From Raspberry Pi For Dummies by Sean McManus, Mike Cook
The Raspberry Pi is perhaps the most inspiring computer available today. It comes with the tools you need to start making your own software, and you can connect your own electronic inventions to it. It's different from other computers you've used, however, so it can take a little time to get started with it. These tips show you how to discover and install great free software on your Raspberry Pi and how to fix common problems in your Raspberry Pi setup.
How to Install Games and Other Software on the Raspberry Pi
Lots of free Linux software is available for the Raspberry Pi, and you can install it in two different ways. The most obvious and user-friendly is to use the Pi Store in the desktop environment, but a much wider range of software is available if you use the Linux shell.
Here's how you can find, download, and install software packages using the shell:
1. Log in to your Raspberry Pi, but don't enter the desktop environment.
Alternatively, if you're in the desktop environment, double-click the LXTerminal icon to open a shell session.
2. The first step in installing software is to update the repository, which is the list of packages the package manager knows about. You do that by entering the following command: sudo apt-get update
3. The apt cache contains an index of all the software packages available, and you can search it to find the software you want. For example, you can find all the games by using sudo apt-cache search game | less
From this listing, find a package you want to install. Each line has the name of a package, a hyphen, and then a description of the package.
4. Use the up and down cursor keys (or Page Up and Page Down keys) to move through the list of files. Press Q to finish browsing the list.
In the listing, the bit before the hyphen tells you the name of the package, which is what you need to know to be able to install it. That might not be the same as the game's title or its popular name.
5. When you know the name of the package you would like to install, the following command downloads it from the Internet and installs it, together with any other packages it needs to work correctly (known as dependencies): sudo apt-get install penguinspuzzle.
The last bit (penguinspuzzle) is the name of a package found by searching the cache.
Your software is now installed! You should be able to run it either from the shell by entering its name (for example, penguinspuzzle), or through your Programs menu in the desktop environment.