1. You do want to create and edit programs?
UNIX/LINUX Editors
You do want to create and edit programs?
Copyright © 2017 – Curt Hill

2. Introduction We will not use a nice GUI IDE in dealing with LINUX
Such do exist but we will not use them
Instead we use an editor that can use the console interface
This presentation looks at some of these
Copyright © 2017 – Curt Hill

3. Profusion
The UNIX philosophy is that any piece of software could be incrementally improved or substantially changed
This has led to all manner of variations of editors
Some of these have come to replace their predecessors
Or installed under their own name with an alias of what they replaced
Copyright © 2017 – Curt Hill

4. Editors There are many available Vi EMACS PICO JOE
Here are some of the most popular Vi
VIM
EMACS
PICO
Nano
JOE
Copyright © 2017 – Curt Hill

5. Types of Editors There are general types of editors
Modal and modeless
A modal editor has modes
In each mode there are only certain actions that can be done
Often one for commands, one for typing
A modal editor usually has a special type of command structure that everything can be done from one screen
Copyright © 2017 – Curt Hill

6. Vi Originally created by Bill Joy in about 1976
Loosely based on the ATT ed editor
Attempted to make the dumb glass teletypes of the day do something akin to full screen editing
Bill Joy used a Lear Siegler ADM 3a
See the display case
Probably the most popular editor for UNIX
Certainly so prior to EMACS
Copyright © 2017 – Curt Hill

7. Modes Vi has two modes Insert mode allows characters to be typed in
Insert mode and Normal mode
Insert mode allows characters to be typed in
The initial creation of text is necessarily in insert mode
Normal mode allows the entry of numerous commands
Typing an i in normal mode puts in insert mode
An Escape in insert returns to normal
Copyright © 2017 – Curt Hill

8. Insert Mode
At the bottom of the screen you should be able to see the word insert
The backspace deletes
Normal typing is inserted into the document
Escape leaves
Copyright © 2017 – Curt Hill

9. Picture
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10. Normal Enter this mode with an escape from insert mode
Most commands are one or two letters
Cursor motion
j - move down
k – move up
h – move left
l – move right
Copyright © 2017 – Curt Hill

11. File Commands Start with a : :r filename – Reads a file
:w – Saves the file
:w newfilename – Save as another name
:x – Exits Vi. Saves file
:q – Quits Vi without a save
Copyright © 2017 – Curt Hill

12. VIM Vi IMproved Mostly similar to Vi Does allow our cursor keys
Allows syntax highlighting for some languages
Default Vi for Ubuntu
Copyright © 2017 – Curt Hill

13. EMACS Another very popular editor for the UNIX
Also ported to most platforms including Windows
Dates to about 1976 at the MIT AI lab
Two important contributors are Guy Steele and Richard Stallman
An extraordinarily flexible editor
Our cursor keys will allow movement
Include PgUp, PgDn and Home
Written in a dialect of LISP
Copyright © 2017 – Curt Hill

14. Control Codes
Like many modeless editors it uses a series of control codes
File
^x^s – save current file
^x^c – exit EMACS
Search
^s – forward
^r – backward
Moves as you type
Escape leaves search mode
Copyright © 2017 – Curt Hill

15. Picture
Copyright © 2017 – Curt Hill

16. A Little LISP Please (defun calc-do-quick-calc (&optional insert)
(require 'calc-ext)
(calc-check-defines)
(if (eq major-mode 'calc-mode)
(calc-algebraic-entry t)
(let (buf shortbuf)
(save-excursion
(calc-create-buffer)
(let* ((calc-command-flags nil)
(calc-dollar-values calc-quick-prev-results)
(calc-dollar-used 0)
(enable-recursive-minibuffers t)
(calc-language (if (memq calc-language '(nil big))
'flat calc-language)) …
Copyright © 2017 – Curt Hill

17. Digression on Languages
The previous page was either the worst or best programming language
It is all a matter of opinion
LISP is functional language
Most common AI language
Copyright © 2017 – Curt Hill

18. Pico Originally the text editor for the Pine email system
A simple modeless editor
It uses control codes to move the cursor and all the other actions
Nano is a derivative
Next is a nano screen
Copyright © 2017 – Curt Hill

19. Some Codes Cursor control Control ^f – forward ^b – backward
^n – next line
^p – previous line
Control
^o – save file
^x – exit
Copyright © 2017 – Curt Hill

20. Picture
Copyright © 2017 – Curt Hill

21. Installation
By default Vi (or VIM) and Nano (variant of Pico) are installed
If you attempt to use EMACS or Joe it will ask you to install these with: sudo apt install joe
It will then attempt to do the install
This only works on packages that it knows about but are not installed
Copyright © 2017 – Curt Hill

22. Picture
Copyright © 2017 – Curt Hill

23. Summary All of these have more than adequate documentation on the web
GNU maintains several of the them
Even Wikipedia has entries on all of them
Some of these even have a short reference card to aid in use
Typically we use it until we are comfortable with the commands
Copyright © 2017 – Curt Hill