A Guide to Unix Using Linux Fourth Edition

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 • :help • Other alternatives: • 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 A Guide to Unix Using Linux, Fourth Edition

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