Installing and Updating Software

Package managers are vital for managing software on Linux servers. They help you install, update, and remove applications easily and efficiently.

In this lesson, you'll learn how to use common package manager commands to keep your server's software up-to-date and secure.

Before installing or upgrading software on Debian-based systems (like Ubuntu), it's crucial to update your package lists. This tells your system about the latest available packages and their versions.

Use sudo apt update to refresh these lists from the repositories.

Once your package lists are updated, you can install new software. Let's install cowsay, a fun utility that makes a cow say a message!

The apt install command downloads and installs the specified package and its dependencies.

After updating package lists, you can upgrade your installed software. This downloads and installs newer versions of packages that are already on your system.

sudo apt upgrade only upgrades existing packages; it won't remove or install new ones unless strictly necessary for dependency resolution.

For Red Hat-based systems (like CentOS, Fedora), YUM or DNF are the package managers. DNF is the newer, improved version of YUM.

Unlike APT's two-step `update` then `upgrade`, sudo dnf update (or yum update) typically performs both actions: it checks for updates and then upgrades all installed packages to their latest versions.

Installing software with DNF/YUM is straightforward, similar to APT. Let's install figlet, which creates large character art from ordinary text.

The dnf install (or yum install) command fetches and installs the specified package along with any required dependencies.

When you no longer need a program, you can remove it. For APT, there are two main commands:

• apt remove: Uninstalls the package, but may leave configuration files behind.
• apt purge: Uninstalls the package AND removes its configuration files. This is useful for a clean removal.

Removing software with DNF/YUM is simple. The dnf remove (or yum remove) command uninstalls the specified package.

By default, DNF/YUM aims to clean up configuration files more thoroughly than apt remove, but specific package behavior can vary.

Sometimes you need to upgrade your entire operating system to a new major version (e.g., Ubuntu 20.04 to 22.04). This is different from a regular upgrade.

• APT: Use sudo apt dist-upgrade (after update) and often sudo do-release-upgrade for major version bumps.
• YUM/DNF: Use sudo dnf system-upgrade.

These commands are powerful and should be used with caution, ideally after backing up your data, as they can involve significant system changes.

Which of the following statements about package management commands are true?

You've learned the core commands for managing software on Linux servers!

• APT (Debian/Ubuntu): update (lists), install (new), upgrade (existing), remove/purge (uninstall).
• YUM/DNF (Red Hat/CentOS/Fedora): update (lists & upgrade), install (new), remove (uninstall).

Regularly updating your server's software is a critical practice for security and performance. Keep practicing these commands to master server maintenance!