When you're done editing in pico, you'll exit it using the following steps.
To Exit pico:
Within pico, press . If you haven't made any changes to the text since you last saved the file, you'll find yourself immediately back at the shell prompt. If you have made changes, you'll be prompted to "Save modified buffer" (Figure 4.10).
Figure 4.10. pico gives you the opportunity to "Save modified buffer." Without the techno-babble, this means to save the text you just wrote or edited before you exit.
At the "Save modified buffer" prompt:
Press if you want to save your changes. Proceed to step 3.
Press if you don't want to save your changes. You'll end up back at the shell prompt.
Specify the filename for your file if it's the first time you've saved it. If you've saved it before, press to confirm the current filename or change the name to save a copy and not change the original file.
A buffer is what the computer uses to temporarily store information, and if it's modified, that means that it's temporarily storing something that you haven't saved to disk.