Introduction to UNIX

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Introduction to UNIX

• C. Vi Editor

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Overview of vi

• Performance Objectives
• 1. Start/End VI (vi, ESC, wq)
• 2. Move the Cursor and Window (h,j,k,l, f, b)
• 3. Insert, Change, Delete Text (i, a, x, dd)
• 4. Search and Replace text (/.../, n,
  s/.../.../g)
• 5. Move/Copy Text (ma, d'a, p)
• 6. Write and Read Files (w file, r file)
• 7. Tailor the VI Environment (set)

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UNIX Family of editors

• ex line editor
• ed subset of ex
• vi screen editor

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Why learn vi/ex?

• Available on most UNIX systems.
• Works with a variety of terminals.
• Needs no special keyboard definition files.
• Allows the use of ex commands from vi.
• Provides for a customized editing environment.

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Some Conventions

• vi commands do not require a ltCRgt.
• vi commands not echoed.
• ex commands begin with / ?
• ex commands are echoed and ended with a ltCRgt
• The character represents the ltctrlgt key.

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Vi Modes

• COMMAND mode
• The default mode on entering vi.
• Anything typed is interpreted as a command.
• INSERT mode
• Enter INSERT mode by typing one of several
  commands.
• Anything typed is interpreted as data.
• Exit INSERT mode by typing the ltESCgt key.

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Vi Modes
UNIX Shell
vi filename
ZZ or wq
Command Mode
i a o
ltESCgt
Input Mode
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vi Window Display
Line one Line two Line three Line
n Command line

File text
Null lines
EX cmd line
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Vi Window Positioning
vi window
f Display Next segment
File
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Basic Window Positioning

• Move window forward 32 lines f
• Move window backward 32 lines b
• Move window forward one line e
• Move window to line n of file n
• Move window to end of file G
• Move cursor up/dn left/rt
• 
  or
• h
  j k l

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Making Changes Permanent

• vi uses a temp file for changes
• Write file and quit editor wq
• Undo last command u or U
• Recovery vi -r filename

Perm File
Temp File
w
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Insert/Delete Functions

• Del current line dd
• Del current char x
• Insert before current char i ...
• Insert after current char a ...
• Insert after current line o ... (opens file
  at a line)

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More Vi Functions

• Open several files vi file1 file2 ...
• End editor q (does not save changes)
• Redraw screen l (L)
• Join this line with next J

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Search For a Pattern

• Search forward to pattern / ... /
• Search backward to pattern ? ... ?
• Advance to next pattern n
  (forward or reverse)

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Replace A Pattern

• Replace string with another s/.../.../
  (only on same line)
• Replace string (global) 1,s/.../.../g

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Moving Text

• ma mark the starting position with a
• d'a delete text into a buffer
• p put buffer contents after cursor

ma
Area to be moved
da
Insert location
p
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Copying Text

• ma mark the starting position with a
• y'a yank text into a buffer
• p put buffer contents after cursor

ma
Area to be copied
ya
Insert location
p
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Writing to a file

• write current file w
• write named file w
  filename
• overwrite named file w!
• write lines m - n to named file m,nw file

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Useful Functions

• Re-edit current file, discard changes e
• Edit named file
  e file
• Read in and insert file at cursor r
  file
• Execute command and return to vi !cmd

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Tailoring the Environment

• For current session set optionsltcrgt
• Example set nu ltcrgt will set line numbers
• To view possible settings
• set all
• noautoindent nonumber noslowopen
• autoprint nonovice tabstop8
• noautowrite nooptimize
  taglength0
• nobeautify paragraphs tagstags
  /usr/lib/tags
• directory/tmp prompt termvt100
• noedcompatible noreadonly noterse
• noerrorbells redraw timeout
• flash remap
  ttytypevt100
• hardtabs8 report5 warn
• noignorecase scroll11 window23
• nolisp sections wrapscan
• nolist shell/bin/csh
  wrapmargin0
• magic shiftwidth8 nowriteany
• mesg noshowmatch
• nomodelines noshowmode

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Order of Evaluation

• On startup, vi sets options defined by EXINIT
  variable.
• Then options defined in /.exrc file.
• Settings in /.exrc take precedence.
• Setting in .exrc file in CWD take precedence over
  /.exrc file and EXINIT.
• Finally, set options of current session take
  precedence during that session.

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End of Module
Complete VI Editor Exercises