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Transcript of Introduction to Unix (CA263) File Editing By Tariq Ibn Aziz.
![Page 1: Introduction to Unix (CA263) File Editing By Tariq Ibn Aziz.](https://reader034.fdocuments.net/reader034/viewer/2022052312/56649f4f5503460f94c71f49/html5/thumbnails/1.jpg)
Introduction to Unix (CA263)
File Editing
By
Tariq Ibn Aziz
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Objectives
• After reading this chapter, you should be able to:– 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
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The Unix Language
• ASCII, American Standard Code for Information Interchange
• Originally, ASCII used only 7 bits (0 and 1) providing 128 characters
• Extended ASCII uses 8 bits to store 256 characters. For example English letter “H” has a decimal code 72. In term of bits, H is 01001000
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ASCII Text Files
• Computer files containing nothing but printable characters are called text file.
• Files containing nonprintable characters, such as machine instructions, are called binary files.
• Unicode offers up to 65,536 characters. • Unicode was developed because 256 character
in ASCII are not enough to support some languages, such as Chinese, that need more than 256 characters.
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ASCII Text File
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USING THE VI EDITOR
• The vi editor is a modal editor.• It works in three mode
– Insert mode• lets you enter text, is accessed by typing the letter “i”
– Command mode• Which is started by pressing Esc
– Ex mode• Employs an extended set of commands that were initially
used in an early UNIX editor called ex.• Press Esc and type (:) to enter extended command
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USING THE VI EDITOR
• Start the vi editor with the –e option (vi –e filename), which places vi exclusively in ex mode.
• To use the vi editor, it is important to master the following tasks:
■ Creating a file■ Inserting, editing, and deleting text■ Searching and replacing text■ Adding text from other files■ Copying, cutting, and pasting text■ Printing a file■ Saving a file■ Exiting a file
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Creating a New File in the vi Editor
1. Enter vi plus the name of the file you want to create, such as vi data.
2. Press Esc, type :w
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Creating a New File in the vi Editor
• Another Way to create a file1. open the vi editor without specifying the file
name with the vi command
2. You can save the file and specify a file name at any time by pressing Esc, typing :w filename
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Using the vi Editor (continued)
To create a new file in the vi editor, type vi and the name of the new file at the command prompt
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Inserting Text
• Before you can insert text in your new file, you must use the i (insert) command.
• In insert mode, every character you type appears on the screen.
• You can return to command mode at any time by pressing the Esc key.
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Repeating a Change
• When started, the vi editor is in command mode– To insert text into a file, you must switch to
insert mode – You can repeat the line just entered with the
repeat command (.)– Note: You must press Esc to use (.) to repeat
the command
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Moving the Cursor
• Designers of vi chose the letter keys because of their relative position on the keyboard.
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Deleting Text
• While still in command mode:– To delete text, move to a character and then type “x”– You can undo a command (reverse its effects) by typing “u”– To search for a text pattern, type a forward slash (/), type the
pattern, and press Enter
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Searching and Replacing Text
1. Searching and replacing is a line-oriented command that executes independently of the cursor position
2. To find more instances, type n while you are in command mode
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Save File and Exit
• Saving a file and exiting vi– You should always save the file before exiting vi,
otherwise changes are lost– To save a file and continue working on it, type the :w
(write) command– While in command mode, use the :wq (write and quit)
command to save and exit iv, or the :zz command to exit after saving
– You can also use :x to save and exit
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Save File and Without Exiting
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Information about file status
• If you are in an editing session and want to review information about the file status, press Ctrl+g or Ctrl+G
• The status line at the bottom of the screen displays information, including line-oriented commands and error messages.
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Adding Text from Another File
• To copy the entire contents of one file into another file: – (1) use the vi editor to edit the file you want to
copy into; and – (2) use the command :r filename, where
filename is the name of the file that contains the information you want to copy
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Leaving vi Temporarily
• If you want to execute other UNIX/Linux commands while you work with vi, you can launch a shell or execute other commands from within vi.– Go to command mode– Type :!cal (a colon, an exclamation point, and the
command) – press Enter.
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Using the vi Editor (continued)
1. Turn on line numbering when you want to work with a range of lines and refer to the line numbers to specify text
2. To turn on line numbering, use the :set number command
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Copying or Cutting and Pasting
• You can use the yy command in vi to copy a specified number of lines
• To cut the lines from the file and store them on the clipboard, use the dd command.
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Printing Text Files
• Sometimes you want to print a file before you exit the vi editor.
• Type !lpr and then type the name of the file you want to print.
• You might have two printers, lp1 and lp2.To print the file accounts to lp2, enter :!lpr -P lp2 accounts and press Enter.
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Canceling an Editing Session
• You might have to cancel editing session.
• To cancel session, enter :q! and press Enter.
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Getting Help in vi
• While you are in vi, press Esc, type :!man vi, and press Enter
• Type q and press Enter to go back into your editing session.
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Chapter Summary• Bytes are computer characters stored using
numeric code (e.g., ASCII)
• The vi editor is a popular choice among UNIX/Linux users to edit text files