Lab 1

Introduction

In this first lab you will be introduced to the computing environment in the Baldy 21 lab. If you are familiar with Unix you may know how to do some or all of the following tasks. Do them all the same. If you are new to Unix, these exercises will get you up and running with most of the tools you need to successfully complete the lab assignments of this course. Some further tools will be introduced as we need them in later labs.

You should not expect to finish all of these exercises during the allotted lab time. You should plan to return to the lab during open lab hours (hours when the lab is open but there are no formal labs scheduled) to complete your work.

Read through the entire lab before you start working, so that you know what to expect. Make sure you save your work often, and keep track of what you are expected to submit.

Objectives

The objective of this lab is to introduce you to the Unix operating system and some of the tools available to you so that you can work on the labs independently.

Preparatory work

Be sure you completed the preparatory work outlined in the Lab 1 Prep Work.

Lab Tasks

Your instructor has briefly gone through the tasks listed below during lecture to help prepare you for this lab. You must now carry out each of the following tasks on your own in the lab setting. Chapter references are to the Unix book you should have brought with you to the lab.

Logging in - Connecting to the system

Your first lab task is to log in to your CSE computer account. Your CSE account is valid on the computers in Baldy 21. This account is separate from your UBUnix account.

If you have not had a CSE account previously, your login name is the same as your UB-IT name. Your password is the same as your UB-IT password was at the time when your CSE account was created.

If you have previously had a CSE account (e.g. if you took any other CSE course last year where you received an account), your login name and password should not have changed.

Unix is the name of the operating system that is running on the machines in the Baldy 21 lab. An operating system (or OS) provides basic services to both programs (applications) running on the machine and to users who are working on the machine. Examples of services provided by an OS are a facility to read the contents of a file from a disk, or run multiple programs at one time (multi-task).

Gnome is a windowing system, or graphical user interface (GUI), to the underlying Unix operating system. Gnome is thus separate from the operating system. A windowing system manages windows on a screen and provides a graphical way of interacting with the operating system.

On personal computers it is becoming more and more difficult to distinguish between the operating system and the windowing system as they are becoming more tightly integrated. In the Unix world however, the separation is still clear and it is not uncommon for different users on a given system to use different window systems.

To log in:

If you see a window saying: "The greeter program appears to be crashing. I will attempt to use a different one." It is not crashing, just click OK.

You should see a welcome screen with a place for your username. Enter your username (UB-IT name), and then press OK.

You will then be asked to enter your password. Enter your password, and then press OK.

When Gnome is finished loading, you will be presented with a desktop. There will be a few icons on it that looks like this:

There is a panel across the top of the screen which has two menus on it. This is similar to the Start Menu feature of Microsoft Windows. There is also a panel along the bottom of the screen. If you want to know what anything does, hover your mouse over it and a little description will appear.

In case of emergency where you suddenly need to leave, such as your grandmother dying (it happens a lot in this class), let's discuss how to log out of the system before we go any further.
Just click on the "Actions" on the panel at the top of the screen, then select "Log Out".
You will probably receive a message asking if you're sure you want to log out. There's also a checkbox that says "Save current setup". If you want to save your setup (whatever that means), check this box. Then click on "OK" and you will be logged out. Remember to never leave the lab without logging out, even if it is "just for a minute"!

Spend a moment getting comfortable with Gnome. To move a window with a title bar (for example double click on 'Computer' to get a window), click and hold the left mouse button in the middle of the title bar and drag it to a new position. If you click on the small buttons in the title bars of the windows, different things will happen:

The rightmost button on the title bar:
Left-clicking this will close the window. Try it out: open a window and close it.

The button to the left of that (in the middle of the three):
Clicking this will toggle the window between "maximized" and "unmaximized"/"normal" modes. In maximized mode, the window will take up the full space of the screen. In normal mode, the window is not necessarily the full size of the screen and you have the ability to move it around and see other things on the screen as well. Try maximizing and unmaximizing some window.

The button to the left of that (the left side of the three):
Left-clicking on this will minimize the window. It keeps the program running but hides it from view. Now we need to get it back. Just click on the corresponding item on the panel along the bottom of the screen.

The button on the far left of the title bar:
Clicking on this will bring up a menu of different things you can do to the window. Try it out and see what can be done.

As previously mentioned, Gnome is just a windowing system that interacts with the underlying Unix operating system. To interact directly with Unix, we need what is called a terminal. Here are two ways to bring up a terminal in Gnome:

Right click on an empty space on your desktop and select "Open Terminal" from the menu.

