CS 368-3 (2012 Summer) — 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)

CSL Accounts

For this course, you will need to write and run many Perl scripts as part of your homework assignments. There are a variety of ways that you can get access to a suitable machine:

Your own machine: If you have a computer that can run a reasonable version of Perl (e.g., 5.8 up through 5.16), you may use it. If you have basic questions about running Perl on your own machine, I might be able to help, but essentially you need to be able to support it yourself.
The Computer Sciences labs, in person: If you are enrolled in the course, then you should have a login on all of the instructional machines operated by the Computer Sciences Lab (CSL). If you have used a CSL account in the past, you probably still have it. If not, go to the instructional labs (the “mumble” lab seems like a good choice) on the first floor of Unit III of the Computer Sciences building (1210 West Dayton Street), and see the onscreen instructions for activating your account.
The Computer Sciences labs, remotely: Once you have an instructional account (see above), you can log into the instructional machines from anywhere else on the Internet.
- If you are using Windows, get a free remote-access application
  I 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 Perl 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 see on screen. What you need is generally called a “text editor”, ideally one made for editing programming files like Perl. 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.
On 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 Perl homework assignments on your own Mac, it will work great.
On Windows, I hear that Notepad++ is free and good (enough). If you have other Windows suggestions, let me know and I will post them here.
On Linux (and the Mac OS X command line), the two most popular programming text editors (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. The UW has free access to that site, but to get the free access, you must go through the my.wisc.edu portal, and then look in the Services tab. If you use the lynda.com site and it is helpful, let me know!

Perl on Windows

Although Perl is not officially supported on Windows in this course, people have successfully completed the course using Windows in the past. So it should be fine, but I cannot help you (much) if you get stuck.

I used to recommend ActiveState Perl to Windows users, but then a student wrote the following:

Firstly, I’ve found that ActivePerl doesn’t install correctly on my machine. After searching all over the FAQs and whatnot I still can’t figure out why; all I know is that the command prompt doesn’t recognize the terms “perl” or “perldoc” when I use ActivePerl. However, I found that Strawberry Perl works wonderfully. I can execute Perl stuff from my command prompt with no problem. I used the exercises in the [Learning Perl] book chapter 1 to test it out.

Second, I had been using Notepad to create/edit Perl script, and it works just fine; however, if you want to have the nice color-coding that Tim talked about in class, I’ve found that Notepad++ is perfect. I use that now.

Both of those programs are open-source and seem to have large online communities that can help answer any questions. Also, perl.org is a great resource.