The Linux CLI for Beginners, or, Fear Not the Linux Command Line!
Please Meet the Linux TerminalMost recent converts to Linux spend most of their time in the GUI -- the graphical desktop (whether Gnome, or KDE, or XFCE, or some other interface) that's made to look and act somewhat like Windows and Mac.
But if you spend all your time in the GUI, you're missing out. The Linux command-line gives you a lot of power -- it lets you do tasks that are difficult or impossible with the GUI, and for tasks that you do a lot, such as launching the same applications everyday, it's often faster. When you read about using the command line, which is often abbreviated to CLI for "command-line interface", they usually mean typing commands into a terminal. This is a term leftover from the olden days of interfacing with mainframes via dumb terminals which had no processing power of their own; they were pretty much just monitors and keyboards. When we refer to a Linux terminal it's a software application, and if you want to get technical it's a terminal emulator.
Wading through all those menus to launch our terminal is tedious, so our first step in learning mighty command-line powers is a fast keyboard shortcut for opening a "run command" dialog. This way we can quickly type in the name of an application to start it. Press the Alt and F2 keys at the same time, and on KDE you see something like Figure 1. Gnome calls it "run application" and it looks similar, with one very nice addition-- an alphabetical graphical menu to browse. On KDE type in konsole and press Run, and in Gnome type terminal or gnome-terminal and press Run. Lo and behold, your shiny terminal opens before you, just like Figure 2 shows.
What you see displayed in the terminal is the command prompt, in this example carla@xena:~$. This tells you the name of the user, the name of their computer, ~ means the current directory is Carla's home directory, and $ means ordinary, unprivileged user. When you see # that means all-powerful root user.