intro unix/linux 04
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intro unix/linux 04

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intro unix/linux 04 intro unix/linux 04 Presentation Transcript

  • Lesson 4-Mastering the Visual Editor
  • Overview
    • Introducing the visual editor.
    • Working in an existing file with vi.
    • Understanding the visual editor.
    • Navigating through a file.
    • Adding text to a file.
    • Avoiding confusion while entering commands to shell and vi.
  • Overview
    • Deleting text from a file.
    • Undoing editing commands.
    • Creating new files with the visual editor.
    • Making changes to the text.
    • Moving and copying text.
    • Writing a file and quitting the editor.
  • Introducing the Visual Editor
    • Bill Joy, a student of the University of California, wrote the vi editor.
    • The UNIX/Linux visual editor is a powerful, fast, command-driven screen editor.
    • The vi visual editor is available on all systems and is an essential tool.
    • The vi editor allows the movement of cursor to a specific location in a file.
  • Introducing the Visual Editor
    • The vi editor is present on every UNIX environment, uses few computing resources, and includes many tools.
    • Standard UNIX releases include vi, and Linux provides vim, which includes some vi improvements.
    • Command mode and append/insert are the two modes of the vi editor.
    • The command mode allows a user to access a file with basic vi commands.
    • The append/insert mode allows a user to insert data characters in a file.
    Introducing the Visual Editor
  • Working in an Existing File with vi
    • Files are central to the UNIX computing environment.
    • The visual editor is used to create new files and edit existing files.
    • The vi editor does not permit text to be added directly when editing a file.
    • The “cat” utility can be used for creating a file in UNIX.
    • We can edit the files created by the cat command.
    • We can access/open the files by giving the "vi filename" command.
    • The command will open the files in the command mode.
    Working in an Existing File with vi
  • Understanding the Visual Editor
    • Moving around in a file:
      • Opening a file in vi allows a user to delete, move, copy and paste and save and quit the file.
      • A user cannot insert characters while in the command mode.
      • The fundamental way to move the cursor in a file is to do it with the direction keys.
  • Understanding the Visual Editor
    • Moving around in a file (continued):
      • The vi editor interprets the h, j, k, and l keys as a command to the move the cursor in specific directions.
      • The workstation either flashes or beeps if an attempt is made to move the cursor beyond the existing text.
  • Understanding the Visual Editor
    • Moving around in the file (continued):
      • The vi editor also provides a forward search command for moving the cursor to a specific word in the text.
      • The /text is the forward search command for moving the cursor to a specified text.
      • The “n” command can be used for locating the next occurrence of a target string specified in the forward search command.
  • Understanding the Visual Editor
    • Working with text:
      • To insert characters to the file, we have to change from the command mode to the insert/append mode.
      • The vi editor provides the dd command for deleting an entire line of text from a file.
      • The “dd” command even deletes blank lines.
  • Understanding the Visual Editor
    • Working with text (continued):
      • After dd finishes deleting, it remains in the command mode.
      • The “x” (x-out) command deletes only a single character under the cursor.
      • The “a” command switches the vi editor from the command mode to the append mode and allows text to be entered to a file.
  • Understanding the Visual Editor
    • Working with text (continued):
      • The “u” command undoes the last text change made to the file.
      • The ESC key instructs the vi editor to switch from the append/insert mode to the command mode.
      • A user can check the mode he is working in with the ESC key.
      • The “o” command tells the editor to open a new blank line between the cursor line and the next line in the file.
  • Understanding the Visual Editor
    • Quitting the editor:
      • The “wq” command instructs the editor to write the file and quit the editor.
      • The “q” command can be used for quitting the editor if no changes are made to the file being edited.
      • The “q!” command instructs the editor to quit without saving the changes made to the file.
  • Understanding the Visual Editor
    • Creating and reading a file in the editor:
      • A new file can be created in the vi editor by specifying the filename with the vi command.
      • A file opens in the command mode. Text can be entered by switching to the insert/append mode.
      • The “r” or the “read” command locates a file and reads its contents into the current file, starting immediately after the cursor line.
  • Navigating Through a File
    • Using the direction keys:
      • The arrow keys and the h, j, k, and l direction keys, either alone or in conjunction with the number keys, make it possible to move the cursor to any character in a file.
      • The “set number” command tells the editor to display the line number on the screen.
      • The commands “G” and “:$” instruct the editor to move to the last line of a file.
  • Navigating Through a File
    • Lowercase “n” or “/” (slash) can be used to instruct the vi editor to search forward, whereas uppercase N or ? (question mark) is used to search in the backward direction.
    • The “set ignorecase” command can be used to switch off the case-sensitivity feature of vi’s search mechanism.
    • The “set” command can be used to view the environmental features that are currently set.
  • Navigating Through a File
    • The “w” command can be used to advance the cursor to the beginning of the next word.
    • The dollar sign ($) instructs the editor to move the cursor to the end of the current line.
    • The caret (^) and the zero (0) move the cursor to the beginning of a line.
  • Navigating Through a File Moving the Cursor in vi
  • Navigating Through a File Moving to a Specific Textual Character in vi
  • Navigating Through a File Moving the Cursor by Line Address and Location Display
  • Navigating Through a File
    • Two single quotation marks instruct the editor to return to the previous location in a file.
    • The display adjustment commands are used to adjust the workstation’s screen display to move forward or backward to a different block or section of code, regardless of its context.
