Useful GNU Readline Settings

I thought I would share some of the settings found in my .inputrc GNU Readline configuration file.

As you’ve already ended up on this page you probably already know what GNU Readline is, but for those who don’t, here’s the one-sentence explanation:

GNU Readline is a software library that provides line-editing and history capabilities for interactive programs with a command-line interface, such as Bash.

Most users come in contact with GNU Readline through the “Bash prompt” or programs like the MySQL shell. Most of the GNU Readline settings can be set in each programs respective configuration file. Like .bashrc. But the .inputrc is specifically for GNU Readline. So the settings there will be inherited by any program that implements GNU Readline. In other words, same settings almost everywhere 🤓.

Settings

set bell-style none

Turns off any annoying beeps bash makes, like the one when you hammer the backspace while you’re at the start of the prompt. No more “ding ding ding” 🙌!

set colored-stats on
set colored-completion-prefix on

The first option, colored-stats, makes your completions colored just like when you ls --color=auto. The second line puts some color on the current prefix used to search possible completions. For example if you type apt- and then hit tab, the apt--part will be highlighted when GNU Readline gives you completion suggestions like apt-get and apt-cache.

set completion-ignore-case on
set completion-map-case on

The first line is self explanatory, it turns off case sensitivity. The second option, completion-map-case isn’t a great label. What it does is to treat hyphens - like underscores _ and vice versa. This option only works when completion-ignore-case is turned on, like above.

set echo-control-characters off

When your timing is off or your brain stops working when jumping around the command line you just throw combinations like Ctrl+C for no reason. And GNU Readline is polite, so it just thinks “what the hell” and echo out your combo 🤜🤜🤛👊🤛🤜. This settings tells GNU Readline that it doesn’t have to bother.

set menu-complete-display-prefix on

When hitting Tab to search possible completions, GNU Readline will show you the common prefix for the possible completions and present them in a list. For example, if I have a package.json file and a package-lock.json file running vi p + Tab will make GNU Readline list the two files and append to your prompt up to vi package. This is because all (both) possible completions share the prefix package.

$if Bash
 Tab: menu-complete
$endif

By default, Bash binds a function called complete to the Tab key. That function show a list of possible completions and completes up to the lowest common prefix. If you keep hammering on the Tab key, just repeats this action. With Tab bound to menu-complete. Bash will cycle through the options as you keep hammering the Tab key, much better! There’s also menu-complete-backwards, hmm?? 🤔😉

There’s more

If you’re using the GNU Readline (command line) a lot and want to tweak and bend it. Fire up a terminal emulator and man readline.

Hope you had a nice read and you learned something. Bye. 👋