This lab is due by:
8 AM, Wednesday January 17, 2001
 

[Turnin: Email your name, gt#, and answers to netiquette questions. Make a post to newsgroup.]
 
 

Objectives:
 

1.	Learn how to use telnet so you can get to your account.
2.	Learn basic Unix because your account is on a Unix machine.
3.	Learn about bananas, quota, and printing.
4.	Learn the text editor pico.
5.	Learn how to use the email reader pine.
6.	Learn how to use the newsreader tin.
7.	Learn netiquette.
8.	Learn workon commands.

 

Before You Begin This Lab

To do this lab, you must have activated your GT account. If you have not activated your account, refer to Lab 0 for how to do so.

Cluster Locations

If, for whatever reason, you find yourself unable to work on your assignments from your room, there are several public computer clusters from which you can access the applications required to complete your assignment. These clusters are located primarily around the center of campus.

For more exact locations of the above buildings, please refer to http://gtalumni.org/campusmap/.

Note that all of the Windows NT computers in the labs have Office 97 installed on them.  You may have purchased Office 2000 when you purchased your computer.  Office 2000 can read Office 97 files, so if you are planning to do work both in the labs and in your dorm room, you may want to save your office files with the 97 format so you can use them in both places.

Although you may be sitting in front of a Windows or Macintosh machine, school computing resources are networked on Unix machines. This means, for example, that the email you send out from your computer travels though a network of Unix machines before it arrives at its destination. Similarly, email that is sent to you travels though a Unix network and ends up on a Unix-based computer system called "acme". If you wish to read your email or work on one of these Unix machines, you need to log i n to them. This is accomplished by running the program Telnet.
 
 

Using Telnet
What is Telnet?

Telnet is an application that lets you log into and use a remote computer. Simply put, this means that you are going to access applications, information, and resources on a remote computer that is connected to yours by a network connection. (By remote   computer we mean a computer that could be located anywhere from the next room to the other side of the globe.) For all intents and purposes, it is just as if you were sitting at a keyboard in front of the computer, interfacing with it directly.

All telnet sessions are completely textual and command line driven, so there are no pretty pictures that graphically represent what is going on.

Starting Telnet:

You should already know how to run Windows programs from Lab 0. We will teach you how to use the standard Windows Telnet program. Start telnet by going to the Start menu, choosing Run... (abbreviated to Start -> Run... from now on) and typing "telnet" in the textbox (without the quotes).

The following window should appear on your screen:



Connecting to Acme

"Acme" is actually three computers: acmex, acmey, and acmez. The three computers all share the same resources, so it does not matter which one you use.

To connect to the acme systems:
Go to the Connect -> Remote System... (at the top of the telnet box).
Type "acme.gatech.edu" in the Host Name textbox. Leave everything else alone.
After a moment, a prompt labeled "Login: " will appear. Type in your GT-number here and press Enter.

NOTE: Unix systems are case-sensitive, so don't use capital letters or you will not be able to log in!

You will now be prompted for your password, which is also case sensitive, so do not use caps unless your password really has them.

If your information is correct, the telnet screen will display some information regarding the amount of time until your password expiration, and possibly a "Message of the Day" from OIT, Georgia Tech's Office of Information and Technology.

You will then be prompted to choose a default editor to use in your sessions. Choose pico. It is the easiest editor to use, and you can change it later if you want.

Now you should see a command prompt where you can type in commands. The first thing you should do is change your password. It should be something that you can easily remember, but something that no one else will be able to guess. Never use an English word as a password, and always have one or more punctuation marks and/or numbers in it. If someone finds out what your password is and does malicious things with your account, you are still responsible for the things done with your account!

To change your password, type "passwd" at the command line prompt. When you are ready to exit, type "exit" and press Enter.

Man Pages

So what else is there to do in this Unix environment? There are literally thousands of available UNIX commands that you can type at the command prompt, and you need to learn some of them. Each command is a combination of flags, options, and arguments that can be entered. It would take many reams of paper to print out a full description of all the commands with their options, so get familiar with the UNIX "man pages". The man pages are online manuals for all the commands and document all possible   flags and arguments available for use. To invoke the man pages, simply type:

man <command you want info on>

A good starting point is actually to type:

man man

If you know what you want to do but not what the command is called, use

apropos <word you want to search for>

or

man -k <word you want to search for>

These commands will search all the man pages for any mention of the word you wanted to search for.

