Line editing in Bash
You probably know the GNU Bash. Many people would say that it does not have many features or it is even user-unfriendly. I've already tried other POSIX-like shells, but I still stick with my favourite GNU Bash. (I think that fish is quite a good shell, but lacks flexibility of configuration that Bash does have.)
Bash uses the readline library to provide the line-editing features. Readline provides editing of the text you type in, history etc. It has many features, but a lot of them is hidden behind obscure keyboard shortcuts or configuration options.
This page tries to provide an overview of features provided by the readline, especially useful in the Bash. I attempted to order the sections of this page from the most basic operations to more advanced and obscure features.
Few notes
Keyboard shortcuts
We will use three modifier keys: shift, control and alt (also called Meta). I will follow Emacs conventions of keyboard shortcut notation, since this notation is also used by the readline docs and the keyboard shortcuts are significantly influenced by the Emacs. Do not expect CUA-like keyboard shortcuts you know from Windows or many other contemporary desktop environments. The keyboard shortcuts were designed before any common convention was formed.
Notation of keyboard shortcuts I will use:
| Shortcut | Description |
|---|---|
a
|
A single key “a”, without any modifier keys or Caps Lock. |
C-a or ^A
|
Control-a (case-insensitive) |
M-A
|
Meta-a (Alt-a) |
A
|
Uppercase “A” (Shift-a) |
C-A
|
Control-Shift-A (assuming disabled Caps Lock) |
[
|
Also note that the keyboard shortcuts are processed on level of text, not keycodes or even scancodes. This means that your local keyboard mapping and Caps Lock state is applied before the Readline processes the keyboard shortcuts. Also, Control performs bitwise and operation with number 0x1f on the character code, therefore all shortcuts with Control are case-insensitive.
The Meta (Alt) key is usually implemented by prefixing all individual key codes with escape character (^[, 0x1b). When you do not have Alt key or your terminal emulator is broken, you can prefix each of the shortcuts manually with a press of the Escape key. This is useful when using terminal emulators on Android devices, where support of the Alt key is frequently broken or half-functioning.