Emacs: a powerful text editor

On this page

A text editor provides an environment to write and edit plain text files such as source codes. Many would like to use IDEs to write and run source codes. That might be very useful for small programs, but as long as your projects being larger, writing and editing codes with IDEs become a very tedious task. Emacs is one of the best text editors that let us edit and write source codes faster and easier. It might be very challenging to start using any editors like Emacs, but it is definitely worth to spend some time to learn the first steps. This tutorial provides a list of commands, configurations and features that we need to begin.

Installation

To start working Emacs you might need to install it first. To install Emacs follow the instruction at GNU Emacs. Briefly for:

  • Linux (Debian) use sudo apt install emacs
  • Mac use binaries - see config here

Config file

Use a text editor to create Emacs config file called .emacs in the home directory cd ~ then insert the following to make our very preliminary configurations by:

;; Add MELPA
(package-initialize)
(add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t)

;; Personal information
(setq user-full-name "Your Name"
      user-mail-address "your@email.com")

;; Backup in one place
(setq backup-directory-alist '(("" . "~/.emacs.d/backup")))

;; Turn on bracket match highlight
(show-paren-mode 1)

;; Auto insert closing bracket
(electric-pair-mode 1)

Note that we can use (setq make-backup-files nil) and (electric-indent-mode -1) to disable automatic backup and new lines auto-indentation.

Commands

The following are some important commands in Emacs. Note that C and M stand for Ctrl and Alt respectively.

  • C-x C-c: exit
  • C-z: suspend
  • C-k: kill the line
  • C-w: cut the line/text
  • M-w: copy the line/text
  • C-y: uncut/paste the line/text (yank)
  • C-space arrow keys: select text
  • C-shift arrow keys: select paragraphs
  • C-x u: undo
  • C-a: move to the beginning of the line
  • C-e: move to the end of the line
  • M-left: one word left
  • M-right: one word right
  • C-home/M-<: move to the beginning of the buffer
  • C-end/M->: move to the end of the buffer
  • M-g g: go to line
  • C-s/C-r: search/reverse search
  • M-%: replace
  • C-g: stop a command
  • C-x C-f: make/open a file as a new buffer
  • C-x b: change the buffer
  • C-x k: kill the buffer
  • C-x 1: close other windows
  • C-x 0/q: close/quit windows
  • C-x o: switch to other windows
  • C-h ?: help list
  • C-h t: tutorial
  • C-h d: search help for a pattern
  • C-h c: show help for the command
  • M-x <command>: run commands
  • M-x ispell: spell check; enter the suggested digit or a to accept and r to rewrite
  • M-x package-install: install packages
  • M-x package-list-packages: list of packages

You may find more details in:

Customize faces

An easy way to change the appearance of Emacs is changing faces. M-x list-faces-display shows current faces that can be modified (use GUI Emacs to access them by clicking). To customize certain faces, use M-x customize-face and select the face that you want to change (press tab to see all options).

Also, we are able to customize faces from Emacs config file. For instance, adding the following to the .emacs file will change some faces in the Emacs terminal mode:

;; Customize faces
(custom-set-faces
 '(font-lock-builtin-face ((t (:foreground "SkyBlue1"))))
 '(font-lock-comment-delimiter-face ((t (:foreground "salmon"))))
 '(font-lock-comment-face ((t (:foreground "chocolate1" :slant oblique))))
 '(font-lock-constant-face ((t (:foreground "lime green"))))
 '(font-lock-doc-face ((t (:foreground "light coral" :slant oblique))))
 '(font-lock-function-name-face ((t (:foreground "green" :weight bold))))
 '(font-lock-keyword-face ((t (:foreground "SteelBlue1" :weight bold))))
 '(font-lock-preprocessor-face ((t (:foreground "cornflower blue" :slant italic))))
 '(font-lock-regexp-grouping-backslash ((t (:weight bold))))
 '(font-lock-regexp-grouping-construct ((t (:weight bold))))
 '(font-lock-string-face ((t (:foreground "violet" :slant italic))))
 '(font-lock-type-face ((t (:foreground "green" :weight bold))))
 '(font-lock-variable-name-face ((t (:foreground "lime green"))))
 '(font-lock-warning-face ((t (:foreground "dark orange" :weight bold))))
 '(minibuffer-prompt ((t (:foreground "lime green" :weight bold)))))