Click on the Applications menu on the panel at the top of the screen. Click on "System Tools", then click on "Terminal".
The terminal window will look like this:

The > symbol is called a prompt. You will type commands into the prompt to get the Operating System to perform various tasks for you.

Adding the ampersand (&) to the end of a Unix command makes it run in the background. When a command runs in the background (as opposed to the foreground) you get the Unix prompt back so you can type another command if you wish to. In this way you can multi-task (have several applications running at once) without needing a terminal for each application.

The files which you create are stored on a machine called a file server, which is accessible from all of the workstations in the lab. In other words, it doesn't matter which workstation you log in at, you will be able to access exactly the same files. The computer which you will use in the Baldy 21 lab is called styx.cse.buffalo.edu, or just styx for short. This computer shares its files with several systems, one of which is called pollux.cse.buffalo.edu (pollux for short), which you can log into from other places around campus. If you want to work on the CSE servers from the residence halls or off campus, log in to yeager.cse.buffalo.edu.

Changing your Password

It is a good idea to change your password from your default password to something else. You should change your passwords often to help keep your account secure. You must never share your account password with anyone (including your friends and classmates). Read the section in Chapter 1 (pages 11-12) about changing your password. Passwords can only be changed while logged into hadar.cse.buffalo.edu. This is the only operation that you should do while logged into hadar. The rest of your work for this class should be done logged directly onto your machine. Do this now:

To log into hadar, at a prompt type:
ssh hadar
If you receive a message starting with "The authenticity of hose 'hadar (128.205.32.1)'..." type "yes" (without quotes) and hit enter. Ignore the warning that comes up. Then it will ask for your password by saying:
username@hadar's password:

where 'username' is your account name. Type your CSE account password. Nothing will show up, not even asterisks, this is normal. Hit enter and you are now logged on to hadar.cse.buffalo.edu. Follow the instructions in the book on how to change your password. Note: it may take a few minutes for the password change to work. This is normal. When you are done changing it, then type 'exit' at the prompt, and you will see:
Connection to hadar closed.
You are back on styx and can continue with the lab. The next thing you should do is type the command /projects/CSE115/Setup/115setup. One of the things this will do is create a file called cse115.epf for you. This file will be used when we start developing programs.
Because your CSE account is separate from your UBUnix account, changing the password on one account does not automatically change the password on the other. You should change passwords on both accounts on a regular basis.

Unix and utilities

In this section, you will experiment with some basic Unix commands, and learn a little bit about the way in which Unix organizes its file system.

Basic Unix directory structure

Like most file systems, Unix's is tree-structured. The root of the file system is named '/'. As a user on the system you have a home directory, where all your files are stored. Unix has a "shortcut" to represent your home directory. This shortcut is the tilde (~). Whenever you want your home directory, you can just type ~. To find out where your home directory is, type
echo ~

When I do this, I find out that my home directory is /home/csefaculty/adrienne. This means that my home directory adrienne is located in the subdirectory csefaculty, which is a subdirectory of home, which is an immediate subdirectory of the root directory (which is, as mentioned above, designated by '/'). "/home/csefaculty/adrienne" is a path which describes how to get from one directory (in this case the root directory) to another (in this case my home directory). A path can either be absolute (starting at /) or relative (starting at the current directory).
Every directory has two special entries, . and .. The entry . refers to the directory itself, and .. and refers to the directory's parent directory (i.e. the directory of which this one is an immediate subdirectory). The . and the .. are "shortcuts" as well. No matter where you are, if you want to use your parent directory, then you just use ...
The root directory is the only directory in the file system which does not have a parent directory. (Actually, this is not quite accurate. If you inspect the root directory you will find that there is a .. entry. The parent of the root directory turns out to be the root directory itself!)

Getting started with Unix
Below I have listed some basic Unix commands. Read the description of each, and carry out any exercises given.

ls - This command gives a listing of the files in a directory. Without any arguments, it provides a listing of the files in the current directory, and is therefore equivalent to

ls .

If you specify a directory using a path, ls will respond with a listing of the contents of the specified directory. Try typing ls at the Unix prompt. Do the other examples on the ls pages (pages 13-14).

cd - This command changes the current directory. Without any arguments, it changes the current directory to your home directory, and is therefore equivalent to

cd ~

If you specify a directory using a path, cd will set the current directory to the specified directory. One neat thing is that using .. as an argument to cd moves you to the parent directory. Do the examples of using cd on pages 15-16.

pwd - This command gives the current or present working directory. Unless you have changed your working directory since logging in, typing pwd should return your home directory path. Do the examples of using pwd on page 17.

piping input and output - It is possible to make the output of some command be the input of another command. This is done by creating what is known as a pipe between the two commands.

