Software Engineering on Unix

Emacs can be used as a unified environment for software development under UNIX. If things are set up properly, you can use it for everything.

We'll assume you're using Emacs 20. On Athena this is now the default. Some places are still using Emacs 19, but not many. Emacs 21 was released recently, but it takes a while for a new version to take hold.

Key bindings

• C-x means to hold down control and press the x key
• M-x means to hold down the meta (or alt or compose) key and press the x key.
• M-x can also be done by pressing ESCAPE then pressing the x key.
• C-x C-y means to hold down control and press the x key then let go then hold down control and press the y key
• M-C-x means to hold down control and alt keys and press the x key

Buffers and files and windows

C-x C-f

open file in a new buffer

C-x C-w

write file out with a different name

C-x C-s

save buffer under current name

C-x b

switch to buffer

C-x k

kill current buffer

C-g

cancel

C-_

undo

.emacs file and elisp

• At the core of Emacs is an interpreter for elisp, a variant of LISP
• Emacs is configured by writing elisp code
• Single line commands can be entered with:
  M-:
  enter elisp command

• .emacs file run on startup
• Examples in dotfiles locker on Athena:

  		add dotfiles; cd /mit/dotfiles/Emacs
  	

• Enter more complicated commands in lisp-interaction-mode:
  M-x lisp-interaction-mode
  enters lisp-interaction-mode
  C-j
  executes commands in lisp-interaction-mode

Regions

• Used to select regions of text on which to perform an operation
• Select with C-SPACE then move to end
• Also select with mouse button 1 and drag

Editing C code in c-mode

• C-mode allows you to edit C code more easily
  M-x c-mode
  enters C mode

• Indentation of code: press TAB anwhere on line

• Indent current region with M-C-\
• Make return auto-indent:

  		(define-key c-mode-map "\C-m" 'newline-and-indent)
  	

• Turning on auto parentheses matching (region face defines color)

  		(load-library "paren")
  	

• Other useful commands:

  M-x comment-region

  comments out regions

  M-/

  does dynamic expansion of words (finds closest match in buffer)

  M-C-a

  move to beginning of function

  M-C-e

  move to end of function

  M-C-h

  selects current function

  C-_

  undo

  M-x c-macro-expand

  runs cpp on region

  M-x line-number-mode

  prints line number at bottom of buffer (on by default)

  M-x goto-line

  goes to a specified line

M-x compile

• In c-mode, M-x compile runs make for you
• To make C-c C-v do a compile in c-mode:

  	;; Use C-c C-v in c-mode to do a compile
  	(defun my-save-and-compile ()
  	  (interactive "")
  	  (save-buffer 0)
  	  (compile "make -k"))  
  	(define-key c-mode-map "\C-c\C-v" 'my-save-and-compile)
  	

  If global-map is used instead of c-mode-map then applies to makefile and other modes.
• Middle button over an error goes to it in the source
• M-n goes to next error with:

  	(define-key c-mode-map "\M-n" 'next-error)
  	

Tags

• Keeps track of what is defined where
• Generate TAGS file with:

  	etags *.[ch]
  	

• To go to where a function is defined, do M-. over the function call
• To do a query replace over all files, do M-x tags-query-replace
• To search for something across all files, M-x tags-search
• To go to next occurance of search string, M-,

Faces and colorization

• List faces with M-x list-faces-display
• (set-face-foreground 'face "color")
• (set-face-background 'face "color")
• Highlight active region with:

  (transient-mark-mode 1)

• Use font-lock minor mode to enable syntax hilighting

  M-x font-lock-mode

  or

  (global-font-lock-mode 1)

• Update hilighting with C-=
• Example of setting C coloring for font lock mode:

          (new-face 'font-lock-comment-face "gray")
  	(new-face 'font-lock-variable-name-face "skyblue")
  	(new-face 'font-lock-keyword-face "burlywood")
  	(new-face 'font-lock-function-name-face "deepskyblue")
  	(new-face 'font-lock-preprocessor-face "burlywood")
  	(new-face 'font-lock-string-face "violet red")
  	(new-face 'font-lock-doc-string-face "green")
  	(new-face 'font-lock-type-face "lightsalmon")
  	

Adding filename to mode mappings

• Can add mappings with something like:

  	(setq auto-mode-alist
  	      (append '(("\\.pl$" . perl-mode)  
  			("\\.txt$" . text-mode)
  			("\\.doc$" . text-mode)
  			("\\.java$" . java-mode)
  			("\\.perl$" . perl-mode))
  		      auto-mode-alist))
  	

Using the shell within emacs

• Start shell with M-x shell
• For command line history, use M-p and M-n
• Particularly useful for things like sqlplus and other badly written programs.

Using GDB within emacs

• Start with M-x gdb
• For command line history, use M-p and M-n
• Some other commands:
  C-c TAB
  step one statement
  C-x C-a C-b
  in c file will set a break point at that line

Obtaining more documentation

• M-x info enters info mode
  • Clicking with middle mouse button follows hyperlinks
  • Provides documentation for lots of GNU software
• Menus on toolbar provides access to info and features
• C-h m provides help with the current mode

File management with dired

• Use C-x C-f to open up a directory rather than a file
• f descends into subdirs and opens files
• o opens files in other windows
• d marks files for deletion
• u unmarks marked files
• x deletes marked files
• C copies files
• R renames files

Using RCS and CVS from inside Emacs

• C-x v v does the next logical command.
  • If the file is not under version control, add it or start an rcs file for it.
  • If the file is not up to date, update it.
  • If the file is has unchecked in changes, check them in.
• C-x v = diff with most recent version.