CS 368-2 (2012 Spring) — Notes for Beginners

If you are new to programming and/or running programs from the command line, there are some basic things you need to know:

How to log into a remote machine over the network
How to edit and save code files to disk
How to use the Unix command line (for Linux and Mac OS X, too)

Remote Logins

When we start using CHTC, everyone will need to access a certain Linux computer over the network. This is generally called remote access or remote login. However, especially if you are using Windows, you may want to set up your CSL account now and use remote access to work on a Linux instructional computer anyway.

In either case, here are some basics:

Get a CSL account
This was described in the slides for the first day of class. If you have used a CSL account in the past, you probably still have it. If not, head down to the CSL instructional labs (the “mumble” lab seems like a good choice), and follow the instructions on-screen.
If you are using Windows, get a free remote-access application
We recommend a free download called PuTTY, but really all you need is something that can use the SSH protocol to connect to a remote machine.
Try accessing your account
On Mac OS X, use the Terminal application; on Windows, use PuTTY or equivalent. These applications all look a bit different from each other, but generally speaking, you need to provide three pieces of information:
- A hostname (the remote machine’s Internet address, where NN is from 01–40):
```
mumble-NN.cs.wisc.edu
```
- Your username (from when you set up your CSL account)
- Your password (from when you set up your CSL account)
The CSL documentation has more information.

Editing Code

In this class, you must be able to create, edit, and save to disk Python and other files. Applications like Microsoft Word will not work for this purpose, because they add lots of extra, hidden stuff to the text that you actually see on screen. What you need is generally called a “text editor”, ideally one made for editing program files like Python. Here are some options and further resources:

If you are logging in to one of the CSL computers, it is probably easiest to use nano. From the command line, simply type
```
nano
```
and then hit return. Most of the screen is available for typing. But if you look at the bottom of the window, you will see things like this:
```
^G Get Help              ^O WriteOut
^X Exit                  ^J Justify
```
Those are commands that you can type. The ^ character is the “control” key on the keyboard, so try typing “control-g” to get more help on using nano.
If you are using Mac OS X, there is a very good, free programmer’s text editor called TextWrangler. This will not work when you are doing your work on a remote computer, but if you are editing and running your Python homework assignments on your own Mac, it will work great.
For more information, check out a couple of pages on the Python wiki: Python editors, and How to edit Python code.
The two most popular programming text editors on the command line (i.e., in place of nano) are emacs and vi/vim. Both are very powerful, but rather hard to learn at first. Which is best is largely a matter of personal belief (bordering on religious fervor at times); I will remain neutral on the matter. EMACS RULES THE WORLD!

Using the Command Line

Typically in Windows, Mac OS X, and even Linux, users interact with the computer and its programs using windows, menus, buttons, and other graphical interfaces. However, for the kind of programming that we are doing, we will be using the command line, a purely text-based way to run programs and view their output.

You will certainly need to use the command line for this course. On Mac OS X, use the Terminal application. On Windows, you could probably get by for the first half of the classes using the Windows command line, but I know nothing about it (it is different than the ones in Unix, Linux, and Mac OS X); it is best to get remote access to your instructional (Linux) account and use that.

Assuming you are new to the command line, you need to learn some basic concepts and commands. Here are a few resources that I have found that look helpful:

Available for free via Madcat is the O’Reilly book “Learning the UNIX Operating System” (get the [electronic resource] one). Ignore the sections (and whole chapters) on the graphical user interface(s) to Unix.
The website UNIX Tutorial for Beginners looks good.
There seem to be some promising video tutorials on lynda.com. I seem to recall that the UW has free access to that site, but I do not know how. Maybe check the DoIT website. If anyone finds that this option is free and helpful, let me know the details!