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

Chapter 3

Mastering Editors

Guide To UNIX Using Linux Fourth Edition

Chapter 3 (40 slides) 1CTEC 110

• 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

Objectives


• 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

Understanding UNIX/Linux 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

ASCII Text Files



Look at Page 113

• 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

Binary 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

Executable Program Files


• 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

Using Editors


• 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

Using the vi Editor


Creating a New File in the vi Editor


• 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

Inserting Text


• Use a period (.) to repeat the most recent change you made– Repeat command– Works in command mode

Repeating a Change


• To move cursor use arrow keys (command/insert mode) or (in command mode) use:

Moving the Cursor


• Deletion commands available (command mode)

• dd is used for “cutting” text– Use “yank” (yy) command for “copying” text

Deleting Text


• 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

Undoing a Command


• 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], /!$

Searching for a Pattern


• 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

Searching and Replacing


• To save file without exiting, use :w• To save and exit, use :wq, :x, ZZ

(Do this in command mode)

Saving a File and Exiting vi


• 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

Adding Text from Another File


• 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

Leaving vi Temporarily


Leaving vi Temporarily (continued)


• To turn on line numbering:set number

• To delete lines 4 through 6 (ex mode):4,6d

Changing Your Display While Editing


• 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

Copying or Cutting and Pasting


• To print a file, use the lpr (line print) shell command– Example:

:!lpr -P lp2 accounts

Printing Text Files


• 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

Canceling an Editing Session


• Use the help command– :help

• Other alternatives:– man vi

▫ From the command line

– :!man vi▫ From vi (command mode)

Getting Help in vi


• 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

Using the Emacs Editor


Using the Emacs Editor (continued)


Creating a New File 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

Navigating in Emacs


• 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

Deleting Information


• 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)

Copying, Cutting, and Pasting Text


• 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

Searching in Emacs


• Alt+q turns on word wrap feature– Lines automatically wrap around from

one line to the next

Reformatting a File


• 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

Getting Help in Emacs


• 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

Summary


Command Summary


Command Summary (continued)


• 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 Unix Exercises


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

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