UNIX File Organization

To use computers effectively, you need to have a general idea of how the files are organized.

Let us begin with a simple analogy. Pretend you are writing a collection of short stories, and you write a part of a story every day. You put each part on its own sheet of paper. Let us call this paper a file.

You store all the parts of a story together in story folders. Then you organize the stories into a few different topics, putting them into topic folders. Finally, you have one folder for the entire book. These folders are called directories.

A directory tree may look like this:

Files and directories are stored similarly on computers. They are organized in a tree-like structure, with directories, subdirectories, and files. For example, you may make directories for hw1, hw2, and hw3 in your account and store your homework answers in those directories.

Basic UNIX commands

Now that you've logged onto the acme system and you know how to get some basic information on its commands, here is a set of useful, basic commands.

UNIX File Permissions

File permissions allow you to control who can view, edit, and execute the files and directories you own. You can make some of your files available to other Georgia Tech students or anyone in the world, and it is also possible to ensure your files are private.

You can decide who can access the files in your home directory, but not files that are outside your directories. This is because they probably don't belong to you. Whoever owns them decides who has permission to access them. Type

ls -l

and you will see what is called a "long listing" of the files in your directory. It probably looks something like this:

The long listing gives you various information about your files (such as their size and time stamp). Over on the right side are the names of your directories and files, and permissions are represented in the long listing as the row of letters and hyphens on the far left of each file.Here's how to read the permissions:

A "d" in the first position means that you are looking at a directory.
After the d, the next three columns represent the owner's (gt2396a) permissions. The owner is generally the user that created the file. The three columns after that are for users i n the same group as the file's group (gtpsa) and the last three are for everyone else, usually referred to as other or world.

All Georgia Tech students are part of the gtpsa group, so whatever you set for the group will apply for all students, who are usually the only people you're concerned with anyway. However, in some cases you will want to grant access to the "whole world". For example, any file you want to appear on a web page must be accessible to the whole world.

The r means that the file or directory is Readable by whoever it applies to, the w stands for Writeable, and x means eXecutable. For instance, hw3.txt is r readable and writeable by the owner, but only readable by the group and the world.

For a directory, the x permission indicates permission to access that directory to use files in the directory. You need r permission on a directory in order to perform an ls in the directory. It is important to note that directory permissions work in conjunction with file permissions. To access files, both file permissions and directory permissions must be set correctly. For example, if someone else's directory has the permissions

 

drwx--x--x

2

gt1232b

gtpsa

512

Aug 8 20:21

public

then you can make a copy of any file in the public directory (assuming the file has the appropriate read permission). However, you could not run ls while in the public directory.

To change the permissions of a file, you use the chmod command (which means "CHange MODe"). There are two ways to use chmod -- with letters (symbolic), or with numbers (actually the octal bit pattern that the symbols are translated to). We'll just discuss the symbolic forms; you can read the man pages on chmod for more information. The format of chmod is

chmod <WHO> <GRANT> <PERMISSION> <FILE or DIRECTORY>

Here are a couple of commonly used commands and what they do:

chmod og+rx <directory>

Make <directory> publicly readable and executable, so anybody can do an ls on the directory and can get things out of the directory.

chmod og+r <file>

Make <file> publicly readable so that anybody can view its contents.

chmod og= <file>

Make sure that nobody other than you can read, write, or execute <file>.

It is extremely important that you know exactly who has permission to view, change and execute your files. In fact, it is your responsibility to ensure the security of your files. There have been an innumerable number of academic misconduct cases that involved a student copying files directly from another student's directory simply because he or she had access to them, regardless of whether or not the thief even knew the victim. Protect your files!

Core files

Perhaps one of the most annoying experiences that a computer user experiences is a program crashing. Anyone who has worked with a computer program, regardless of the operating system, has experienced a crash. Different operating systems, how ever, handle crashes in different manners. Windows and Macintosh attempt to hide the messiness that a crashed program can leave behind, hopefully without taking out the entire system (although they are sometimes less than successful). UNIX, on the other h and, records some pertinent information about how and when the program crashed, and leaves that information in a file in your directory named "core" (CS slang calls this "dumping core", and the file itself a "core dump"). If you continue with your studies in Computer Science and programming, you can actually learn how to use these core files to debug the programs you use. For our purposes, core files are a space-consuming nuisance. They can grow to several megabytes in size, so it is important that you check   your directories for core files on a regular basis, especially if a program you are working with on acme or any other UNIX system exits abnormally. Usually the system will notify you of the files existence with an error such as:

Segmentation fault (core dump)

or

Bus Error (core dump)
 
 

Simply perform an

rm core

to remove the file.

