Managing Software

Introduction

Many modern Linux distributions offer some kind of package manager to install, manage, and remove software. These package management systems interact with curated and audited central repositories of software that are collected into packages. They also provide a set of tools to learn about the software that exists in these repositories.

If package management seems like an odd concept to you, it's just a way to manage software installation, and it's very similar to the way that Apple and Google distribute software via the App Store and Google Play.

On Debian based systems, which includes Ubuntu, we use apt, apt-get, and apt-cache to manage most software installations. For most cases, you will simply want to use the apt command, as it is meant to combine the functionality commonly used with apt-get and apt-cache.

We can also install software from source code or from pre-built binaries. On Debian and Ubuntu, for example, we might want to install (if we trust it) pre-build binaries distributed on the internet as .deb files. These are comparable to .dmg files for macOS and to .exe files for Windows. When installing .deb files, though, we need to use the dpkg command.

Installing software from source code often involves compiling the software. It's usually not difficult to install software this way, but it can become complicated to manage software that's installed from source code simply because it means managing dependencies and keeping a close eye on new versions of the software.

Another way to install software (I know, there's a lot) is to use the snap command. This is a newer way of packaging programs that involves packaging all of a program and all of its dependencies into a single container. The main point of snap seems to be aimed at IoT and embedded devices, but it's perfectly usable and preferable (in some scenarios) on the desktop because the general aim is end users and not system administrators. See the snap store for examples.

You might also want to know that some programming languages provide their own mechanisms to install packages. In many cases, these packages may be installed with the apt command, but the packages that apt will install tend to be older (but more stable) than the packages that a programming language will install. For example, Python has the pip or pip3 command to install and remove Python libraries. The R programming language has the install.packages(), remove.packages(), and the update.packages() commands to install R libraries.

Despite all these ways to install, manage, remove, and update software, we will focus on using the apt command, which is pretty straightforward.

APT

Let's look at the basic apt commands.

apt update

Before installing any software, we need to update the index of packages that are available for the system.

sudo apt update

apt upgrade

The above command will also state if there is software on the system that is ready for an upgrade. If any upgrades are available, we run the following command:

sudo apt upgrade

We may know a package's name when we're ready to install it, but we also may not. To search for a package, we use the following syntax:

apt search [package-name]

Package names will never have spaces between words. Rather, if a package name has more than one word, each word will be separated by a hyphen.

In practice, say I'm curious if there are any console based games:

apt search ncurses game

I added ncurses to my search query because the ncurses library is often used to create console-based applications.

apt show

The above command returned a lit that included a game called ninvaders, which seems to be a console-based Space Invaders like game. To get additional information about this package, we use the apt show [package-name] command:

apt show ninvaders

apt install

It's quite simple to install the package called ninvaders:

sudo apt install ninvaders

apt remove or apt purge

To remove an installed package, we can use either the apt remove or the apt purge commands. Sometimes when a program is installed, configuration files get installed with it in the /etc directory. The apt purge command will remove those configuration files but the apt remove command will not. Both commands are offered because sometimes it is useful to keep those configuration files.

apt remove ninvaders

Or:

apt purge ninvaders

apt autoremove

All big software requires other software to run. This other software are called dependencies. The apt show [package-name] command will list a program's dependencies. However, when we remove software with the prior two commands, the dependencies, even if no longer needed, are not necessarily removed. To remove them, (which restores more disk space) we do:

sudo apt autoremove

apt history

Unfortunately, the apt command does not provide a way to get a history of how it's been used on a system, but a log of its activity is kept. We can review that log with the following command:

less /var/log/apt/history.log

Daily Usage

This all may seem complicated, but it's really not. For example, to keep my systems updated, I run the following two commands on a daily or near daily basis:

apt update
sudo apt upgrade

Conclusion

There are a variety of ways to install software on a Linux or Ubuntu system. The common way to do it on Ubuntu is to use the apt command, which was covered in this section.

We'll come back to this command often because we'll soon install and setup a complete LAMP (Linux, Aapache, MariaDB, and PHP) server. Until then, I encourage you to read through the manual page for apt:

man apt