emacs lecture

8/10/2019 Emacs Lecture

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EMACSBy Justin Higgins


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What is a text editor?

If youve ever used Microsoft word you knowwhat a text editor is (albeit a bloated one).

When you write a program in this class you will

use a text editor to write the file. In this file youwill write a series of commands which uponexecution will be performed.

In our case: we will use the text editor to write

IDL programs. Naturally the file you create willhave a series of IDL commands (theseAREdifferent from UNIX commands)


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Emacs vs VIM

There are primarily two text editors programmersuse: Emacs and VIM

Both have incredible functionality with VIM

focusing more onfewer keystrokesand Emacsfocusing on customization.

We will teach you Emacs, although it makes nodifference in the future if you become proficient

in one or the other.

Beware! You are choosing a side in the holiest ofholy geek wars.


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Open Emacs

To open emacs in a terminal simply typeemacs.

To directly open a file with emacs from the

terminal type emacs file_name If you do this on the ugastro server a new

window will open up with the GUI emacs.

If you have a Mac you can open Emacs interminal the same way, but you will not getthe same GUI (it will be built in the terminal).


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Emacs basics

Most emacs commands use a Ctrl-xplus some

characters to perform a command:

Examples:

To open a file: Ctrl-x Ctrl-f (then type the file

path)

To save a file: Ctrl-x Ctrl-s To close a file: Ctrl-x Ctrl-c


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Editing

To edit a file simply type in the main window.

Search forward: Ctrl-s (type the search string)

type Ctrl-s repeatedly to step through searches

Search reverse: Ctrl-r

Beginning of line: Ctrl-a

End of line: Ctrl-e

Beginning of file: Esc-


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Ooops! I made a poopsy!

To undo an action: Ctrl-_ (or Ctrl-x u)

To cancel a command you are typing: Ctrl-g

Example:

(I want to save a file but I accidentally typed:Ctrl-x Ctrl-c which will close it if I hit enter!)

Ctrl-gType multiply times if not stopping. this will work

anywhere within emacs


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Intermediate

Goal: Once you are comfortable you should

very seldom use your mouse/track pad or

have to type the arrow key repeatedly.

Go to a line: M-x goto-line

Query replace: Esc-% (type search

stringentertype replace string.enter, skip

a change with n and execute one with

spacebar)


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Markers

You can set a marker where you would like

some text operations executed. Do this by

typing: Ctrl-space (you will see mark set on

the bottom)

Now wherever you move youre the cursor

next, will define the mark up region (the

region you want to edit).


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Using markers (dont inhale)

Remove or kill a line: Ctrl-k

Remove a region of text:

Set marker Move cursor to bottom of remove region

Ctrl-w

IMPORTANT: After you remove a line or regionthat text is temporarily stored and can be

pasted by typing Ctrl-y (for yank)


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Buffers

You can have multiple bufferswithin one windowof emacs. That is OS will only show that oneterminal window of emacs is open, but in thatwindow can be MANY files.

Say you open a file (file1) and then want to openup another file (file2) whilst leaving file1 open.Simply type Ctrl-x Ctrl-f and the path for file2 andyouve now opened up file2 in a new buffer.

To switch back to file1, type Ctrl-x bfile1. If you forget which files are open in buffers: Ctrl-x

Ctrl-b displays available buffers


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Viewing multiple buffers

simultaneously This is perhaps one of the most useful tricks you will use in

emacs.

You will often want to compare two or more of yourprograms. Instead of opening up multiple emacs windowsyou split one emacs window into many. In each of thesewindows you can display a buffer.

To split the window horizontally: Ctrl-x 2

To split the window vertically: Ctrl-x 3

To close the window (YOU ARE IN): Ctrl-x 0 To close all the windows EXCEPT the one you are in: Ctrl-x 1

To switch between windows: Ctrl-x o


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Advanced: Macros

Eventually you become so 1337, so Super

Saiyan that even the shortcuts arent fast

enough for you. Luckily you may define your

own shortcuts with macros.

Begin defining a macro: Ctrl-x (

Define one iteration of the operation

End macro definition: Ctrl-x )

Execute the macro: Ctrl-x e


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Iterative operations

To execute a command iteratively: Ctrl-u #

command (where # is the number of

executions)

Example:

To indent a region 4 spaces:

Define region.

Ctrl-u 4 Ctrl-x


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Last remarks

You will only master these by practice. If youtake the time to learn the commands theprogramming bottleneck is simply the

execution of your code (and not your typingspeed).

Of course, it is easy to get distracted withemacs shortcuts. Remember they are thereto simplify a taskthat is, if it is too muchwork to use a shortcut DONT USE IT!

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