The Office of Information Technology controls the computing resources that Tech students access. There are some things that you must know about your account. You can read about these in more detail in the OIT FAQ (Frequently Asked Questions page).

Bananas

The word "banana" stands for Basic Allocation Negotiable Across Network Access and is also known as "funds", "Allocation Units", or "AU". You are allocated a certain number of bananas each semester, and you use them up when you store files o n acme or use acme, Tech's laser printers, the Rich cluster, etc.

To find out how many bananas you have and how many you have burned up already, type "usage" at the command prompt.
To find details about what each service costs, type "man rates" at the command prompt.
You need more bananas if you have used up 85% of your allocation! Send an email to help@cc.gatech.edu if you used them up doing work for a CS class.

Quota

Contrary to what you might think, you cannot store as much stuff in your GT account as you like. Every student has a quota on the amount of data they can store on acme, and it is usually 10 MB. If you go over quota, you will be placed in a restricted shell that only allows you to use ls and rm. To get out of the restricted shell, you must delete enough files so that you are under quota again.

Printing

To use Tech's laser printers, you must transfer your file to acme, telnet to acme, and use the prnt command. Or you have to go in to the Rich or Library Mac clusters to print.

How to Print

Prnt is invoked with prnt [options] <filename>. Here are some options you can use:

So if you would like to print a simple PostScript file, you would use

prnt -dest central-ps -type ps filename.ps

 
Also note that there are many more options available.  To view them all, try

man prnt

Where to Pick Up Your Printouts

If you printed from the clusters and sent your document to the appropriate printer, you only have to walk to the printer in the room for your printout. If, however, you printed from somewhere on campus to central-ps, you will find your printout in your GT-bin in OIT. The GT-bins are metal bins along a wall of OIT. Your printout will be in the bin labeled with the last two digits of your GT-number. So if your GT-number is gt1234a, you will find your printout in bin GT34. Please wait three hours before going to your bin to retrieve your document, and leave other people's printouts in the bin!

How to Change Your Default Editor

There are many reasons for making a new file. In this class, you will write your homework in a new file each week. To do this, you need to know how to create and edit text files.

All files must have a name. You can pick any name you like for the file as long as it is all one "word".

For example:
 

hw7hw7 ans	{Not OK, there is a space}
hw7_ans	{OK, still all one "word"}
hw7.i.love.1311	{Still OK}

When naming a file, DO NOT use certain characters. For instance, some characters like $, &, *, (, and ) have special meanings. As a rule, just use letters, numbers, underscore (_), dash (-), and period (.) to name files.

Acme has many different editors. Some popular ones on UNIX are emacs and vi. Right now, you are going to use pico (Pine Composer) because it is very easy to use and may remind you of other editors you have used be fore. You will learn emacs and vi in a lab in a few weeks, or you can learn them on your own before then.
 
 

Using Pico
To create a file with your hw7 answers in it, you would type:
pico hw7.ans
This tells acme that you want to use pico to edit the file named "hw7.ans". If that file already exists, pico will open it and display it on the screen. You can then make whatever changes you want to it. If it does not exist, pico will create it and allow you to type whatever you want into it.
Just about everything you need to know to use pico is always displayed at the bottom of the screen. Notation such as ^X means "press and hold the Control key while pressing X". Here are some useful keystrokes to know:

For practice, create a text file using pico. Write a few sentences about what you did over the break (bet you have not done this since second grade!). Use an appropriate filename. To save it, just exit, and it will ask you if you want to save it.
 
 

Email

Email stands for Electronic Mail. There are many different ways to move information on the Internet, and mailing a letter is probably the most common. When you mail a letter, you are doing nothing more than moving a file from one user on one machine to another user, possibly on another machine.

Your GT-account is capable of receiving mail from and sending mail to computers all over the world. Your e-mail address is: gtnum@prism.gatech.edu. You can use many different programs to send and read mail. The standard one on UNIX machines is mail. It does the job, but like many "standard" things, it is not very user friendly. Some of the more commonly used programs are mutt, elm and pine. We are going to show you pine since it is probably the most intuitive of them all. We encourage you to try the other ones.  It handles most of the details for you. You start it up by typing

pine
 
 

This is what pine might look like:

Pine is a menu-driven program.  Notice the area at the bottom that shows you what keys will do what.  You can either use the arrow keys to move the highlighted choice, 'P' and 'N' to move the highlighted choice, or you can type the letter of the menu choice.  Pressing 'L', for example, will take you to the folder listing:

From here you can select INBOX, where the mail you have received will be kept, or sent-mail, where a copy of mail you have sent will be kept.

