Something a bit different this week. Working with various different codes in various different languages, along with writing presentations, talks and papers, I spend most of my day writing text, just with different syntaxes. As such, I like to be able to do it all in the same program – and that program is Emacs. This week, I led another hands-on session, giving a shallow dive into the wide, wide waters of Emacs.

You can get the .el files that accompany this seminar here.

Overview

Terminology/anatomy
Basic commands
Basic customisation
Multiple cursors
Flyspell
Helm
Projectile
LaTeX
C/C++/Fortran (subword mode)
Python

Why Emacs?

It’s the best

Terminology/anatomy

Emacs development began in 1970s, before Windows/MS Office
Names of things can be a little different
Shortcuts for copy, paste, etc. very different
Helps to see original keyboard:

Space-cadet

By Retro-Computing Society of Rhode Island - Own work, CC BY-SA 3.0

Terminology/anatomy

“kill” = “cut”
“yank” = “paste”

Windows and frames

Cpp_in_GNU_emacs

By Original uploaded by: Praveep - Transferred from ml.wikipedia to Commons by Sreejithk2000 using CommonsHelper., GPL

Terminology/anatomy

Major Modes

Only one per buffer
Specialised behaviour for particular file or buffer types
- e.g. C source code, or compilation buffer

Minor modes

Optional features, can have multiple per buffer
- e.g. auto-fill mode for automatically inserting line breaks, or flyspell mode for spell-checking
Some are “buffer-local”, i.e. can be turned on/off per buffer
Some are “global”, i.e. turned on/off for all buffers at once

Vim Users

Evil mode (extensible vi layer for Emacs)
Spacemacs
Doom

Basic commands

C means Ctrl, M means Alt (Meta)
In terminals, C-M- combos might be hard to type, so you can use C-[ C- instead
Lots of commands can take a “prefix argument”: press C-u before the rest of the shortcut or command to use optional arguments
- e.g. C-u 4 C-b: move four characters backwards
Rebinding Caps lock as an extra ctrl can be useful: https://www.emacswiki.org/emacs/MovingTheCtrlKey
Eval any elisp commands anywhere with C-x C-e
C-g: general purpose “cancel”

Movement you might not know

Lines

M-m: move to first non-whitespace character on line

Brackets

C-M-f, C-M-b: move over balanced brackets
C-M-<space>: selected balanced brackets

Functions

C-M-a, C-M-e: move over functions
C-M-h: select whole function

Getting help

Help functions

C-h f help on functions
C-h v help on variables
C-h l key stroke history (possibly with command names!)
C-h m help on current major mode (keybindings and useful functions)

Outside Emacs:

https://emacs.stackexchange.com/ Q&A site
https://www.emacswiki.org/ Generally good first stop
https://tuhdo.github.io/ In-depth tutorial

Beyond the basics

Macros

C-x ( Begin record macro
C-x ) End recording
C-x e Run macro
C-u <n> C-x e Run macro <n> times
M-0 C-x e Run macro until it stops

Beyond the basics

Rectangles

C-x r k: kill rectangle
C-x r y: yank rectangle
C-x r t: replace rectangle with string
C-x r N: insert numbers in front of rectangle

Capitalisation

M-u: UPPERCASE next word
M-l: lowercase next word
M-c: Capitalise next word

Beyond the basics

Working with windows

C-x 2: Split window vertically
C-x 3: Split window horizontally
C-x 0: Close this window
C-x 1: Close everything but this window
C-x C-b: List of open buffers
C-x 4 b: Switch to buffer in other window

Beyond the basics

Miscellaneous

M-q: “fill” paragraph - insert line breaks at “fill-column”
M-<space>: replace multiple whitespace with single space
M-$: spell-check word
M-/: auto complete

Beyond the basics

emacsclient

In bash, set the environment variable EDITOR to emacsclient, and do M-x server-start inside an existing emacs session
Now when other programs need to open $EDITOR, it will open in your existing emacs session

TRAMP

Open remote files by prepending the path with /ssh:username@host:

Basic customisation

Emacs core is written in C, but wrapped in elisp (Emacs Lisp)
All customisation is done through elisp
Key points about elisp:
- Functions are written in Polish notation with function name first, then arguments: + 1 2
- Everything is written in a list: (+ 1 2)
- Code and data are treated as equals, which means we often need to distinguish between symbols and their values: use (quote x), or simply 'x

Basic customisation

`customisations/0-basic.el`

;; Remember minibuffer history across sessions:
(savehist-mode 1)

;; Remember lots of history lines:
(setq history-length 100)

;; No startup screen
(setq inhibit-startup-screen t)

;; Highlight region
(transient-mark-mode 1)

Installing packages

`customisations/1-packages.el`

;; We need symbols from the "package" package
(require 'package)

;; Use https for packages
(setq package-archives
      '(("gnu" . "https://elpa.gnu.org/packages/")
        ("melpa" . "https://melpa.org/packages/")))
;; Do some basic hardening of the package system
;; See https://glyph.twistedmatrix.com/2015/11/editor-malware.html

