Frequently Asked Questions

• FAQ01: How do I get help if my question is not in this list?
• FAQ02: How do I get a UNIX account for my course?
• FAQ03: How do I get a PC account in the lab?
• FAQ04: How do I check my disk usage?
• FAQ05: How do I avoid trouble from disk quotas?
• FAQ06: How do I log on to CS networks from off-site?
• FAQ07: How do I transfer files to/from my PC?
• FAQ08: How do I create my homepage?
• FAQ09: How do I choose a good password?
• FAQ10: How do I write a CGI script?
• FAQ11: How do I get an alumni account?
• FAQ12: How do I find someone's email address?
• FAQ13: How do I print?
• FAQ14: How do I use remote (IMAP/POP) mail service?
• FAQ15: How do I fix my vt100 windows?
• FAQ16: How do I get a file restored from backup?
• FAQ17: How do I keep from losing my important files?
• FAQ18: Math and CS anti-spam
• FAQ19: Can I use my laptop in the UNIX lab?
• FAQ20: Is there wireless access in the UNIX lab?

FAQ01: How do I get help if my question is not in this list?

Last modified: 2011-07-26

FAQ02: How do I get a UNIX account for my course?

1. Steps to Run Apply Procedure - Two options:
   1. From a SunBlade: Don't use the regular login box. Instead get a "console session" login (simpler and faster than XWindows): select "Options", "Command Line Login" and see text. Press 'Return' key once or twice if text does not appear, and see text. At 'login' prompt, type "apply" and press 'Return' key, see next line. At 'password' prompt, type "apply" and press 'Return' key, and follow instructions on the screen (remaining prompts are explained in steps given below).

      OR

      Remotely: Run ssh to access host "apply.cs.umb.edu" via port 22 or port 80, log in as user "apply" with password "apply", and follow instructions on the screen (remaining prompts are explained in steps given below).

      For both options, logging in as the apply dummy automatically runs the apply program.

      WARNING: Do not use the arrow keys to erase typing errors. Use the delete key or wait until the end of the process to correct them. You will have a chance to review and possibly re-enter your information.

   2. You will be asked if you already have a UNIX account, meaning an account on any CS Department computer. If you have an account, use your existing username to avoid problems. If you are not sure if you have an account, or if you forgot your password, see an operator in room S-3-157D.
   3. If you do not already have an account, you will be asked to choose a username. Usernames can be between two and eight characters. Your username MUST be all lower case letters or lower case letters and numbers and should start with a letter. We strongly suggest that you use the first letter of your first name, followed by the first 7 letters of your last name. For example: "jmcnama'' for James McNamara. If someone else is already using what you typed, you will see a message about it. Choose again. Our example James McNamara might use: "jmcnam2".
   4. You will be asked for your real name as on the class roster. Please type it in using uppercase and lowercase letters in natural order. For example, enter "James Q. McNamara" not "McNamara, James Q.".
   5. You will be asked what password you want. Click here for how to choose a good password. Passwords are checked periodically by a program that tries all the dictionary words and additional "easy" passwords such as "xyzzy" or nicknames. Accounts that fail the password check will be disabled temporarily, so make up a good password at the beginning.
   6. If you are applying for a new account, apply will ask you to choose a type of account: choose undergrad or grad. Please advise operator by mail if you ever change from ugrad to grad, or whatever.
   7. Apply will now ask you to select the name of the course and instructor you are applying for; type in a number of an item from the list, 1-18 (or so). The program builds a list of courses you want to add; you may choose more than one course. When you have no more courses to add, type 'q' for "quit" in place of a number.

2. NEW ACCOUNTS ARE NOT ACTIVATED UNTIL YOU SHOW ID TO THE OPERATOR! Applying for an account just queues up a request. Accounts do not get created automatically; a person approves them by running a 'reply' script, which actually creates accounts.
   1. Show ID to the Operator in the UNIX Operations Room (S-3-157D). Students without a UMB student ID can use their license or passport along with their bill. We accomodate off-campus courses by having the instructor furnish us with a list of names to approve.

3. Operators run the Reply script. You should receive the account and/or course software you applied for in a few hours.
   1. Test if a new account exists by trying to login. Do so by sitting at a SunBlade in the lab, or by ssh to users.cs.umb.edu. Test if you have course software by looking in your UNIX home directory for a link with the coursename.
   2. If you do not have an account and/or course software after a few daytime hours, go to the UNIX Operations Room (S-3-157D) and find out why. Do not run apply again unless the operator asks you to. If you get an account but it has problems, send mail to operator or go visit ops.

      IMPORTANT: Never share your password with ANYONE. We mean it. We have a strict one-account, one-user policy. We can help you communicate with other systems and share group files without sharing passwords. If you share your password you might lose your UNIX account.

