CSE 341, Sp '06: Quick & Dirty Guide to Getting Started: Unix & Emacs

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Acknowledgment: These notes have evolved over the last few years, but are largely based on notes written by Keunwoo Lee in 2001.

Reflection X

We'll use Reflection X to give you a graphical interface for your Unix session on Attu (attu.cs.washington.edu).

Logging in from the basement labs

If you're going to be using the labs, everything is all set up for you. Simply double-click the "SSH-X attu" icon on the desktop. Type in your CSE account password and you're all set. Now type "xterm &" without the quotation marks to get an xterm.

Working elsewhere

We recommend you work in the basement labs where we have checked that the right software is already installed and the directions we provide are correct. If you still want to work elsewhere you have a few options.

Install the necessary software (emacs and sml (and possibly sml-mode for emacs) at first, DrScheme later, Squeak after that) on your computer. The links at the bottom of the course web page should help. Make sure you get the right versions.
Install Reflection X on your computer, using the CSE department instructions. What a Reflection X session does is connect you to a CSE UNIX server. Everything you type or click is sent to the server, which sends back to your computer what to display. So you're using the department's software installation.
For those savvy with terminals and ssh, it is possible to run emacs and sml directly in terminals after connecting via ssh to the department, but it is not particularly pleasant.
You can change your desire to avoid the department labs.

Basic Unix commands

To move around through the directory structure in your xterm window, you'll need to know a few basic Unix commands.

attu4% mkdir mydir
attu4% ls
mail  mydir
attu4% cd mydir
attu4% pwd
/homes/iws/sbfan/mydir
attu4% exit

In the above (the things within the quotation marks are commands to type, don't type the quotation marks themselves):

To make a directory, and name it, say "mydir", you would type "mkdir mydir".
"ls" lists what you have in your current directory.
"cd" will change directories. To change to a directory "mydir", for example, type "cd mydir". To move back out of a directory, type "cd ..", and to get back to your home directory, "cd ~".
To check where you are, type "pwd".
"exit" exits.
To get help on some command, say you want to know how to use "ls", type "man ls" and you will get the manual pages for that command. (Alternatively, you can use "info" in the same way.)

These are just the very minimum basics. For more info on Unix, look at the course help page on Unix.

Emacs

Now that you have your xterm open, let's open Emacs.

Type "emacs &" to open emacs in a new window. Note what happens if you don't type the "&"--you can't do anything in your xterm window. The "&" runs your program, in this case, emacs, in the background.

The cursor is a rectangular block and is referred to as the point.
The modeline displays information about the buffer displayed in the current window. A buffer is a logical "thing" that you are working on. When you open a file, it will be loaded into a buffer, typically with the same name as the file.
Every buffer is edited in a mode. The most basic mode is Fundamental, which provides only the most basic Emacs editing features. There are modes for many different languages.
There are many "special" buffers that do not correspond to loaded files. The one above is called *scratch*. This buffer runs in Lisp Interaction mode, which means that you can interactively type and evaluate Lisp expressions (try typing "(+ 1 1)" followed by Control-J while in *scratch*).

Emacs uses many key combinations involving the Control and Meta keys. Such key combinations are denoted C-x (Control-x (lowercase)) or M-x (Meta-x). On keyboards that don't have Meta, Alt is usually an acceptable substitute. If Alt doesn't work, ESC-x is equivalent to M-x.

A sequence of key presses is written like C-a C-b M-x, which would mean do the three actions in sequence.

The most important keys in Emacs

C-x C-c: Quits Emacs.
C-g: Cancels the current action.
C-x C-f: Opens a file.
C-x C-s: Saves a file.
C-x C-w: "Save as" (save contents to file with a name you type).

Getting help in Emacs (the next most important keys)

C-h: Help. Hitting this will display a short message in the minibuffer: C-h (Type ? for further options).
C-h t: Built-in interactive tutorial. Some people don't like this tutorial, but some people find it helpful.
C-h b: Key bindings. This lists all key bindings that are valid for the current mode. Note that key bindings change from mode to mode!
C-h a: Command apropos. After hitting C-h a you can type a symbol and a window will appear that lists all symbols and functions that match that phrase.