Use use-package

https://github.com/jwiegley/use-package

`customisations/1-packages.el`

;; Initialise packages now
(setq package-enable-at-startup nil)
(package-initialize)

;; Make sure we have use-package installed
(unless (package-installed-p 'use-package)
  (package-refresh-contents)
  (package-install 'use-package))

(eval-when-compile
  (require 'use-package))
(require 'diminish)
(require 'bind-key)

Magit

https://magit.vc/

The best git interface

Needs Emacs 24.4+ (not available in Ubuntu 14.04) and git 1.9+

`customisations/2-magit.el`

(use-package magit
  :ensure t
  :bind
  (("\C-cm" . magit-status)))

Multiple cursors

https://github.com/magnars/multiple-cursors.el

`customisations/multiple-cursors.el`

(use-package multiple-cursors
  :bind
  (("C->" . mc/mark-next-like-this)
   ("C-<" . mc/mark-previous-like-this)))

Auctex

https://www.gnu.org/software/auctex/

`customisations/3-auctex.el`

(use-package tex
  :ensure auctex

  :config
  (setq TeX-auto-save t
        TeX-parse-self t
        TeX-PDF-mode t)
  (setq-default TeX-master nil)
  (add-hook 'LaTeX-mode-hook 'turn-on-reftex))

Auctex

Basic commands

C-c RET: insert macro
C-c C-e: insert environment
C-u C-c C-e: change environment
C-c C-c: run LaTeX/BibTex/View document

C/C++/Fortran

Example C project

Open c/main.c
M-x shell to get an Emacs shell
make tags to run etags and make TAGS file

xref

M-.: Find definition
M-?: Find reference
M-,: Go back

C/C++/Fortran

Compiling

M-x compile: Compile the code
C-x `: Jump to first error

See customisations/4-c-like-languages.el for some more useful things

Helm (previously Anything)

https://github.com/emacs-helm/helm

`customisations/5-helm-projectile.el`

(use-package helm
  :ensure t
  :diminish helm-mode
  :bind
  (("C-x C-f" . helm-find-files)
   ("M-x" . helm-M-x)
   ("M-y" . helm-show-kill-ring)
   ("C-x b" . helm-mini)
   ("C-c h" . helm-command-prefix))

  :config
  (helm-mode 1))

Helm

Better completion of commands
http://tuhdo.github.io/helm-intro.html

General use

Search for candidates by typing parts (or regex) of match:
- e.g. “li pa” brings up list-packages
- e.g. “.*[ch]xx” brings up all C++ files
You can run actions on candidates, e.g. bring up the help on a function
You can mark multiple candidates and run an action on all of them
- e.g. close multiple buffers

Helm

Useful actions

C-x b can show recent buffers by pressing $\rightarrow$
In buffer menu, M-S-d (M-D) to kill buffer(s)
In file/buffer menu, C-o to open in other window
In file menu, C-l to go up a level
In function/variable help menu, <tab> to display help for highlighted function
In any helm menu, C-h m to get more help

Projectile

http://batsov.com/projectile/

`customisations/5-helm-projectile.el`

(use-package projectile
  :ensure t
  :init
  (projectile-mode t)
  (use-package helm-projectile)
  (setq projectile-completion-system 'helm)
  (helm-projectile-on))

All-in-one command: C-c p h
- Switch to buffer
- Find file
- Switch project

Back to C project

https://tuhdo.github.io/helm-projectile.html

Projectile commands

C-c p a: Switch to “other” file (.c <--> .h)
C-c p c: Run compile command
C-c p P: Run test command
C-c p s g: Run grep on project

Python

https://elpy.readthedocs.io/en/latest/

`customisations/6-python.el`

(use-package elpy
  :config
  (setq elpy-rpc-python-command "python3")
  (setq elpy-test-runner 'elpy-test-pytest-runner)

  (when (require 'flycheck nil t)
    (setq elpy-modules (delq 'elpy-module-flymake elpy-modules))
    (add-hook 'elpy-mode-hook 'flycheck-mode)))

Overview

Why Emacs?

Terminology/anatomy

Terminology/anatomy

Windows and frames

Terminology/anatomy

Major Modes

Minor modes

Vim Users

Vim-like modal editing and keybindins

Basic commands

Movement you might not know

Lines

Brackets

Functions

Getting help

Help functions

Outside Emacs:

Beyond the basics

Macros

Beyond the basics

Rectangles

Capitalisation

Beyond the basics

Working with windows

Beyond the basics

Miscellaneous

Beyond the basics

emacsclient

TRAMP

Basic customisation

Basic customisation

Installing packages

Use use-package

Magit

Multiple cursors

Auctex

Auctex

Basic commands

C/C++/Fortran

Example C project

xref

C/C++/Fortran

Compiling

Helm (previously Anything)

Helm

General use

Helm

Useful actions

Projectile

Back to C project

Projectile commands

Python