Emacs

Install

Download Emacs tarball from https://ftp.gnu.org/gnu/emacs/

Extract with

tar zxvf emacs-<version>.tar.gz

Set up install location, the default is /usr/local/

./configure --prefix=/usr/local

Then install with

make && make install

Using PPA (Personal Package Archive)

sudo add-apt-repository ppa:kelleyk/emacs
sudo apt-get update
sudo apt install emacs26

Then delete the repository from /etc/apt/sources.list.d, if you do not trust it.

Install errors

Gnutls not found

apt-cache search libgnutls.*-dev
apt-get install libgnutls.<version>-dev

In case your Emacs icon is missing

sudo gtk-update-icon-cache /usr/share/icons/hicolor

MacOS install

After installing brew,

brew install --cask emacs

Go to Finder > Applications, then right-click Open. Otherwise, you get Apple can't check app for malicious software

If you get the error Opening directory: Operation not permitted, /Users/nalma/Documents/, then give permission to ruby which launches the Emacs.

Basics

Emacs looks for an init file ~/.emacs, ~/.emacs.el and ~/.emacs.d/init.el in that order.

Emacs vs Vim

vi is archaic version of Vim. With Vim you usually edit files and go back to terminal but with Emacs you try to do everything inside it.

There is a compromise called evil-mode which let's you use Vim keybinding.

Notation

Mnemonics - makes sense but kinda horrible

For example, the combination C-n (hold Control and press n) moves cursor to the next line and C-p to the previous line.

• C stand for Control
• M (meta) stands for Alt
• S for Shift
• s for Super or windows

e.g. C-n, C-x C-f, <return>, RET, etc.

You can also have combinations such as C-M-x (hold Control and Alt, then press x).

Note that Emacs will try to map shifted keys to regular keys if they are not bound, so for example M-x and M-X map to the same thing, i.e. execute-extended-command.

C-x C-f is two combinations is sequence, so press C-x first (you will see it minibuffer as C-x-) and then press C-f. DO NOT try to hold Control while trying to press x and f in sequence because it puts too much strain on your fingers and can result in RSI (Repetitive-Strain-Injury) Syndrom. Or even better is to remap frequent keys into dedicated keys or use fewer key strokes.

Movement

cheat sheet at https://www.gnu.org/software/emacs/refcards/pdf/refcard.pdf

• C-n move down a line
• C-p move up a line
• C-f move forward a character
• C-b move backward a character
• C-x C-f find file and open
• C-x d dired or show directory
• C-x b switch buffer in minibuffer
• C-x C-b show buffers
• C-x C-c exit emacs
• C-x C-s save file
• M-x execute command

Learn Emacs using Emacs

• C-h k describe key pressed
• C-h c describe key briefly
• C-h f describe function name
• C-h v describe variable name
• C-h m describe current modes used

Modes to help

• (which-key) show commands for a prefix after a delay

Command line interface

Type either shell for dumb terminal or term which behaves same as regular terminal Note:

• inside term, the prefix command C-x switches to C-c, so to send an actual C-c to the terminal type it twice, i.e. C-c C-c.
• In term-mode, command C-c C-j switches to term-line-mode and you can navigate text with regular key-binds; command C-c C-k switches to term-char-mode which behaves like terminal emulator.
• In order to send escaped characters to term, switch to term-line-mode with C-c C-j then inserted quoted character C-q C-x and switch back to term-char-mode. So now, C-x is sent to the terminal emulator.

Shell mode commands

• M-n (or C-<up>) and M-p (or C-<down>) to cycle next and previous commands
• C-a and C-e go to beggining and end of line
• M-x send-invisible to hide typed text
• M-r (comint-history-isearch-backward-regexp; similar to regular C-r in terminal emulators) search from previous commands
  • After M-r, cycle matches with C-r backward or C-s forward in history
• C-c M-r (comint-previous-matching-input-from-input) search backwards using current prompt string
• C-c C-l create buffer with command per line

Often it is useful to reexecute several successive shell commands that were previously executed in sequence. To do this, first find and reexecute the first command of the sequence. Then type C-c C-x; that will fetch the following command—the one that follows the command you just repeated. Then type <RET> to reexecute this command. You can reexecute several successive commands by typing C-c C-x <RET> over and over.

source: https://www.gnu.org/software/emacs/manual/html_node/emacs/Shell-Ring.html

Anywhere in Emacs

• M-! to execute single shell command
• C-u M-! same as M-! but insert command output at the mark point

Copy and Paste

Usually C-w, M-w and C-y are used for cutting, copying and pasting. Inside a terminal use S-<insert> and C-<inseart> for copying and pasting; the mark can be set with C-<space> albeit being invisible.

Dired (Directory Editor)

Type C-x d to open dired

• d mark for deletion
• x delete all d-marked files and folders
• m mark for copy, move
• u unmark file or folder
• U unmark all
• C copy a file and prompt for new file name
• R rename a file or folder
• + create folder
• Z compress files using gzip; note the old file is renamed to *.gz
• g revert buffer
• < previous directory in a current dired buffer
• > next directory in dired buffer
• ^ go to parent directory

Files

Open find-file by pressing C-x C-f

sudo or TRAMP

UseC-x C-f /sudo:user@localhost:, this is similar to sudo -s function. To mimic su issue command and type C-x C-f /su:root@localhost:/; localhost is synonymous with hostname.

SSH

Syntax /<method>:<user>@<host>:<dir>.

For Linux-based systems, /ssh:user@host:/

On MS Windows, use PuTTY's plink method, /plink:user@host:/path/to/file

Multihop

Incase you need to change user inside remote host then issue C-x C-f /ssh:userA@remoteA|ssh:userB@remoteA:/. The same method can be used to hop from a remote host to another remote host.

Direct shell

default-directory variable dictaces where shell is opened. The following function will prompt for SSH string, e.g. "/ssh:user@host:/".

(defun remote-shell (remote-string)
  (interactive "sRemote:")
  (let ((default-directory remote-string))
    (shell remote-string)))

Config

# ~/.ssh/config

Host goo
     HostName google.ca
     User root

Then type C-x C-f /ssh:goo:/ to get password prompt

Log files

Type M-x and then

• revert-buffer to refresh the contents of current buffer from hard storage
• auto-revert-mode minor mode for automatically reverting a buffer
• auto-revert-tail-mode minor mode for reverting and moving point to end of file

Editing

M-x align-regexp to align columns based on a regex separator

Writing unicode characters

To type unicode characters, the toggle custom input C-\ and type \lambda to get λ.

To find how a unicode can be inserted, hover over it and type C-u C-x =.

Create shortcut

(add-to-list
    'directory-abbrev-alist
    '("^/jou" . "~/mnt/mdbackup/journal" ))

Then type C-x C-f /jou <RET>

Bookmark files

C-x r m mark for bookmark C-x r b prompt for saved bookmarks

MODE LINE - Emacs

Default

cs:ch-fr buffer pos line (major minor)

cs describes character set ch

1. -- unmodified both locally and on disk
2. ** buffer is modified
3. %* READ-ONLY file changed on disk
4. %% READ-ONLY file not changed

ELISP

List is '(a f b), without ' an apostrophe the first atom (indivisible unit in elisp) is treated as a function.

Frequent key-bindings

Arrow keys

Universal across many applications. Having ease access of modifier keys is important.

Troubleshooting

Cannot install packages

if your package expires either disable signature checking

(setq package-check-signature nil)

or install it manually

gpg --homedir ~/.emacs.d/elpa/gnupg --receive-keys 066DAFCB81E42C40

source: http://elpa.gnu.org/packages/gnu-elpa-keyring-update.html