Above is a sample INBOX with the important fields labeled.  New (unread) mail will have the letter 'N' appearing before the message number.  Messages are numbered sequentially, beginning with 1 (for the first e-mail received).  There are many features available in PINE, and you can learn more about the advanced options through the excellent online help available by pressing the '?' key.  Note also that the menu area at the bottom has changed to give you new choices for this screen.  Pressing 'R', for example, will reply to the selected e-mail.

To compose a message, press 'C', and you'll see something like this:

How to Send Email
 

		1.	a.	If you want to create a brand new email (not reply to an existing email), press "C" to Compose a message.  Fill in the email address of the recipient. Use commas with more than one recipient.  Fill in the subject of the message
			b.	If you want to reply to a message, highlight the message while in your inbox screen and press "r".
	2.		In the Cc field, , fill in the email address(s) of anyone that you would like to send a copy to, or hit Enter if you do not want to send a copy to anyone. Use commas with more than one recipient.
	3.		Type in your message. You'll notice that this interface is very similar to pico; in fact, pico stands for pine composer!  If you want to read in the contents of a file, use ^r.
	4.		When you are finished, press ^X to sent your message.

From here on out you are responsible for checking your mail at least once per day. You are responsible for anything that is mailed to you, and because it is the easiest way for TA's to communicate with all of the students in their sections, you may frequently recieve messages from your TA.
 
 

Newsgroups

Another way that you can communicate with other people anywhere in the world is through "newsgroups". A newsgroup is just a collection of messages about a particular topic, much like an electronic bulletin board. Someone subscribed to a news group can read the newsgroup and everything posted on it. The first field of the newsgroup name tells you what it is about. For instance, all of Georgia Tech's internal newsgroups begin with "git", while worldwide newsgroups for recreational activities start with "rec" and groups for computers start with "comp".
 
 

Newsgroups for 1311x
In this class, there are four newsgroups you need to deal with.

You are required to read git.cc.class.cs1311x.announce because that is where all the announcements go. Only TA's and the professor may post here. For example, your TA's may post about a change to an assignment, or your professor may post about additional lecture material. You are responsible for reading all the information posted on this newsgroup.
The other newsgroups for the class are for you to ask questions about the course. You are not required to read them, but they can be really beneficial to you, and we encourage you to read them. If you do not understand what a question on a homework assignment is asking, or if you need a starting place with a problem, or even if you are just lost and want some help, you can post to the appropriate newsgroup. Questions about recitation (homework, quizzes, etc.) go to git.cc.class.cs1311x.homework, while questions about labs go to git.cc.class.cs1311x.lab.
On either of these last two newsgroups, if you know the answer to someone else's question, you can post the answer there. If a question is unanswered, a TA will answer it in a few hours. Also, remember that 100+ people have to read each message that is posted, so if you are not sure if something is appropriate for the git.cc.class.cs1311x.questions and lab groups, don't post it. It just wastes everyone's time. This includes complaints, whines, ads, and stupid comments. There is ANOTHER newsgroup for this and just about everything else (religion, politics, chitchat...), and it is called git.cc.class.150x. You are not required to read it.
Be very careful what you post to cs1311x.questions. It must not pertain to homeworks, quizzes, or labs! Your TAs are not expecting urgent questions to show up there and so may not read them as often as the homework, quiz, and lab newsgroups.
Also, since part of this lab deals with newsgroup usage, inappropriate behavior on the newsgroups at any point during the semester may lead to a penalty on your grade for this lab.

Tin
Introduction
The idea behind newsgroups is to allow you to "post" an article to a newsgroup so that everyone subscribed to that newsgroup can read your article. Newsgroups are sort of like a newspaper which everyone can read and also can publish their own stories and announcements. The newsreader we are about to teach you is not the standard newsreader on all UNIX machines. The standard newsreader is rn, "read news", but we will teach you tin because it is the easiest program to use. OIT (Office of Information Technology) does not maintain tin. Rather, tin is part of "gtwreck", a collection of software applications maintained by a group of students. Feel free to learn rn, trn, or nn on your own to find out which one you like best.
Using Tin
You can run tin just by typing "tin" at the acme prompt.
As tin starts, it will ask you if you want to subscribe to any new newsgroups that have come into existence since the last time you used tin. Usually you will not want to, so you would just hit return to say "no" to each new newsgroup, or you can hit "q" to say no to all the new groups. When you have gotten through all the new groups, you will be at the Group Selection screen.
At this point, you will see a list of all the newsgroups to which you are currently subscribed.