To give you an idea of how pipes can be useful, consider that there are times when the output you are asking for takes up more than one screen length. When this happens, the information simply flies off the screen. If your windows do not have scroll bars, you have lost the information that is no longer on the screen. Wouldn't it be nice if you could send the output of the command to some utility program which displays a screenful of information at a time.

Fortunately there is such a utility program, called more. For example, to pipe the output of ls of the directory /util to more type ls /util | more. The vertical bar (|) is the pipe. See page 18 for further discussion of using | more to see a listing one screen length at a time.

redirecting output - Pages 19-20 talk about redirecting output to a file. Read over this section, and try the following example. Type

whoami > temp

more, less & cat - Now we want to see what the file temp contains. We can do this many ways. The first way is to use more as described on page 22, or with cat as described on page 23. Try either and see what the contents of the file named temp is.

Using wildcards - Wildcard characters are used in patterns to match filenames. For example, the wildcard character ? matches any single character. Another wildcard that will be useful is the * this character, which matches multiple characters. Review page 21 for the basic use of wildcards.

man - The man command brings up a manual page (help screen) for a specified command. Let's get the man page for the finger command by typing man finger. Also try the examples given for man on pages 26-27.

Directories and files
Next is a list of some fundamental commands which allow you to manipulate and organize files in a Unix file system. Read the description of each, and carry out any exercises given.

mkdir - This command creates the specified subdirectory. Follow the example on pages 30-31 to make your own subdirectory named NewDirectory.

cp - This command copies a file to a new location, leaving the original unchanged. Type

cp NewDirectory temp

How many files does ls report now? Look at the examples on pages 34-35 for more ways to use cp.

More fun with ls - Pages 36-37 talk about the different ways you can use ls to get different information about files. Figure 2.1 on page 36 will help those who have not used Unix before understand what gets displayed to the screen when you type ls -l at the prompt.

mv - This command moves a file from one location to another. But beware, because of the way file systems work, moving a file is very similar to renaming. The mv command is also the rename command. For example we can rename the file called temp by:
mv temp notsotemp
Now you can move the file into the directory we created:
mv notsotemp NewDirectory
A directory is just a special type of file to Unix, so we can rename the directory we just created before by moving it to a new location. Type
mv NewDirectory MyDir
to rename the directory. Now type ls to see what has happened. See the examples on page 38.

rm - The command rm removes a file. Type rm -i temp followed by ls. How many files does ls report now? Read more about rm on pages 39-41.

rmdir - This command removes the specified subdirectory. Type rmdir myDir. Read pages 42-43 for more examples of removing directories.

find and ln - The sections on find and ln are interesting to read about - especially when you are looking for a file and can't remember which directory it is in. Read pages 44-50 for more information about these two commands.

Compression of Files

The zip utility is used to create zip files. To create a zip file named foo.zip of all the files in the directory named bar type,
zip -r foo.zip bar
To extract the contents of the zip file foo.zip (the directory bar with all its contents) type,
unzip foo.zip

If you do this in the same directory from which you originally created the zip file, the contents of foo will be overwritten by what is in the zip file. Chapter 13 talks about different ways to compress and decompress files. The zip utility is discussed on pages 297-298.

The command shell

Chapter 3 of the Unix book talks about shell command interpreters (often referred to as just shells). You interact with the shell when you type commands at the prompt. You should read this chapter. It is important to know that there are different shells available and understand what some of the differences are amongst these various shells. This chapter also leads nicely into Chapters 8, 9 & 10 that deal with running and writing basic programs that can work with the shell and also with configuring the shell. These topics are a little more advanced than you need for this course. When you are ready to delve deeper into the world of Unix these chapters are a good place to start.

Creating a file

Chapter 4 of the Unix book mentions two editing programs you can use to create and edit files. This semester, we will develop our Java files in an editor called Eclipse, which is an environment designed specifically for creating programs. However, it has the ability to create files that are not related to programming. (If you have Eclipse installed on a Windows machine, you can edit Word and Excel documents using Eclipse!) In this exercise we will use Eclipse to create a simple text file. In the rest of the labs this semester, we will use Eclipse to create our programs.