FAQ03: How do I get a PC account in the lab?

1. After the class group is formed, the lab operator will set up student accounts on the lab PCs for students in the group, using names that are the same as on UNIX. We will inform the instructor of a common default password for the class to use for their first login only.

2. During the first logon session, students will have to change their account's password to a good one of their own. From then on only their new password will work for them.

3. UNIX home directories and printers are shared to PCs using samba.

3.1. To get a samba account, students should see the operator on duty. You will type in your password yourself without having to disclose it. For harmony, your PC username will match your UNIX username, and the samba password you set will be the password you use to log in to your PC. [Windows caches those credentials and offers them automatically when it mounts shares from file servers. Thus, opening your UNIX home will not stop to make you type a username and password into a pop-up window.]

FAQ04: How do I check my disk usage?

2. It is very efficient to use the results of overnight du runs that are stored.

The script ~operator/bin/DU mimics the du command, but uses the output of the overnight du runs instead of walking the tree in real time. It is a goof in perl; anyone who wants to copy and modify it to do better is welcome to do so. Mail sysprog about it.

Recall that the file contents are static and only reflect the tree as it was at 05:00 or so today.

FAQ05: How do I avoid trouble from disk quotas?

Note that disk space is provided separately for CS courses and PhD research, so that stuff doesn't count against home usage.

1. HOMES

All student homes must use less than 200 Mb of disk. All alumni homes must use less than 50 Mb of disk. The lab directors may refine their policy on quota values (up or down), at any time.

2. MAILBOXES

All student mailboxes must use less than 2 Mb of disk. In the mail spool, we will impose on students a soft quota of 2 Mb, and a hard quota of 5 Mb. That means you will be warned if you go over 2 Mb, and that your mail will bounce if you go over 5 Mb. If necessary, ask an operator how to save mail under your home, or to your PC.

3. THE QUOTA MECHANISM

There are two limits associated with each user, per filesystem: the soft limit and the hard limit. When usage exceeds the soft limit, you see messages to reduce usage. When usage exceeds the hard limit, you cannot write to your files. The system will not allow a user to exceed his or her hard limit. However, a system administrator may set a soft limit (sometimes referred to as a quota) which can be temporarily exceeded by the user. The soft limit must be less than the hard limit.

Once the user exceeds the soft limit a timer begins. While the timer is ticking, the user is allowed to operate above the soft limit but cannot exceed the hard limit. Once the user goes below the soft limit, the timer gets reset. However, if the user's usage remains above the soft limit when the timer expires, the soft limit is enforced as a hard limit. By default, the softlimit timer is seven days. The value of the timer is shown by the timeleft field in the quota command.

For example, let's say a user has a soft limit of 10,000 blocks and a hard limit of 12,000 blocks. If the user's block usage exceeds 10,000 blocks and the timer is also exceeded (more than seven days), the user will not be able to allocate more disk blocks on that file system until his or her usage drops below the soft limit

You can check you quota status with the command quota -v. Note that the filesystem names will not exactly match the paths like /home/username that you are used to seeing, because we use the automounter. The relation between your home and which filesystem it is in is declared in /etc/auto_home. If you are not sure ask an operator.

4. REDUCING DISK SPACE USAGE

It is a big win to compress text files with gzip. See `man gzip`. Also, you should be copying files out to your PC and burning your own archive disks and such.

5. IF YOU ARE OVER QUOTA

At login time, before /etc/motd is displayed, you may see a message from the quota command about being over and having to reduce your usage by so much. You can see that any time by running the quota command. If you are over your hard limit and cannot write into your home or mailbox, recall that each host has a /tmp directory where you can do scratch work. This can help you examine archives or compressed files that you cannot uncompress in your home. Also recall that your mailbox is an ordinary file, /usr/spool/mail/$USER that you can copy from and to. Thank you for your cooperation towards fairness and better service for all.

FAQ06: How do I log on to CS networks from off-site?

FAQ07: How do I transfer files to/from my PC?

FAQ08: How do I create my homepage?

FAQ09: How do I choose a good password?

• any part of your name or name+initials or name+date
• any part of any name found in the password file
• names or words that are backwards
• words with mixed capitalization (NoTHarD)
• words with cute misspellings (WarezD00D)
• words with a single digit added (like "pascal1")
• words with substituting "1" for "i" or "0" for "o" (M1ll10n)
• two small words put together (badbad, baddab)
• strings that are all numbers (123321)
• short or repeating nonsense words ("glup" or "frgfrg")
• acronyms or scrambled words (umbcslab, aajv011)
• any systematic, well-adhered-to algorithm whatsoever (for example, suggestions patterned after
something in a book)

Examples of bad passwords (modified from the Security FAQ):

