CLI Magic: Bash complete (Linux.com)

I am biased since I am the author of fish, but I would say that fish is much more newbie friendly than bash. Newbie friendly touches that fish has that bash lacks include:

• When autocompleting commands, a brief description of what each command does is shown.
• When running inside X, the X clipboard buffer is used for copy and paste operations.
• Syntax highlighting, including coloring many types of errors in red.
• Good error reporting, including actually helpful error messages, stack traces with line numbers and argument lists, and detection of common errors with suggestions on how to fix them.
• 'Universal variables', i.e. variables whose value is shared between all the users fish instances, and which are automatically saved across reboots. This is a very nice way to change configuration options like PAGER without having to edit any files.
• No configuration required, fish comes with a sane default configuration, to use bash at it's best you have to spend a lot of time tweaking your .bashrc file.

Edit ~/.inputrc and add:
set show-all-if-ambiguous on

Mandriva is the only distro I have tried that gets this right. It's far more helpful. And the system-bell is then meaningful on the occasions when it is used. (Redhat,Debian,Ubuntu get it 'wrong').

if using Konsole, you probably want to use the System Bell (= pcspkr) rather than System Notification (= arts)

A potential downside to bash's programmable completion is when a distribution has pre-loaded it with a ton of rules that override normal completion. For example someone has preconfigured a rule so that bash will only complete *.txt files for the command you're trying to run, but the file you want to use doesn't match that pattern. I forget where I ran into this situation, but I've seen it in action and "annoying" doesn't even begin to describe it.

The most interesting auto-completion system I've ever used was rk, the "Reactive Keyboard". This was an add-on that wrapped your shell session and intercepted command-line input. It was useful with e.g. the old Sun csh because it gave you things like a browsable history and emacs bindings. Its big trick, though, is that it could predict what you were going to type next based on prior input. And since it was sitting on top of the entire shell session it actually kept running when you entered other command-line tools such as "ftp" and could then predict your next ftp commands such as "cd pub" or "binary". I recall it being pretty good at the predictive stuff, and very easy to work with.

The downside was that it could end up using several megabytes of RAM to hold the predictive history, and back in those days it really hurt for each shell to be eating 8M.

It was apparently someone's thesis project and there was even a book published about it, but the software pretty much died sometime in the mid-90s. You can still find old versions of the sourcecode lying around if you look really hard, but none of the ones I've seen are Linux-ready.