Exercise 1 (35%)

Do the following exercise. You will hand in the result of doing this exercise. In order for your submission to be graded correctly you must follow the instructions given precisely, in the order given, and must not do anything extra.

Create a directory in your home directory named cse115.

Change directories into that directory (using cd).

Make a directory named workspace.

Copy the skeleton files for this lab located in the directory /projects/CSE115/Skeletons/Lab1Skeleton.zip
into your current working directory (.)

When you list the contents of the current directory, you will see the directory named workspace that you just created and the file named Lab1Skeleton.zip.

Unzip the Lab1Skeleton.zip file. Notice that a new directory named Lab1 has been created by unzipping the Lab1Skeleton file.

Change directories into the Lab1 directory.

List all of the files in this directory and notice that inside the Lab1 directory are two more directories and a file named Command.txt.

Change directories into the Sub1 directory.

View the contents of the file named MyName.txt. If the file does not contain your name, you will need to edit the contents appropriately. You should use Eclipse to help you do this. You can open eclipse by typing /util/eclipse/eclipse & at the prompt. When you start up Eclipse, you will see the following screen:

Then you will see a Window that will ask you which workspace you want to open. By default, it will probably say something like this:

You do not want to use this default workspace. Use the Browse button to make the workspace point to the directory you just made named workspace, like this:

You will then see a screen that looks like this. You will choose the arrow to take you to the Eclipse workbench.

You will then see the default workbench setup. The TAs will talk about customizing this and changing it around in the next lab. For right now, we will use the workbench as it is.

We need to open the file we want to edit. Click on the File menu and then Open. Navigate to the file named MyName.txt and you will see it appear in the main section of Eclipse like this:

Click on that section to cause your cursor to appear. Erase the name that is in the file and put your name in its place. Save the file (File menu, select Save).

After you have saved your file, leave Eclipse open (you can minimize it) and go back to your prompt. (See how useful the & is). Change into the Sub2 directory by typing the cd ../Sub2 command.

Move the file named Lab1.txt directly into the Lab1 directory by using the move command and the .. (parent directory).

Open the file named Command.txt using Eclipse. Note that this file is in the Lab1 directory, not the Sub1 or Sub2 directories. In this file you will type the command you just used to move the Lab1.txt file. Save this file.

Go back to the prompt and delete the Sub2 directory.

Zip the Lab1 directory and its contents to make a file named Lab1.zip. Submit this file now that you have completed Exercise 1.

How do you submit files? In general you submit files using the submit command, which has the following format for CSE115:

submit_cse115?? filename
where `??' is your section. Your section is the recitation section of the course such as a2 or b3. The filename is the name of the file you wish to submit. Let us suppose that you are in the b2 lab section. Since you want to submit a file named Lab1.zip, you should then type
submit_cse115b2 Lab1.zip
(Of course if you are not in section b2 you need to substitute b2 for your actual lab section.)
If the submission worked properly you should get a message saying
Submission of "Lab1.zip" successful.
If you are in CSE503, you would submit to the recitation you are attending. Most of you are attending A2, so it would be submit_cse115a2.
You can also use the submit inspector on the resources page of the course web site to verify that your submission was delivered properly. If you do not get this message, ask a lab assistant for help.

Exercise 2 (12%)

Using the rm command without the -i flag can lead to disasterous results, especially if you execute the command and have a typo. Suppose you wanted to delete all files with the file extension .txt (rm *.txt), but when you typed the command, you accidently typed rm * and now you have deleted all the files in the directory, including the files for the project that is due in 15 minutes for CSE 115!

To help avoid these calamities, we are encouraging you to alias the rm command to actually execute the rm -i command. This way, the system will prompt you to ensure that you really want to delete the files you requested. You can read about the alias command on pages 190-191.

You can alias as many commands as you wish, but for the purposes of the exercise, we are most concerned with you alias-ing the rm command. You can do this by creating a .alias file using a program called gedit. To run gedit, type gedit & at the prompt. This program is a simpler text editor than Eclipse and is also available for you to use on our systems. In this file you can place any aliases that you wish to create for yourself. Save this file in your home directory (with the name .alias)

For our systems, you format your alias command like this (note that this is different than the book):

alias rm 'rm -i'

Next, create a backup of your .cshrc file by copying the file to a file named .cshrcBack. Creating a backup copy of a system file is always a good idea before attempting to modify it. This way, if you do not like the settings you changed or if you broke something, you can simply revert back to the original settings before the changes. Open the original .cshrc file and at the bottom of the file type:

source ~/.alias

Save and close the file. Next time you log into styx, your aliases will take effect.