To access the online help, just hit "h".

How to Subscribe to a Newsgroup

If, for example, you want to add the newsgroup git.test, you would type
g git.test
Tin will ask you where you want to put the new group. This is really asking if you want to see it at the top, bottom, or somewhere in the middle of the list of newsgroups. Typically, you would want it at the top, so press "1" now. After a moment, you should see git.test at the top of the screen.

Here is an example of a Group Selection screen:

 
What is a Thread?
tin and many modern newsreaders "thread" the articles. This means that all of the articles posted to a newsgroup about a given subject are linked together in one group. If you look at a thread, you will first see the first article of that subject, followed by all the responses to the first article that have been posted. This can lead to some confusion at first, because every time someone posts a "follow-up" to an article, that thread becomes active again and thus reappears   in the list of unread articles. This may bother you at first, but in time will seem intuitive.
Reading a Newsgroup
To read git.cc.class.cs1311x.announce, first add the newsgroup, then if you have more than one newsgroup, you would use the up and down arrow keys to highlight the announce newsgroup. Once it is highlighted, press the Enter key.
After the system takes a moment to thread the articles, you will be at a screen where all the articles are listed. You will see a listing of all the articles (by subject and author) which you have not read, or old articles to which there have been "follow-ups" posted. The articles are numbered on the left of the screen. Next to the number, there is a plus (+). This indicates that you have not read some articles in that thread. A number may follow this plus. That number indicates how may people have followed up to that article.


So if you see

this means that "George Burdell" posted an article about homework 1, problem 1. The 4 means that four people responded to George's question since the last time you read news.
From this screen you can read all of the articles by pressing Enter when the first article is highlighted, and then just pressing the space bar to go through each article in order. Tin also tells you how many posts are left in the thread and how many posts are left in the newsgroup in the heading of each post:

You can press the "tab" key at any time to go to the next unread article. This will stop you from seeing any articles that you have already read.
You can also use the arrow keys to navigate between threads and between articles within a thread much like you would move in elm to read your mail.

Reading Articles Again
Once you have read an article, tin remembers that you have already seen it, and assumes that you do not want to see it again. This means that once you read an article, it will not re-appear again.

To see articles that you have already read, type "r".

This tells tin to show all read and unread articles. It does not change anything. Tin still remembers that you read them. It just allows you to view old articles. If you press "r" again it will return you to the normal view of exclusively unread articles. The next time you enter tin, it will only show you unread articles.

 
 

Posting Articles

First, note that you cannot post to git.cc.class.cs1311x.announce. However, you are encouraged to post to git.cc.class.cs1311x.questions and .lab with any questions you have about the assignments. You are also encouraged to answer any questions   you see to which you know the answer.

How to Post an Article:

Following up to an Article
To publicly respond to someone else's post, press "f" while looking at their post. From here, the process is the same as if you were posting a new article. The only difference is that your subject line will be the same as the original post and thus will appear in that thread.

 
 

Replying to an Article

To privately respond to someone else's post through email, press "r" while looking at their post.
 
 

Searching in Tin

Before you post a question to 1311x newsgroups, make sure no one has already asked the same question! Asking a question that has already been asked and maybe even answered just wastes people's time. Within a newsgroup, there are three ways to search for a text string:

To search for an author, press "a". To search backwards, press "A".
To search for text in the body of a message, press "B".
To search for text in the thread title, press "/".

Cancelling an Article
Oops, you made a mistake and want to delete an article that you posted. Find that article again, then hit "D" (shift-d) and "d" to delete the post.
Netiquette
Netiqutte is the etiquette used in communicating with others through the Internet. It is one of the most important things for new users to learn! The surest way to make enemies on the net is to break netiquette. Do not commit this sacrilege! Be a good netizen (citizen of the Internet community) and follow these rules!
Terms & Definitions

General Netiquette

Additional CS1311x Rules & Netiquette

Your Assignment

We introduced a lot of important information in this lab, so now we must make sure you have absorbed it.

Procedure