Introduction to Unix CS 21

1
Introduction to Unix CS 21

• Lecture 8

2
Lecture Overview

• More detail on emacs and vi
• Regular expression matching in emacs and vi

3
Accessing All Emacs Commands

• Meta-x
• Tab completion
• Exploring all of the different commands
• Approximately 1800 of them

4
Quick Jump To A Line In vi

• G
• By itself, it jumps to the end of the file
• 3G
• Jumps to line 3
• Any number works

5
Quick Jump To A Line In emacs

• Meta-x goto-line
• Then type in the line to go to
• Which is faster?
• Which is better?
• Which is more conformant to Unix style?

6
Search And Replace In Vi

• s/old/new
• Replaces old with new on the current line
• s/old/new/g
• Replaces all old with new on the current line
• 1, s/old/new/g
• Replaces all old with new in the whole file

7
Query-Replace In Emacs

• Meta-
• Meta-x query-replace
• Prompts you for old pattern and new pattern
• Questions you on every instance if you would like
  to replace it

8
Change In vi

• C will delete the line youre at and put you into
  insert mode
• Changing the current line
• c works much like d
• cc change line
• cw change word
• c10 change next ten lines

9
Replace In vi

• From command mode
• r will replace a single character
• R will put you into Replace mode
• Everything you type overwrites what was
  previously there

10
Overwrite Mode In Emacs

• Hitting the Insert key changes modes in emacs
• Takes you into and out of overwrite
• You suddenly will find yourself overwriting
  instead of inserting
• Check for (Ovwrt)

11
Emacs Buffer Primer

• When emacs is run without any parameters, it
  opens up a buffer called scratch
• All files opened and all messages that pop up are
  stored in different buffers and are always
  accessible
• Window vs. buffer
• Just because you cant see it, doesnt mean it is
  gone

12
Switching Buffers And Multiple Windows

• Cntrl-x, cntrl-b
• List all buffers
• Cntrl-x b
• Switch to buffer
• Cntrl-x 4 b
• Switch to buffer in another window

13
Adding Or Getting Rid Of Windows

• Cntrl-x 2
• Add another window (vertically)
• Cntrl-x 3
• Add another window (horizontally)
• Cntrl-x 1
• Only show one window

14
Read Only Files In Emacs

• will appear on the bottom of the screen
  indicating that the file is read-only
• You wont be able to change the file in any way,
  youll just be able to read it

15
Read Only Files In vi

• vi will warn you when you attempt to modify a
  read-only file
• It will let you change the file, though
• If you attempt to save the changes, it will warn
  you again
• Using the !, you can force the changes
• vi will let you modify a read-only file!

16
The Mark And The Point

• In order to highlight large sections of text,
  emacs introduces the idea of the mark and the
  point
• Mark
• Set with Cntrl-
• The position of the cursor when set
• Point
• Wherever the cursor is located

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Using The Mark And Point

• Cntrl-w
• Kills (cuts) the region from the mark to the
  point
• Forwards or backwards doesnt matter
• Some actions automatically set the mark
• Cntrl-y
• Pasting (yanking) sets the mark

18
Parenthesis Matching In Emacs

• Emacs will warn you when parenthesis are
  mismatched
• ()
• Emacs will always tell you what a parenthesis
  matches
• On screen
• Temporarily highlight
• Off screen
• State what matches

19
Accessing Unix Commands in vi

• vi has access to the shell and can run commands
• !COMMAND
• Will allow you to run one command
• !!COMMAND
• Replace the current line with output of the
  command

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Inserting Files And Commands In vi

• r FILE
• Insert the contents of FILE directly where the
  cursor is
• ! COMMAND
• Pipe the contents of the current paragraph into
  COMMAND and replace the current paragraph with
  the output

21
Accessing Unix Commands In Emacs

• Oh yeah? Watch this!
• Meta-x shell
• Actually opens up a shell (command line) INSIDE
  of emacs that allows you to run any program and
  still move around, cut and paste, and do anything
  you want
• The shell is located in another buffer
• shell

22
Regular Expression Matching In vi

• Just like searching for a normal pattern
• Syntax is mostly the same as grep
• Some symbols must be escaped
• \?
• \
• \(
• \)
• Character sets are escape characters

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Character Sets

• \d digit
• \D non-digit
• \a alphabetic character
• \A non-alphabetic character
• \l lowercase character
• \L non-lowercase character
• \u uppercase character
• \U non-uppercase character

24
Special Syntax

• Magic
• . treated as special characters
• This is the default mode
• No Magic
• . treated as normal characters
• Must be escaped

25
Regular Expression Matching In Emacs

• Cntrl-Meta-S
• Regular expression search forwards
• Cntrl-Meta-R
• Regular expression search backwards
• Syntax is mostly the same as grep
• Some characters must be escaped
• \( \)

26
Colors In Vi

• Special types of files are recognized
• Programming languages
• Objects are colored depending on their status
• Keywords, comments, variables are all colored
  differently

27
Colors In Emacs

• Emacs as well has colors, but not necessarily on
  by default
• Meta-x font-lock-mode

28
Programming Modes In Emacs

• More than just colors
• C and C files
• HTML files
• VHDL files
• Perl, prolog, ml, lisp, shell programming
• Pretty much any language you can think of has had
  a mode in emacs written for it
• Some are more extensive than others

29
Startup Files

• .emacs
• Contains all the commands that get executed every
  time you start emacs
• Sets default values
• .XXXrc
• General form of startup files

30
Fun With Emacs

• Doctor
• Adventure
• Solitaire
• Pong
• Tetris!

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In Lab Today

• You will play around with both Emacs and vi
• You will try out both basic file editing as well
  as some of the more advanced features

32
Next Week

• We look more at shells and specifically we look
  at special features of bash
• Midterm next Thursday
• Covers all material up from the first day of
  class until next Tuesday