1. A Guide to Unix Using Linux Fourth Edition
Chapter 3
Mastering Editors

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

5. A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

10. Creating a New File in the vi Editor
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

12. Repeating a Change
Use a period (.) to repeat the most recent change you made
Repeat command
Works in command mode
A Guide to Unix Using Linux, Fourth Edition

13. Moving the Cursor
To move cursor use arrow keys (command/insert mode) or (in command mode) use:
A Guide to Unix Using Linux, Fourth Edition

14. Deleting Text Deletion commands available (command mode)
dd is used for “cutting” text
Use “yank” (yy) command for “copying” text
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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], /!$
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

18. Saving a File and Exiting vi
To save file without exiting, use :w
To save and exit, use :wq, :x, ZZ (command mode)
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

21. Leaving vi Temporarily (continued)
A Guide to Unix Using Linux, Fourth Edition

22. Changing Your Display While Editing
To turn on line numbering, use :set number
Example: deleting lines 4 through 6
:4,6d
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

24. Printing Text Files
To print a file, use the lpr (line print) shell command
Example:
:!lpr -P lp2 accounts
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

26. Getting Help in vi Use the help command Other alternatives: :help
man vi
From the command line
:!man vi
From vi (command mode)
A Guide to Unix Using Linux, Fourth Edition

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
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28. Using the Emacs Editor (continued)
A Guide to Unix Using Linux, Fourth Edition

29. Using the Emacs Editor (continued)
A Guide to Unix Using Linux, Fourth Edition

30. Creating a New File in Emacs
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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)
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

35. Reformatting a File Alt+q turns on word wrap feature
Lines automatically wrap around from one line to the next
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

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
A Guide to Unix Using Linux, Fourth Edition

38. Command Summary
A Guide to Unix Using Linux, Fourth Edition

39. Command Summary (continued)
A Guide to Unix Using Linux, Fourth Edition