provided by APT that can be used for handling packages in shell scripts. With this understanding of packages and package managers, let's start writing a script to update them.

Viewing Installed Packages

We can see the list of installed packages by running: Shell apt list --installed apt list --installed The output of this command can be very lengthy (over 300 lines). Let's take a look at a few important lines: text ... bash/focal-updates,focal-security,now 5.0-6ubuntu1.2 amd64 [installed] git/now 1:2.43.0-0ppa1~ubuntu20.04.1 amd64 [installed,upgradable to: 1:2.45.2-0ppa1~ubuntu20.04.1] ... ... bash/focal-updates,focal-security,now 5.0-6ubuntu1.2 amd64 [installed] git/now 1:2.43.0-0ppa1~ubuntu20.04.1 amd64 [installed,upgradable to: 1:2.45.2-0ppa1~ubuntu20.04.1] ... Let's break down the first line: bash : The name of the package. focal-updates,focal-security : The repositories where this version of the package is available now : Indicates the status of the package (currently installed). 5.0-6ubuntu1.2 : The version of the package that is installed. amd64 : The architecture for which the package is built (64-bit in this case). [installed] : Indicates that the package is currently installed on your system. We can see that the bash package is up to date with the version 5.0-6ubuntu1.2 . The git package is currently at version 1:2.43.0..., but we can see it is upgradeable to version 1:2.45.2... .

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Upgrade Package List

The sudo apt-get upgrade command is used to install the latest versions of all installed packages based on the updated package lists fetched by sudo apt-get update. The two main actions of the upgrade command are:

Installs Updates: It fetches and installs the latest versions of the packages installed on your system. This includes all packages for which newer versions are available in the repositories, but it does so without removing any existing packages or installing any new dependencies that might be needed for an upgrade.
Maintains Configuration Files: If any configuration files of the packages have been modified, it will prompt you to decide whether to keep the existing versions or replace them with the newer versions. This helps in maintaining the integrity of your custom configurations.

Upgrading all these packages can take a bit of time. Before actually upgrading your system packages, it might be a good idea to simulate the upgrade to see which packages would be upgraded. Adding the -s option to our command, we can simulate the upgrade command.

Running sudo apt-get -s upgrade, we get an output of 94 packages that can be upgraded. Let's take a look at a small section of the output:

text

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  base-files binutils ... git git-man ...
  .....
94 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Inst base-files [11ubuntu5.7] (11ubuntu5.8 Ubuntu:20.04/focal-updates [amd64])
Conf base-files (11ubuntu5.8 Ubuntu:20.04/focal-updates [amd64])

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  base-files binutils ... git git-man ...
  .....
94 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Inst base-files [11ubuntu5.7] (11ubuntu5.8 Ubuntu:20.04/focal-updates [amd64])
Conf base-files (11ubuntu5.8 Ubuntu:20.04/focal-updates [amd64])

The output informs you that 94 packages, including base-files and git, will be upgraded. Each package shows its current version and the new version that will be installed from the specified repositories.

Let's break down the output

Reading package lists... Done
- This line indicates that apt-get is reading the list of packages from your repositories. This list was previously updated using sudo apt-get update.
Building dependency tree
- This step determines the dependencies of installed packages. A dependency tree is built to understand how packages depend on each other.
Reading state information... Done
- This line confirms that apt-get has read the current state of packages on your system.
Calculating upgrade... Done
- apt-get calculates which packages can and should be upgraded based on the updated package lists.
The following packages will be upgraded:
- This section lists all the packages that have newer versions available and will be upgraded if you run the actual sudo apt-get upgrade command. The packages that will be upgraded are base-files, binutils, git, and so on.

94 upgraded: The total number of packages that will be upgraded.
0 newly installed: Indicates that no new packages will be installed.
0 to remove: Indicates that no packages will be removed.
0 not upgraded: Indicates that there are no packages held back that won't be upgraded.
Inst base-files [11ubuntu5.7]... indicates that the package will be installed or upgraded
Conf base-files (11ubuntu5.8.... indicates that after the package base-files is upgraded, it will be configured to integrate properly with your system.

Introduction to Updating System Packages

Understanding Packages

Package Managers

Viewing Installed Packages

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Updating Package List

Upgrade Package List

Combining All Steps

Summary and Next Steps