• alec7 - it's based on the users name (& it's too short anyway)
• tteffum - based on the users name again
• gillian - girlfiends name (in a dictionary)
• naillig - ditto, backwards
• PORSCHE911 - it's in a dictionary
• 12345678 - it's in a dictionary(and people can watch you type it easily)
• qwertyui - ...ditto...
• abcxyz - ...ditto...
• 0ooooooo - ...ditto...
• Computer - just because it's capitalized doesn't make it safe
• wombat6 - ditto for appending some random character
• 6wombat - ditto for prepending some random character
• merde3 - even for french words...
• mr.spock - it's in a sci-fi dictionary
• zeolite - it's in a geological dictionary
• ze0lite - corrupted version of a word in a geological dictionary
• ze0l1te - ...ditto...
• Z30L1T3 - ...ditto...

FAQ10: How do I write a CGI script?

1. Make a script or program that prints good, legal HTML to its STDOUT. You should run your program under the shell and check its output before wiring it up into your home page. Until it gives good output you'd be wasting your time fooling with having the web server call it. Run weblint against it.

2. Refer to your program by way of our CGI server. For example, "http://cgi1.cs.umb.edu/~username/myprog.cgi". That hostname cgi1 is an alias for a box with a web server that can see your home page and is configured to run CGI programs. We don't allow CGI to run on the main web server. That is so that in case some program goes nuts it won't drag down the whole site.

3. The error log of the httpd on cgi1 is /data/httpd_logs_cgi1/error_log. Users may read that file in pursuit of their errors.

4. CGI scripts can introduce security holes or be CPU hogs. Please be very careful in using them: follow a good cookbook and do not "give away the store." Thanks.

FAQ11: How do I get an alumni account?

If your account is currently shut off, we will re-enable it while you either (1) apply for an alumni account as below, or (2) copy out your files before the account is deleted. Please advise us which you will do, by sending email to operator(at)cs(dot)umb(dot)edu.

Alumni accounts must be authenticated, and have a valid address. We invite and require you to authenticate yourself by U.S. Mail. Please mail us a photocopy of your driver's license (in lieu of National ID Card), or your passport or some official picture ID. You should obliterate your SSAN, as we don't want to know it.

Mark your photocopy with (1) your login name, (2) the date and type of degree you received from UMass Boston, and (3) your current U.S. Mail address. Mail to:

Computer Science Alumni Sysadmin
UMass-Boston
100 Morrissey Blvd.
Boston, MA 02125-3393

We will keep your info OFF-LINE, but may share it with the Alumni Office so they can beg you for money.

The lab directors have required authentication since Nov. 1, 2002. Users who registered have valid login shells. Other old friends do not, and unused accounts get deleted routinely. Please keep your account active by logging in to alumni.cs.umb.edu at least every quarter-year, and keep your mailbox small. Thank you!

FAQ12: How do I find someone's email address?

FAQ13: How do I print?

lpr myfile.c

You can specify the printer name with -P flag - like so: lpr -Plj2 myfile.c

To save paper, use the mpage utility - like so:

mpage -xUH -Plj2 myfile.c

If you replace 'x' with the number 2, it will print two regular pages onto one.

mpage -2UH -Plj2 myfile.c

Please look at the man page for more info:

man mpage ...

2. To see what is in the queue:

lpq (or lpq -Plj2)

You should see something similar to the following:

  Printer: lj2@v1 'HP LaserJet 8150DN located in S-3-157A'
  Queue: 1 printable job
  Server: pid 2637 active
  Unspooler: pid 2638 active 
  Status: processing 'dfA222ulab.cs.umb.edu', size 845, format 'f', 
      IF filter 'ifhp' at 20:55:17.490
  Filter_status: getting end using 'pjl job/eoj' at 20:55:21.456
  Rank Owner/ID Class Job Files Size Time
  1 eoneil@ulab+222 A 222 myfile.c 845 20:55:14

3. To remove a print job from the queue, type "lprm" followed by the job number associated with your file, in this example 222. (see above)

lprm 222 (or lprm -Plj2 222)

When you pick up a job at the printer make sure to take only your own output. Anything else you find there you should stack neatly.

FAQ14: How do I use remote (IMAP/POP) mail service?

Our POP server is at pop.cs.umb.edu.
Our IMAP server is at imap.cs.umb.edu.
Our SMTP server is at smtp.cs.umb.edu.

Please use these aliases as they are guaranteed to work.

Our SMTP server only handles outbound mail for clients on our LAN. Please do not configure your client to use it from home, unless our postmaster has told you to do so: your mail will be refused, and the log messages are annoying. If your internet connection is through an ISP, please use their SMTP server for your outbound mail. If they don't offer one, get another ISP. We might make an exception in an extreme case, but we haven't had to yet, since all ISP's so far have SMTP servers.

