When working in the shell on a terminal window, I have no problem using th left or right arrow keys, but when I use the up arrow key the most recent shell command is disaplayed at the prompt and so forth. When I press the down arrow, nothing happens at all. How can I remedy this situation?

Have a look at the file ~/.bash_history - it keeps a record of all your commands, so that you can navigate back through them. These are available and are very useful. If you press up, you can navigate through the history. If you press down, well there's no history to navigate through!!

Here's a hint for using the bash more efficiently - lets say the last time you typed

modprobe qcamvc

yesterday some time and it inserted the driver using the modprobe command. If you press

!modp

today, the shell will look back through the ~/.bash_history file to find the most recent incidence of 'modp' and executes that command. Clever, eh?