You might also want to create an alias for Eclipse at this point. You will be using Eclipse a lot this semester and a shortcut to starting up the program is nice. You can add the following to your .alias file:

alias eclipse '/util/eclipse/eclipse &'

Now when you want to run Eclipse, you can simply type eclipse at the prompt.

Printing files

These batch of commands are useful to know when you wish to print a file to a printer. This is described in the book on page 324.

lp - The lp command is used to submit a file or a set of files to a particular printer for printing. You can use the -d switch (sometimes called 'flag') to specify the printer you want your job sent to. For example, to print a file named filename to the printers in Bell 101, type the command

lp -d bell filename

The lp command creates a print job, which is entered into the specified printer's print queue. A print queue is a list of all the jobs that are waiting to print. Jobs are order by the time at which they were placed in the print queue. A print queue works much like a queue at a bank teller.
lpq - The lpq command displays the current print queue for the specified printer. For example, the command lpq -Pbell gives the print queue of the printer in Bell 101. Try this now.

If you create a print job with lpr but you don't specify a printer, your job will be sent to a default printer. You can use the lpq command (just type lpq) to find out what your default printer is. Pay special attention to the physical location of the printer reported, so you can pick up your printouts if you send them to the default printer.
lprm - The lprm command removes the specified print job from the specified print queue. This command is useful if you decide, after submitting a job to a printer, that you really didn't want to print it after all. You will need to specify the job number of the job you wish to remove from the queue. You can find out the job number of your job using the lpq command. As with lpr and lpq, you can specify a particular printer for lprm using the -P flag.
mpage - The mpage command can be used to print a file with multiple (logical) pages on one sheet of paper. You should use this command rather than lpr whenever possible to prevent the slaughter of poor innocent trees. See the man page for details about the various options available.

Web browser

The next thing you might want to do is start a web browser. The web browser installed on these systems is Firefox. Start the firefox web browser by selecting "Applications" from the panel at the top of the screen. Then select "Internet" and then "Firefox Web Browser":

When you first start firefox, you might get a window that looks like this:
Just click on "Next >", then in the following window, click "Finish".

Navigate to the course website at http://www.cse.buffalo.edu/faculty/adrienne/SP2007/cse115, and browse around to get a feel for the types of information available to you. You are expected to check the main page of the web site for announcements on a regular basis.

E-mail

Since you have a UB-IT account (i.e. an ACSU or UBUnix account) you also have an e-mail address @buffalo.edu. You cannot receive e-mail at this account until you enable it (even though you can send e-mail from this account without needing to do anything special). You should have enabled your ACSU e-mail account before coming to your lab session. If you have not already enabled this e-mail account, do so now by visiting http://mailcluster.acsu.buffalo.edu/newuser.html, entering your UB-IT name and clicking the "Submit" button.

The CSE e-mail system is separate from the main UB e-mail system. You can choose to maintain two separate and parallel e-mail systems for yourself (make sure you read e-mail at both sites). An alternative is to designate one as your primary e-mail system, and to forward your e-mail from your secondary e-mail service to your primary. When you account was created, it automatically forwards your CSE email to your UBUnix account. If you would like to maintain two separate email accounts, just delete the .forward file in your home directory.

If you coose to maintain two separate email accounts, you can use Thunderbird to read your email. The information you will need to setup Thunderbird is located here.

Exercise 3 (13%)

Send an e-mail to the grading TA for your section. (See the table below for who your grading TA is.) Make sure you send a copy to yourself by including your e-mail address in the list of recipients in the "To:" or the "CC:" line. It is strongly suggested that you use UBUnix WebMail. The email should be received from your buffalo or CSE mail address, no other email addresses will be accepted. (Resist most strongly the urge to send a copy of this e-mail to your lecture instructor or the teaching TA that is in the lab with you now.) The subject of your e-mail must be: `CSE 115: Lab 1 your name and person number'. For example, `CSE 115: Lab 1 Frodo Baggins 13572468'.

The contents of your message should describe, in 50 words or less, why you want to take CSE 115. You should also create an attachment to this email that is the file you created named .alias that contains your defintion of the rm alias and any other aliases you wished to create. In order to do this, you must manually type in the location of the .alias file (remember it is in your home directory, so it is ~/.alias. Verify that you can read the mail once you receive it.