To change the theme use M-x load-theme, then press tab to see list of the available themes. To unload the theme use, M-x disable-theme. Also, we can set a theme permanently, by adding (load-theme '<theme-name>) to the .emacs init file. For example:

;; Load tango-dark theme
(load-theme 'tango-dark)

Install packages

In Emacs we can install extra packages based on our needs. To install a new package, press M-x and type package-refresh-contents to fetch all packages and then use M-x package-install and enter the new package’s name. For example we can install Markdown-mode, htmlize, ESS (R-mode), autocomplete-mode and Jedi with:

M-x package-install markdown-mode
M-x package-install htmlize
M-x package-install ess
M-x package-install auto-complete
M-x package-install jedi

To see list of the available packages use M-x package-list-packages. And to delete packages, use M-x package-delete and enter the package’s name. Note that you may use C-s / C-r for searching and C-g to cancel any actions and q to close buffers in Emacs.

Org-mode

Org website describes “Org mode is for keeping notes, maintaining TODO lists, planning projects, and authoring documents with a fast and effective plain-text system”. Org-mode in Emacs is very similar to Markdown. They let us combine text and codes and evaluate codes and generate PDF or HTML outputs. Following are great resources to learn Org:

Recent Emacs includes Org mode, to begin, use emacs test.org to create an Org file by Emacs.

Introduction

Let’s learn how use org-mode to:

  • insert headlines M-enter
  • move headlines up and down M-up/down
  • fold/unfold tab/shift-tab
  • insert blocks
    • example blocks <e-tab
    • source code blocks <s-tab
      • for example org/bash/python
  • create tables
  • create TODO items
  • save C-x C-s, export C-c C-e, and exit C-x C-c
    • use C-c C-e and press h and then o to see HTML output

To create above list in Org use:

 ** Introduction
 Let's learn how use *org-mode* to:
 - insert headlines (=M-enter=) - press =M-enter= to go to the next line
 - move headlines up and down (=M-up/down=)
 - fold/unfold (=tab/S-tab=)
 - insert blocks 
   - example blocks (=<e-tab=)
   - source code blocks (=<s-tab=) 
     - for example org/bash/python
 - create tables
 - create TODO items
 - save (=C-x C-s=), export (=C-c C-e=), and exit (=C-x C-c=)
   - use =C-c C-e= and press =h= and then =o= to see HTML output

Use M-up/down to see how easy we can move headlines and use C-c C-e h o to see the outputs in the browser.

Note: unordered lists in Org start with - or + and ordered lists start with a number and a dot and descriptions use ::.

For example, this is an ordered list:

  1. First - press M-enter
  2. Second - press M-enter
  3. Third is a link to org-mode website

To create above list in Org use:

*For example*, this is an /orderd/ list:
 1. First - press =M-enter=
 2. Second - press =M-enter=
 3. Third is a link to [[https://orgmode.org/][org-mode]] website

Tables

The following is table of key abbreviations:

Name key Abbr.
Control Ctrl C
Meta Alt M
Shift Shift S
Return Enter RET 
| Name    | key   | Abbr. |
|---------+-------+-------|
| Control | Ctrl  | C     |
| Meta    | Alt   | M     |
| Shift   | Shift | S     |
| Return  | Enter | RET   |

To create above table in org, we only need to insert |Name|Key|Abbr. and press tab to make new row and insert -tab (i.e. dash tab) to draw the hline and press tab. Also you can use (these might be different in different OS):

  • M-up/down to move rows
  • M-left/right to move columns
  • M-S-up/down to add/remove rows
  • M-S-left/right to add/remove columns

We can use <c>, <l> or <r> for center, left or right alignment.

Basic TODO

To create a TODO list you only need:

 ** TODO learn org-mode
 ** DONE learn emacs
    DEADLINE: <2019-11-16 Sat>

To change a TODO task to DONE or remove it use S-left/right. Use C-c C-d to add a deadline.

LaTeX

We can use LaTeX to write equations in Org. For example:

#+BEGIN_SRC latex
\begin{equation}
x=\sqrt{b}
\end{equation}
If $a^2=b$ and $b=2$, then the solution must be either $$a=+\sqrt{2}$$ or $$a=-\sqrt{2}$$
#+END_SRC

Org processes LaTeX codes in the HTML/PDF outputs.