FAQ15: How do I fix my vt100 windows?

echo $TERM

That should agree with your ssh client. If not, you can tell UNIX the terminal type being emulated, so:

set TERM=vt100

If you check your ~/.login file, you will see a section where the terminal type gets set. If that code isn't getting your terminal type set correctly for you, you can comment it all out and replace it with one or more simple declarations that do.

Messy output

On some UNIX systems, the default behavior for tabs is to print them literally. If you see output all messy, tabs may not be agreeing with your terminal emulator. The command

stty -tabs tells UNIX not to send literal tabs, but to expand them into a bunch of space characters. You can put that into your .login file if it works for you and you want that all the time. Window Size UNIX assumes a vt100 is 24 rows x 80 columns. If you like a larger window, you can adjust UNIX's notion of its size with the script /usr/local/bin/fix.vt100. It takes an argument that is the number of rows (lines) in the window. For example,

fix.vt100 35

fixes up a vt100 for 35 lines. The fix.vt100 command is a "self-documenting Bourne shell script."

FAQ16: How do I get a file restored from backup?

For current work, including course directories:

1. The name of the file.
2. What directory the file was in.
3. When you last edited the file, or saw it in good condition. Yesterday, last month, etc.

An operator will restore the file(s) into the directory RESTORE under your home, usually by the next day. Please recover from there what you need, and delete what you don't.

For old course directories:

1. The course number.
2. What semester and year you took the course
3. The instructor's name.

An operator will restore the file(s) into the directory RESTORE under your home, but please note that old work is done at low priority. Please copy out and then delete restored course dirs. Make your own archives to keep at home.

FAQ17: How do I keep from losing my important files?

1. SHORT TERM

Backups are usually done around 00:30. A file created during the day and deleted shortly thereafter is GONE. We cannot restore it. You might copy very critical course files to your home, since homes and courses are generally on different disks. You might use a script to copy a file to your home before you edit it, like many examples to be found on the net.

2. LONG TERM

You should be copying files out to your own PC and burning your own archive disks and such. Your home, web page, homework, etc. The zip command makes nicely portable, compressed archives. We routinely trash old semester trees to make room for new classes, so clean up and copy out the stuff that is precious to you. Do it on some schedule but especially at the end of semester.

FAQ18: Math and CS anti-spam

1. Systems Use Realtime Blackhole Lists (dnsrbl)

   Please know that we have recently become very much more aggressive in our anti-spam measures. In particular, the mail daemons on the math and cs mail servers now decline to accept mail from hosts that are listed as bad guys by spamcop or spamhaus. Please see:

       http://www.spamcop.net
       http://www.spamhaus.org

   We now drop over 50,000 connections per day, drastically reducing the number of messages to be scanned for virus and spam.

2. SpamAssassin 'spamd' Deployed

   We now have spamd running on three of the new SunFire 4200's under linux. There is a local script to invoke the spamc client side, and the prototypical .procmailrc file is updated to use it.

   Under the old setup, and for the near future, SpamAssassin is invoked by the sytem on each message that comes in. That sub-optimal method will be dropped about as soon as we can suppose that everyone has changed over to spamc/spamd.

3. New Prototypical Procmailrc File

   If you already have a procmail filter set up, then you will want to merge it with, or replace it with, the latest recommendation. Please see /usr/local/lib/.procmailrc.

   If you do not have a procmail filter yet, you may install one by doing the following actions in the shell.

   N.B.: You should review the procmailrc file *before* setting up your .forward file.

   cd
   mkdir -p .procmail
   mkdir -p mail
   cp /usr/local/lib/.procmailrc .
   echo '"|/usr/local/bin/procmail #'$USER'"' \
          > .forward
   chmod go-w .procmail .procmailrc .forward
   

   At this point your .forward should contain, for example, "|/usr/local/bin/procmail #rickm" -- including the double quotes and your username after the #.

   New mail will be sorted into one of the files mail/spam.* or your system mailbox. If you want to be conservative initially, you can see where to change the code to save even high-score spam.

   You will want to watch your ~/.procmail/log file to be sure that things are going as expected. Once you are comfortable, you will want to turn off verbosity in the .procmailrc file.

   Please report bugs by email to operator.

FAQ19: Can I use my laptop in the UNIX lab?

Yes, there are some empty workstations in the terminal room, S-3-157, by a wired switch.

Please email operator(at)cs(dot)umb(dot)edu from your lab account to tell us its MAC (ethernet) address. We will enter that into our DHCP server's table of good guys, and you will be able to get an address.

FAQ20: Is there wireless access in the UNIX lab?

Only at some places, particularly the web lab S-3-028.

The web lab has in it a WAP that is the same as the ones in the Campus Center. Details are available in that room, posted below the WAP. Your prof will tell you about any others that may be set up to support their research and instruction.