    • CTRL-F displays the next screen of a text file.
    • CTRL-D scrolls down one half screen of a text file.
    • CTRL-D scrolls up one half screen of a text file.
    • CTRL-B displays the previous screen of a text file.
    Navigating Through a File
  • Adding Text to a File
    • The “i” (insert) command starts adding text to the left of the cursor.
    • The “a” and “i” commands instruct the editor to move from the command mode to the append mode and start adding text at the cursor position.
    • The “O” command is an instruction to open a line above the line where the cursor resides and shift to the append/insert mode.
  • Adding Text to a File
    • The “I” command instructs the editor to move the cursor to the beginning of a line and to change to the append mode.
    • The “A” command moves the cursor to the end of a line and switches the editor to the append mode.
    • The I and A command instructs the editor to switch to command mode.
  • Avoiding Confusion While Entering Commands to Shell and vi
    • The “who” command, when executed in a shell, lists the users currently logged on.
    • In the vi’s command mode, it moves the cursor to a specific position and moves over to the append mode.
    • In vi’s append mode, the characters are entered directly into the file being edited.
  • Deleting Text From a File
    • Multiple lines, words, and characters can be deleted by prefacing the delete command with a number.
    • The uppercase “D” command instructs the editor to delete the remainder of the line starting from the character under the cursor.
    • The “df*” command deletes the text from the cursor to the first character * on the current line to the right of the cursor.
  • Deleting Text From a File
    • The vi editor also allows lines to be deleted using the line number addresses.
    • The d command also allows a comma to be used for specifying a range of lines to be deleted.
    • Commands that employ line addresses require the ENTER key to be pressed after the command for execution.
  • Undoing Editing Commands
    • The “u” command undoes the last editing change in the file.
    • The vi editor in Linux allows multiple changes to be undone.
    • The “U” command undoes any number of changes made to the current line where the cursor is located.
  • Creating New Files with the Visual Editor
    • The vi filename command is used for creating a new file as well as editing an existing file.
    • The vi makes a buffer copy of a file if it exists, else it starts editing a memory buffer using the new filename.
    • A file created in vi can be made executable by executing the chmod command.
  • Making Changes to the Text
    • The “r” command instructs the editor to replace the character located under the cursor with the very next character typed in by the user.
    • It can also be used for breaking up a long line into parts.
    • The uppercase “J” command can be used for joining two lines of text.
  • Making Changes to the Text
    • The “R” command switches the editor to the “type-over” mode, wherein each letter typed replaces the character under the cursor as it moves down the line.
    • The “s” command substitutes the character under the cursor with the text typed in by the user until the ESC key is pressed.
    • The “cw” (change word) command allows a user to substitute a word or multitude of words for a single word.
  • Making Changes to the Text
    • The “cc” command deletes the text from the current line and moves you from the command mode to the append mode.
    • The “C” command puts the editor into the append mode and allows a user to change part of the line from the cursor position to the end of the line.
    • The substitute command, a colon command, is used to exchange one regular expression for another in a file.
  • Making Changes to the Text
    • The substitute command requires two words to be separated by slashes.
    • The “g” at the end of the substitute command is a flag and can be used for replacing all occurrences of the target pattern with the addressed lines.
    • The substitute command can also be restricted to lines having specific content.
  • Moving and Copying Text
    • The “yy” command instructs the editor to copy the contents of the line where the cursor resides.
    • The “p” or “P” command is used for pasting a new line in a new location below the cursor line.
    • The dd and p commands can be combined to perform a cut and paste operation.
  • Moving and Copying Text Commands to Move and Copy Text
  • Moving and Copying Text
    • Marking a place in the file:
      • The “m*” command instructs the editor to mark a line of text and assign it a label specified in the *; it can have a value from a to z.
      • A single quote character with the label name can be used for moving on to a specific label.
      • Vi allows deleting, changing, and yanking of text from the current position to the marked spot.
  • Moving and Copying Text The delete, change, and yank commands
  • Moving and Copying Text
    • Marking a place in the file (continued):
      • The mark command can also be used for simplifying the tasks of deleting, moving, and copying large blocks of text by marking both ends of the block.
      • Marking text is a powerful way to identify lines to delete, move, or copy.
      • The move or copy commands can be used for moving or copying a block of text specified using line numbers.
  • Writing a File and Quitting the Editor
    • The “w” command can be used for saving a copy of the current file to a new file.
    • The w or write command can also be used for writing a part or block of text from the current file to a new file.
    • The “w!” command instructs the editor to overwrite the contents of the file if it exists, else creates a new file for saving the contents of the current file.
    • The >> symbol, when specified with the w command, appends the text to the file specified.
    Writing a File and Quitting the Editor
  • Summary
    • The vi is the editor used to create and edit files.
    • Vi provides several utilities to edit text.
    • Append/insert and command are the two modes of the vi editor.
    • Files created in the cat command can be opened in vi.
  • Summary
    • A user cannot insert data without switching to the append/insert mode.
    • The I, a, i, A, o, and O commands instruct the editor to add text relative to the cursor position.
    • The vi editor provides the change (c), yank (y), and delete (d) operators for text operations.
  • Summary
    • The vi provides various utilities to move, edit, delete, and replace text.
    • The :wq is used for saving and quitting the editor.
    • The vi editor facilitates global changes, where the user specifies the target for replacement and the replacement text.
    • Linux provides an advanced version of the vi, namely the vim editor.