Some other useful keys:

C-x 2: Split the window into 2 buffers, one above the other. (Use the mouse or C-x o to switch between them.
C-x 0: Undo window-splitting so there is only 1 buffer.
C-x b: Switch to another buffer by entering its name.
C-x C-b: See a list of all current buffers.

SML/NJ

Once set up, it is more convenient to run SML/NJ in Emacs, but you can also run it directly from the terminal command prompt. Just type "sml" at your terminal command prompt. To get out of SML/NJ, type C-d.

To run it from Windows in the labs, you can find SML/NJ (Standard ML of New Jersey) in Programs under the Start Menu.

To load a .sml file into SML, type "use "filename.sml";" while within SML/NJ.

SML/NJ in Emacs

Remember the Emacs modes we were talking about earlier? You can run emacs in SML mode, but you'll have to set up a few things first. If you're using Linux/Unix from the CSE labs:

If you don't have a .emacs file, create one. Type "C-x C-f" and then type ".emacs". Now you're editing your .emacs file.

Paste the following lines of code into your .emacs file:

; SML/NJ stuff
(add-to-list 'load-path "/cse/courses/cse341/common/sml-mode")
(load "sml-mode-startup")

; Global coloring
(global-font-lock-mode)

That's it. To check if it works, you need to restart Emacs. Save your file (C-x C-s) and quit Emacs (C-x C-c), and open it up again. Open any file with a .sml extension (type "C-x C-f" and then "test.sml"). If your mode line says "(SML)", you're set!

If you are not in the basement labs, you need to do the following:

Download SML mode and install it yourself in some directory.
Use the above lines in your .emacs file, but change the first line to:
```
(setq load-path (cons "YOUR PATH HERE" load-path))
```

There are two ways to run SML/NJ from within Emacs

Type M-x shell in Emacs; this brings up a *shell* buffer. Then, type sml. SML/NJ should start up in this buffer, and you can interact with it just as if you were in a console window.
The other way is to open a SML file (like first.sml from the previous page), and then hit C-c C-l. If your sml-mode is properly configured, you will be prompted for the SML executable and the file to load, and a buffer labeled *sml* should pop up with the current file loaded:

Save an SML/NJ transcript

Often, you will want to save output of an entire SML/NJ session. How can you do this? Here's a few alternatives:

Method 1: Saving within Emacs

If you use the method described above for running SML/NJ under Emacs, you can save the *sml* buffer the same way you save any other buffer: switch to the buffer's window and hit C-x C-s. You will be prompted for a filename. You can save as many times as you wish.

Method 2: Copy and paste

In the X Window System, the idiom for "copy and paste" is to select a region, and then click the middle mouse button (the mouse wheel on an MS mouse suffices) at the spot you want to paste the selected region:

[GNU Emacs in sml-mode with a child SML process]

Method 3: Pipes

This method is only suitable if you want to run a single file through SML/NJ and capture the results, without actually interacting manually with SML/NJ. Invoke SML/NJ as follows:

sml < myinputfile.sml > myoutputfile.txt

The < sign means "redirect standard input from this file", and the > sign means "redirect standard output to this file". Pipes are a very important and powerful feature of Unix. Learn to use them!

Method 4: if you are in SML/NJ for Windows

Right-clicking within the window should bring up options for selecting all, copy/pasting, etc.

Accessing your UNIX home directories from Windows XP

If you're in the basement labs, your O: drive should already be mapped to your Unix home directory. Look under for the O: drive under "My Computer" in the Start Menu. To accesss your files, go to O:\unix\homes\iws\userid, replacing "userid" with your own CSE account username. All the files you saved while working on Attu should be there.

If you're in the labs and your O: drive isn't mapped, open up a Windows Explorer window (by clicking the "My Computer" from the Start Menu) and in the Tools menu item, select "Map Network Drive" and enter O: for drive and \\ntdfs\cs for folder. Click Finish. If you're at a computer that does not use CSE's name servers, for example in Mary Gates Hall or at home, you will need to use the fully qualified name, \\ntdfs.cs.washington.edu\cs.

For more info on this, see the CSE support page that discusses Microsoft DFS, which is what we just used.

Finally, there are other resrouces, including the course help pages as well as the CS Lab and Support pages.


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