1. Chapter 3 Mastering Editors
Guide To UNIX Using Linux Fourth Edition
Chapter 3 (40 slides)
CTEC 110

2. Objectives
Explain the basics of UNIX/Linux files, including ASCII, binary, and executable files
Understand the types of editors
Create and edit files using the vi editor
Create and edit files using the Emacs editor
Chapter 3 (40 slides)
CTEC 110

3. Understanding UNIX/Linux Files
Almost everything you create in UNIX/Linux is stored in a file
Bit: binary digit
In one of two states: 0 or 1
Machine language: exclusive use of 0s and 1s as a way to communicate with computer
Used by earliest programmers
Chapter 3 (40 slides)
CTEC 110

4. ASCII Text Files Byte (binary term): string of eight bits
A byte can be configured into fixed patterns of bits
ASCII: American Standard Code for Information Interchange
256 different characters
Unicode
Supports up to 65,536 characters
Text files: contain nothing but printable characters
Binary files: contain nonprintable characters
Example: machine instructions
Chapter 3 (40 slides)
CTEC 110

5. Look at Page 113
Chapter 3 (40 slides)
CTEC 110

6. Binary Files Some things cannot be represented with ASCII codes
Binary files are used instead
Example: graphic files include bit patterns
Bitmap: made of rows and columns of dots
Chapter 3 (40 slides)
CTEC 110

7. Executable Program Files
Text files containing program code are compiled into machine-readable language
Scripts are files containing commands
Typically interpreted, not compiled
Executables: compiled and interpreted files that can be run
Chapter 3 (40 slides)
CTEC 110

8. Using Editors
Editor: program for creating and modifying files containing source code, text, data, memos, etc.
Text editor: a simplified word-processing program
Used to create and edit documents
Two text editors normally included in UNIX/Linux are screen editors vi
Emacs
Line editor: works with one line (or group of lines) at a time
Chapter 3 (40 slides)
CTEC 110

9. Using the vi Editor vi is a visual editor vi is also a modal editor
Supports three modes
Insert mode
Accessed by typing “i”
Command mode
Accessed by typing Esc
Extended (ex) command set mode
Accessed by typing “:” in command mode
Download the vi editor document on Canvas for reference
Chapter 3 (40 slides)
CTEC 110

10. Creating a New File in the vi Editor
Chapter 3 (40 slides)
CTEC 110

11. Inserting Text When you start vi, you are in command mode
To insert text in your file, switch to insert mode
Use i (insert) command
To return to command mode, press Esc
Chapter 3 (40 slides)
CTEC 110

12. Repeating a Change
Use a period (.) to repeat the most recent change you made
Repeat command
Works in command mode
Chapter 3 (40 slides)
CTEC 110

13. Moving the Cursor
To move cursor use arrow keys (command/insert mode) or (in command mode) use:
Chapter 3 (40 slides)
CTEC 110

14. Deleting Text Deletion commands available (command mode)
dd is used for “cutting” text
Use “yank” (yy) command for “copying” text
Chapter 3 (40 slides)
CTEC 110

15. Undoing a Command Type u to use the undo command Example:
If you delete a few lines from a file by mistake, type u to restore the text
Chapter 3 (40 slides)
CTEC 110

16. Searching for a Pattern
To search forward for a pattern of characters:
Type a forward slash (/)
Type the pattern you are seeking
Press Enter
Examples: /\<top, /s..n, /pas[st], /!$
Chapter 3 (40 slides)
CTEC 110

17. Searching and Replacing
Screen-oriented commands execute at the location of the cursor
Line-oriented commands require you to specify an exact location (an address) for the operation
Preceded by a colon (:)
Operate in ex mode
Used for commands that perform more than one action
Example: searching and replacing
:1,$s/insure/ensure/g
Chapter 3 (40 slides)
CTEC 110

18. Saving a File and Exiting vi
To save file without exiting, use :w
To save and exit, use :wq, :x, ZZ
(Do this in command mode)
Chapter 3 (40 slides)
CTEC 110

19. Adding Text from Another File
To copy entire contents of one file into another file:
Use vi to edit the file you would like to copy into
Use the command :r filename
filename is the name of the file that contains the information you want to copy
Chapter 3 (40 slides)
CTEC 110

20. Leaving vi Temporarily
To launch a shell or execute other commands from within vi, use :!
Example:
:!cal
To run several command-line commands in a different shell without closing vi session
Use Ctrl+z to display the command line
Type fg to go back to vi
Chapter 3 (40 slides)
CTEC 110

