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 you’re 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 can’t see it, doesn’t 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 won’t be able to change the file in any way, you’ll 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-<space> • The position of the cursor when set • Point • Wherever the cursor is located

17. Using The Mark And Point • Cntrl-w • Kills (cuts) the region from the mark to the point • Forwards or backwards doesn’t 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

20. 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

23. 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!

31. 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