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Introduction to EMACS and XEMACS. CMSC 121 Introduction to UNIX Much of the material in these slides was taken from Dan Hood’s CMSC 121 Lecture Notes. Emacs Background. Emacs is a powerful and extensible text editor. Emacs originally was an acronym for E ditor MAC ro S .
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Introduction to EMACS and XEMACS CMSC 121 Introduction to UNIX Much of the material in these slides was taken from Dan Hood’s CMSC 121 Lecture Notes.
Emacs Background • Emacs is a powerful and extensible text editor. • Emacs originally was an acronym for Editor MACroS. • The first Emacs was a set of macros written in 1976 at MIT by Richard M Stallman. • Emacs has become a standard editor used by programmers worldwide. • There are several varieties of Emacs, by typing emacs at the command prompt, you are throw into one of two modes: • The terminal-mode (from an ssh connection or without X Window): • This mode has no toolbars, and all commands are given via keyboard. • Do not think that this is a useless mode, as sometimes the only connection that you may have to a machine is remote. • The graphical-mode (requires X Window): • It looks similar to the terminal-mode, but with some added features for X. • There is a toolbar across the top of the window, from which many common tasks can be accessed. • You may wish to type emacs& (note the &), as this will free up the shell for other tasks (such as compiling).
XEmacs • This version of Emacs that has many enhancements specifically for X Window and should be launched locally. • There is a graphical toolbar (like MS Word) for basic options as well as a text driven toolbar for other options. • To invoke XEmacs just type xemacs. If you do not want to tie up the shell, use xemacs&.
Creating and Opening Files • To create a file, type the name of the file that you wish to create after the emacs command. Example: emacs foo.c & or xemacs foo.c & (& optional). • To open a file, type the name after the command, just as above.
Tutorial and References • Emacs comes with a built in tutorial. • To access it type F1 then T. • The tutorial covers many of the basic tasks, such as cursor movement to more advanced skills such as searching and replacing text. • References - from basic commands to the full manual • A BASIC EMACS Reference Card • A much more EXTENSIVE EMACS Reference Card • The Complete Manual Online - at GNU.org
XEmacs • XEmacs is a graphical variant of Emacs. • It too is freely available for download (http://www.xemacs.org/) and is also licensed under the GPL license (http://www.gnu.org/licenses/licenses.html#GPL). • XEmacs for Windows • For those of you who use Windows, that there are MS Windows ports of XEmacs. • XEmacs Commands • Mostly all of the Emacs commands are available to you under XEmacs • One useful XEmacs command: • Alt-G - Goto Line number
.emacs Configuration File • When Emacs (or XEmacs) begins, it looks for and reads a file named .emacs in your home directory to obtain configuration information. • Save this .emacs file (note the leading "dot") in your UNIX home directory to get the following features (you will need to restart emacs to invoke these options): • Automatic formatting - in accordance with coding style standards of many CMSC classes - (ALWAYS check with your instructor as to specific standards) • A working backspace key - backspace will now delete to the left of the cursor instead of invoking "help". • A more logical help key - It remaps CTRL-X? to be the new "help" key.
Customizing Emacs • The .emacs file contains user specific information and customizations to the XEmacs/Emacs editors. You can set up this file to do all sorts of customizations from building additional menu bars, to highlighting, to utility functionality. • There are 2 ways of going about customizing XEmacs/Emacs: • Manually edit this configuration file - this requires some knowledge of the language used to configure the editor and requires the user to manually edit the ".emacs" file. • Save configuration changes from within the editor - or you can save the changes from within the editor itself, and it writes out settings automatically to the ".emacs" file. • I find that I tend to use a mixture of both manual and automatic editing of the ".emacs" file.
Sample CMSC 201 .emacs File (custom-set-faces) (global-set-key "\C-h" 'delete-backward-char) (global-set-key "\C-x?" 'help-command) ;; set style to "Ellemtel" for C++ (add-hook 'c++-mode-hook '(lambda () (c-set-style "ellemtel"))) ;; set style to "Ellemtel" for C (add-hook 'c-mode-hook '(lambda () (c-set-style "ellemtel"))) ;; special effects for 'C‘ (add-hook 'c-mode-hook 'turn-on-font-lock)
;; no tabs please (setq-default indent-tabs-mode nil) (setq default-tab-width 4) ;; line & col nums (setq line-number-mode t) (setq column-number-mode t) ;; font coloring (setq font-lock-auto-fontify t) (setq font-lock-mode-maximum-decoration t) (require 'font-lock) ;; my email (custom-set-variables '(user-mail-address "your_username_here@umbc.edu" t) '(query-user-mail-address nil)) ;; some key bindings (global-set-key [(f1)] (lambda () (interactive) (manual-entry (current-word)))) (global-set-key [f2] 'ispell-word) ;; map that mouse wheel (global-set-key [button4] 'scroll-down) (global-set-key [button5] 'scroll-up) ;; automatic indentation upon return (global-set-key [(return)] 'newline-and-indent) ;; stop beeping (setq visible-bell 1) ;; make sure that every file has a newline (setq require-final-newline t) Another .emacs File
Emacs Modes • C Mode: Emacs supports C programming with a variety of options in C mode. • C -> Comment Out Region • C -> Uncomment Region • C -> Indent Line or Region • C -> Foreword Statement • C -> Backward Statement • C++ Mode: C++ mode also supports the same functions as under C mode, but under the C++ menu. • HTML Mode • Lisp Mode
Compiling in XEmacs • One of the nice features of XEmacs is the ability to compile source code from within it. • Do the following to compile code from within XEmacs: • Click on the Compile button • Edit the prompt in the window that appears that shows you what the current command is to compile. • By default XEmacs suggests the command "make -k". • This may or may not be what you want. • If you do not have a makefile (or don't know what one is) then you can change the command to something like "gcc -Wall -ansi *.c" by clicking on "Edit command". • The Compilation Output – this is where XEmacs is really useful. • If you have errors, gcc (for example) will report file and line numbers that the errors occurred on. • XEmacs goes a step further and hyperlinks that error containing the file and line number. • So when you click on it, it will open that file in the current buffer and jump to that line number. • XEmacs will also make sure that you saved all open files, to avoid compiling the sources without compiling them first.