21. Leaving vi Temporarily (continued)
Chapter 3 (40 slides)
CTEC 110

22. Changing Your Display While Editing
To turn on line numbering
:set number
To delete lines 4 through 6 (ex mode)
:4,6d
Chapter 3 (40 slides)
CTEC 110

23. Copying or Cutting and Pasting
The command yy copies (yanks) a specified number of lines
To cut the lines, use dd
Lines are placed in clipboard
Use p to paste the clipboard contents
Chapter 3 (40 slides)
CTEC 110

24. Printing Text Files
To print a file, use the lpr (line print) shell command
Example:
:!lpr -P lp2 accounts
Chapter 3 (40 slides)
CTEC 110

25. Canceling an Editing Session
Canceling an editing session will discard all the changes you have made
Or, save changes you made since last using :w
Saves file without exiting vi
Chapter 3 (40 slides)
CTEC 110

26. Getting Help in vi Use the help command Other alternatives: :help
man vi
From the command line
:!man vi
From vi (command mode)
Chapter 3 (40 slides)
CTEC 110

27. Using the Emacs Editor Emacs is a popular UNIX/Linux text editor
Not modal
More complex than vi
More consistent than vi
Sophisticated macro language
Macro: set of commands that automates a complex task
Uses: read mail, edit contents of directories, etc.
Powerful command syntax
Extensible
Chapter 3 (40 slides)
CTEC 110

28. Using the Emacs Editor (continued)
Chapter 3 (40 slides)
CTEC 110

29. Using the Emacs Editor (continued)
Chapter 3 (40 slides)
CTEC 110

30. Creating a New File in Emacs
Chapter 3 (40 slides)
CTEC 110

31. Navigating in Emacs To create a new file: emacs filename
To navigate in the file, use the cursor movement keys or Ctrl/Alt key combinations
Example: Alt+f
To save your work:
Use File menu
Use the save icon
Press Ctrl+x, Ctrl+s
To exit: use menu, icon, or Ctrl+x, Ctrl+c
Chapter 3 (40 slides)
CTEC 110

32. Deleting Information
Del or Backspace keys delete individual characters
Ctrl+k deletes to the end of a line
To undo a deletion, use Ctrl+x, u
Repeatedly undoes each deletion
Chapter 3 (40 slides)
CTEC 110

33. Copying, Cutting, and Pasting Text
To Copy-Paste or Cut-Paste:
Mark the text
Position cursor at the beginning, and Ctrl+Spacebar
Navigate to the end of the text you want to include:
Alt+w copies the text
Ctrl+w cuts the text
To paste, move to where you want to place the text
Ctrl+y (the yank command)
Chapter 3 (40 slides)
CTEC 110

34. Searching in Emacs One way to search in Emacs is to:
Press Ctrl+s
Entering string to find (on status line)
Pressing Ctrl+s repeatedly to find each occurrence
Use Ctrl+r to search backward
Other alternatives:
Use search forward for a string icon
On the menu: Edit  Search  Search
Chapter 3 (40 slides)
CTEC 110

35. Reformatting a File Alt+q turns on word wrap feature
Lines automatically wrap around from one line to the next
Chapter 3 (40 slides)
CTEC 110

36. Getting Help in Emacs
Emacs comes with extensive documentation and a tutorial
Tutorial is useful for getting up to speed quickly
Click Help menu  Emacs Tutorial
Or (in most versions), type Ctrl+h and then type t
To view general Emacs documentation:
Ctrl+h (press one or two times)
Or, man emacs at command line
Chapter 3 (40 slides)
CTEC 110

37. Summary
Bytes: computer characters (a series of bits) stored using numeric codes
The vi editor is popular among UNIX/Linux users
Three modes: insert (i), command (Esc), and ex (Esc :)
With vi, you edit a copy of the file placed in memory
File is not altered until you save it on disk
Emacs is a popular alternative to vi
Supports powerful command syntax and is extensible
Insert text simply by typing
Sophisticated macro language
Chapter 3 (40 slides)
CTEC 110

38. Command Summary
Chapter 3 (40 slides)
CTEC 110

39. Command Summary (continued)
Chapter 3 (40 slides)
CTEC 110

40. Chapter 3 Unix Exercises
Work through Hands-on Projects at end of chapter 3
Canvas: Review Questions
(Do not do questions 22,23,24 and 25)
Read chapter 4 before next class session
Quiz 3 Unix…
Chapter 3 (40 slides)
CTEC 110