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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Command Summary Chapter 3 (40 slides) CTEC 110

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

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