Transcript CS 497C - Lecture 12

CS 497C – Introduction to UNIX
Lecture 17: - The GNU emacs
Editor
Chin-Chih Chang
[email protected]
The GNU emacs Editor
• emacs was create by Richard Stallman (the
founder of GNU, now the Free Software
Foundation).
• The program was originally written as a set
of macros for the TECO editor.
• emacs is not available in all UNIX systems
but is standard on Linux.
• GNU emacs is more than an editor; it
handles a number of non-editing functions.
The GNU emacs Editor
• vi often does things with fewer keystrokes,
but emacs easily surpass vi when it comes
to searching and replacing and using
macros.
• After invoking emacs, you have a full
screen. 22 of the 25 lines are available for
editing.
The GNU emacs Editor
• The top one in reverse video shows a menu,
the lower one in reverse video shows the
mode line, and the bottom line is the
minibuffer showing an emacs-generated
message.
• In the mode line you can see the filename
and the cursor position (L1).
• Like most word processors unlike vi,
emacs is a mode-less editor.
emacs Preliminaries
• In the emacs documentation, key
sequences described as:
–
–
–
–
C-e – This is [Ctrl-e].
C-x C-b – This is [Ctrl-x][Ctrl-b].
C-x b – This is [Ctrl-x]b.
M-e – This is [Meta-e].
• On the PC, you can use the [Alt] key or
[Esc]-release to substitute [Meta] key.
emacs Preliminaries
• When you press a valid key sequence,
emacs executes a command associated
with the key.
• For instance, when you press [Ctrl-n],
emacs executes the next-line command.
• To canceling a sequence, use [Ctrl-g].
• emacs reads the file .emacs at startup.
emacs –q ignores the .emacs file at startup.
• Use [Ctrl-x][Ctrl-c] to quit emacs.
Inserting and Replacing Text
• The default input mode is the insert mode.
To switch to the overwrite mode, press the
[Insert] key or enter the overwrite-mode
command which can be done by the key
sequence [Alt-x]ov[tab].
• To enter a control character, first enter
[Ctrl-q] and then the control character.
• To save a file, use [Ctrl-x] [Ctrl-s].
• To save a file as a different filename, use
[Ctrl-x][Ctrl-w].
Saving Text
• To open a different file, use [Ctrl-x][Ctrl-f].
• emacs has an autosave feature which
automatically saves a copy of the buffer in
#filename#.
• To recover from the crash, use the recoverfile command:
[Alt-x]recover-file
The Digital Argument
• To perform a command as many times, use
the digital argument. The number is
prefixed by the [Meta] ([Alt] on PC) key.
• For example, to delete 5 characters, use
[Meta-5][Ctrl-d].
• The other way is to use the universal
argument – [Ctrl-u] such as
[Ctrl-u]5[Ctrl-d].
Navigation
• emacs uses the control keys to move in the four
directions. These keys are quite intuitive – b
(back), f (forward), p (previous line) and n (next
line).
• [Ctrl-b] – move left, [Ctrl-f] – move right, [Ctrlp] – move up, [Ctrl-n] – move down.
• To scroll full page forward, use [Ctrl-v]. To scroll
full page backward, use [Alt-v].
• To redraw the screen and position cursor at center
of screen, use [Ctrl-l].
Navigation
• To move to the beginning of a line, use
[Ctrl-a]. To move the end of a line, use
[Ctrl-e].
• To move the beginning of the word, use
[Alt-f]. To move the end of the word, use
[Alt-b].
• To move the specified line number, use
[Alt-x] goto-line [Enter] and then type the
line number.
Working with Regions
• To move to the beginning of the file, use
[Alt-<]. To move to the end of the file, use
[Alt->].
• To mark a region, first move the cursor to
the beginning of the section and use [CtrlSpacebar] or [Ctrl-@] and then move the
cursor to the end of the section.
• You can use [Ctrl-x][Ctrl-x] to toggle
between two ends.