Did you know Bash has got macros, a multi-clipboard, an undo feature, and a word completion based on history?

If you prefer watching videos to reading posts, you can check it out here.

For those unfamiliar with Emacs, it’s worth mentioning that the vast majority of these shortcuts are identical to the Emacs shortcuts for the same operations.

So if you’re an emacser most of your muscle memory will work on the shell. Alternatively, if you don’t use Emacs but learn these shortcuts on the shell, you might find yourself right at home in Emacs later on. (via u/alraban)

Legenda

Everywhere, Esc can be used instead of Alt.

Expand

This is a surprisignly unknown, pretty neat feature: it takes whatever is in the line, it evaluates it and it finally inserts the result inline.

You can expand variables such as $PATH and $HOME (try with $RANDOM).

Here are some sleek ideas for using it:

Interestingly, it also works with commands. Try it with $(ls).
I often use it with $(grep whatever /some/place): it performs the search, and then it kindly delivers the result right in the line, ready for me to operate on. How cool.

Indulge with your fantasy and you will appreciate how powerful this little gem is

(History-based) Intellisense

Once this functionality is enabled adding

"\e/": dabbrev-expand

in ~/.inputrc, it is like having a little magic auto-completion tool at your fingertips: it completes any partially input word, based on all the previously input text stored in the command history.

Undo

Bash has got an undo feature. While not as powerful as those in Emacs and Vim (e.g. it can only revert actions, there is no redo command), it is still handy. Curiously, there are 3 keybindings to activate it: C-/, C-_ or C-x C-u. On the US layout, C-/ is the most convenient, as it requires only 2 keys.

Revert line

There is a special version of undo called revert-line. It comes in handy all the times you mess up with a line retrieved from the command history, and you wish to revert it back to its original value.

Macros

Macros are just the coolest, right? If you’re already into Emacs or Vim, you know what I mean. If you’re on VS Code, well, it’s time to branch out and give those editors a try: you won’t regret it.

In the meanwhile, you might be surprised to know that Bash does support macros. Not perfectly, but decently.

Open line in editor

Bash’s macros are cool, but they leave a little to be desired. For example, they cannot capture character-search. Also, Bash’s Vim emulation is remarkable, but your NeoVim and Doom are another level.

Well, if Bash will not go to the mountain, the mountain must come to Bash.
Press C-x C-e and quickly open the current line in Emacs your preferred editor.

Define VISUAL=<your-editor> in .bashrc to select which editor to use

Digit argument

You can repeat any command prefixing it with Alt` followed by the desidered multiplication factor. This works for most the commands.

Actually, this is a way to pass a numeric argument to the subsequent command. In practice, almost all the commands interprets a numeric argument as the number times they should repeat.

Negative argument

You might wonder what happens providing a command with a negative argument. In many cases, this would invert the result.

• If M-d deletes the next word, M-- M-d deletes the previous word;
• C-k deletes from cursor to the end of line; M-- C-k deletes from cursor to the beginning of line (not so handy, though: the shorter C-u does the same)
• C-r searches for a string on the left of cursor; M-- C-r searches on the right

I often use M-- M-u to upcase the word I just typed.

Character Inline Search

Move around faster, searching back and forth for the occurrences of a specified character on the current line.

Use C-] for searching forward, add Alt` for inverting the direction.

If you are a Vim or an Emacs user, you might wonder how you could live in Bash without this functionality since now.

String Inline Search

C-r is widely known for searching the command history, but few know that the same shortcut, when used in a not empty line, searches in that line. C-r searches backword. Of course, prefixing it with a Negative Argument will switch to forward search.

Notice: conclude your search with C-j: hitting Return will also execute the line, which is not necessarily your desidered outcome.

Instant Comment

One of my preferred Zsh’s shortcuts is ESC q. How many times have I written a longhty command line, only to discover I could not run it, because I was in the wrong directory, or because I forgot to run some other command beforehand? ESC q always came to rescue, providing an instant new empty line, and restoring the suspended one right after execution.

Bash does not have ESC q. The related M-# (insert-comment) is not exactly the same, but it can be used in similar situations.

Clipboard

Bash’s support for the clipboard packs a punch in terms of power. In many editors, the selection is defined holding down the Shift key and using the cursor keys. In Bash, just like in Vim and Emacs, you instead define the selection placing 2 handles to mark its beginning and end. The handles can be moved independently, and their position can be adjusted applying whatever movement command, including character and string search, not only using the cursor keys.

Oddly, though, the selection is usually not visible (it is in Zsh).

Notice that the Bash clipboard is a multi-clipboard: it keeps a history of the copied texts enabling you to easily cycle (using M-y) it when it’s time to paste.

Be aware that (copy-region-as-kill) and (kill-region) must be enabled adding:

"\ew": copy-region-as-kill
"\C-w": kill-region

to ~/.inputrc.

Special paste options

Paste last argument

Paste n-th argunent

Deleting

Transforming words

Swapping chars and words

| Shortcut | Command | Description | |———-|———————|——————————————————-| | C-t | (transpose-chars) | swaps the char on the left with the char on the right | | M-t | (transpose-words) | swaps the word on the left with the word on the right |

Changing the case

Suspending a stream

Try to use it while streaming the output of tail -f.

A faster clear

A faster and more aggressive clear

History

Literal chars

I’m still figuring out what is the use, honestly.

Return

Aborting line

C-c is usually used to stop the execution of a command. Few know that it can also be used to quickly cancel and abandon the line being edited.

Quitting

This saves you from writing exit.

Other bindings

There are many other default keybindings which I did not cover here, and even more commands that have no keybindings and can be potentially activated.

Display all of them with:

bind -P

You will get a long list like:

# abort (not bound)
"\C-j": accept-line
"\C-m": accept-line
# alias-expand-line (not bound)
# arrow-key-prefix (not bound)
# backward-byte (not bound)
"\eOD": backward-char
"\e[D": backward-char
"\C-h": backward-delete-char
"\C-?": backward-delete-char

Refer to the Bash and the Readline man pages for more info.

Readline

Many of these funtionalities come from GNU Readline, a library created in the late 1980s by [Brian Fox, the same author of Bash. Over the years, readline has become vastly used in a lot of command-line tools such as Tmux, MySQL and Python. So, those keybindings are almost ubiquitous. Even the GUI text fields in macOS, such as the address bar in browsers, use a Readline-like library, libedit, which is based on the Readline’s code. No surprises that some of the shortcuts above work everywhere in macOS.

Zsh, instead, does not depend on readline, and implemented a line-editing library from the scratch.

You can find the complete list of commands and features supported Readline in readline(3).

Summary

References

• GNU Readline
  • man page
• Bash manpage
• Brian Fox
• Python readline
• Lesser Known Bash Shortcuts - YouTube Video

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