The Pi runs a Linux operating system and if you're not familiar with Linux then the following notes might help. If you're a regular Linux user, then skip this page of notes.
The vast majority of computers in the world run a Unix system of some kind, and these days a substantial proportion of those run Linux. All of the world's top 500 biggest supercomputers run Linux operating systems, virtually all of the world's Internet backbone and servers runs on Linux, most large enterprises have their mission-critical systems running Unix or Linux. Serious workstations for scientific and engineering applications usually run Linux and the majority of your domestic gadgets, phones, routers, satellite receivers, PVRs, and so on, these days run some version of Linux or Unix-like system.
The reason for this is that Unix and Linux are basically very simple and solid operating systems, and immensely powerful and robust too - it will run for years if you can keep the power applied. The workstation I'm typing on has not been rebooted for 508 days (since the last power cut) and I have (quick count) just now 178 windows open, all doing various things, with 614 processes in the process table. During a working week there will be well over 200 windows on my graphical desktop. The X-Windows graphical user interface is powerful enough to easily support than many windows, it is slick to use and simple to program, and general purpose. It is not surprising that the wonderfully successful rockets launched by SpaceX use Linux for their on-board flight control computers. In fact, SpaceX use Linux for just about everything related to their operations.
With that in mind, it's probably well worth getting to know it a little.
You can be confident that whatever you learn to do on a toy computer like the Raspberry Pi, you can also do when you next log into a Cray XC, or telnet into your satellite box, or run up a 128 core VM with 3900 Gbyte RAM on AWS EC2.
One of the many appealing things about Linux and Unix in general, is that nothing is hidden from you. You're not treated like a dumb user restricted to just pushing buttons. Everything is exposed for you to examine and customise. You are given complete control over the machine and you are limited only by your imagination and ingenuity. This can be quite intimidating at first encounter!
With that in mind, I've spelled out all the installation and set up instructions for the Pi and its radio software, so that you can work through it and get to see how it works internally. I could instead have just provided a pre-configured operating system which you can just plug in and run. But then it would be just a black box to you and you would lose out on the major benefit of this operating system - the ability to dig into it, get to see how things work, and modify it to the limit of your imagination.
Most of the installation and programming of Linux is done using commands given to a shell prompt, and by editing configuration files and scripts. In that way, all of the power of the system is handed to you. Linux commands are like a toolkit - you're expected to string the tools (commands) together to make it do what you want. There are a couple of thousand commands at your disposal but only a dozen or so you remember because you use them every day. Fortunately all the commands are documented by 'man' pages which describe how to use them. For example to find out how to use the command 'ls', run
man ls
If you enjoy inventing things with Lego or Meccano, then you'll be a natural with Linux. As soon as you start stringing commands together, you realise that you are programming the computer, not just pressing a button that someone else provided. Linux completely blurs the distinction between user and programmer and that is a good thing - it empowers the user like no other operating system.
The notes on how to set up the Pi and use the radio software include a lot of examples of command lines. Where possible, save typing and ensure accuracy by copying and pasting from the notes into the command prompt or editor. Take a bit of time to look up the commands using the 'man pages' to see what else they can do. Use the up arrow to step back through recent commands if you need to repeat something.
Frequently used sequences of commands can by typed into a file, the file made executable, and then you have another command at your disposal. In this way you build up your own toolkit of commands for your regular use. You'll find there is a lot less typing than you might at first imagine.
A good tip is to keep a text file called 'notes' open in a text editor while you're working. Any command lines that you find useful, just copy and paste them into 'notes' so that you can find and reuse them again easily later. I use lots of notes files: I have a notes-vlf open when I'm working on VLF things, a notes-gps when tinkering with GPS, and notes-ebnaut, notes-rp, notes-dvd, notes-scard, and so on. If I want to recall and reuse the command I used to decode a particular ebnaut message a year ago, it will be in notes-ebnaut and the command 'grep' or a search in the editor will find it for me quickly. I just noticed I've got 91 notes- files, people think I've got a good memory but really it is the notes files!
The usual editor on Unix/Linux is called 'vi' and it is very powerful. There is also 'emacs' which some obscure devotees prefer to use. Both are quite frightening for a novice to use. There is a simple editor called 'nano' which is more like a conventional editor. It works intuitively like any other basic text editor. To edit a file called, say, /etc/dhcpcd.conf, you just run
nano /etc/dhcpcd.conf
at the command prompt. Do your edits and press control-X to exit, then press 'Y' to save, then ENTER to confirm the filename. Maybe you'll want to try vi at some point. It'll take you a few weeks to get up to speed, and then you'll never want to use any other editor again.
There's a tendency amongst Windows users these days to use spaces in filenames. This is never done on Unix/Linux because a space means something to the shell: it separates the components of a command line. So never use spaces. Instead use underscores or dashes or dots to break up a long file name if you have to.
Windows filenames always end with a dot and a three letter extension. This is not the case on Unix/Linux: there is no meaning to the 'extension' of the filename, if indeed there is one. Whereas Windows uses the extension to indicate the type of file, Linux looks inside the file to see what it is. So if you name a binary executable file as something.jpg, it will still be treated as a binary executable file, not an image file. Such devious naming would confuse you, but not the operating system! That means that you can put dots in filenames wherever you like, and you can just invent your own 'extensions' if you want to.
And of course, the slashes in pathnames slant in the right direction! Every where and every thing uses forward slashes except for DOS and Windows. That annoying anomaly is a legacy of an unfortunate decision which IBM made a few decades ago.
Oh, Linux/Unix doesn't use drive letters. Instead, all the disks on your computer (and networked drives from other systems) are joined together into a single tree-structured filesystem. Your primary disk provides the root of the tree and all the other drives are grafted on at convenient places in the tree. A large system might have dozens of drives 'mounted' on the tree.
Just to keep things uniform and simple, devices appear as files in the filesystem, usually somewhere under /dev. So you read and write a device just as you would a file.