Recitation Section

Grading TA

A2
Lei Shi

A3
Daekeun You

A4
Daekeun You

B1
Lei Shi

B2
Daekeun You

B4
Lei Shi

Miscellaneous topics

If you wish to explore Unix further you are encouraged to read the Unix book in its entirety.

Chapter 5 deals with some of the security features implemented on Unix. It talks about how users are allowed access to some files, but not to others. This is important especially if you are creating a webpage. In order for everyone to view your page, you need to make sure that the files are readable to everyone. It also discusses groups and group permissions to files - so that everyone does not have access, but rather only those members of a specific group.

Chapter 6 deals with manipulating parts of files, and comparison between them.

Chapter 7 talks about getting information out of the system, such things like who else is on the system at the same time you are. All of these chapters have useful information in them, but this lab would get much longer than it already is if we went through every page. You are encouraged to read these chapters and learn the material in them.

Chapter 12 talks about some basic issues related to the Internet, Unix, remote systems, how to communicate with users and how to tranfer files. This book suggests using lynx to surf the web. Lynx is a text-based browser available on our systems. I would, however, strongly suggest that you use a graphical web browser instead. The only currently supported browswers on our Unix system are Netscape and Firefox.

Chapter 14 deals with installing software onto the system. At this time, you will not need to do this, all of the software needed for this class has already been installed on the system for you.

Chapter 15 talks about some handy utilities available on the Unix system, like a calendar (we have a graphical version called xcalendar; also useful is plain old cal), a calculator (we have a graphical calculator named xcalc), spell checkers, and history keepers. This is a valuable chapter for making working with Unix more enjoyable.

Chapter 16 talks about system administration by being logged in as root. You can only log in as yourself on our systems.

Chapter 17 talks about some more advanced Unix tricks that are nice to know, such as mail sorting and multiple file replacement.

Appendix A is a recap in short tabular form of all the commands discussed in the book - a good quick reference guide.

Appendix B talks about the main file structure for a Unix system.

Appendix C gives a list of many Unix commands and the flags that can be used on them. It also gives a description of what all of those things do. For example, in the command ls -l, the -l is called a flag (or option) on the ls command.

Use the Tools You Have Been Given

One of the most important lessons that you can learn as a computer scientist is how to make the resources available to you, work for you. The same is true of the resources of this class. Information is always given during lectures and recitations and you are most strongly encouraged to attend all lectures and recitations throughout the semester. There is a wealth of information available on the course website to help you with the material of this course.

Another resource that is available to you is the staff of the course, which includes both the instructors and the teaching assistants. There are office hours available at many times throughout the week for you to go and receive extra help on an assignment or simply have some questions answered about the week's material. No appointments are needed to come to office hours.

Exercise 4 (20%)

To ensure that you will be able to use the resources of this course, you will spend some time this week visiting office hours. You will also use the resources of this website to help you on your journey. First, follow this link to find the Lab 1 attendance form. You should print out the form. Follow the directions on the form to complete Exercise 5. This form is due to be handed in at the beginning of your next recitation section. Note that the electronic portions of this lab are due to be completed by 11:59pm the night before your recitation meets next week. To qualify for early points, all of the electronic portions must be handed in early - the attendance form can only be handed in at your next recitation.

Exercise 5 (20%)

Another resource for this course is the CSE Mentoring program. You have met the mentors for your lab section today. You must email one of them and give them a list of free times that you have during the week so they can schedule mentor meetings for times that are available for all of you. Please include available times for each day (Monday - Friday) from 8:00am until 9:00pm. You will be required to attend the first meeting with your mentor as part of next week's lab, so please make sure that the times you list are available times for you. The email should obviously include your name and which recitation section you belong to. The subject of your email should be:

[CSE MENTORING] My availability: Your name

with Your name filled in appropriately. You should have received email addresses for the mentors for your section in lab this week.

Due dates

You have one week from the meeting of your lab to submit your solution. For example, if your recitation meets on Wednesday, January 24^th then you must submit the lab by 11:59 pm on Tuesday, January 30^th. The due dates are summarized in the table below. If you submit more than once, the later submission will simply overwrite the previous one.

Date of lab	Due date for electronic submission
Tuesday, January 23	Monday, January 29
Wednesday, January 24	Tuesday, January 30
Thursday, January 25	Wednesday, January 31
Friday, January 26	Thursday, February 1