Brandeis University Computer Science - Systems Operations

Frequently Asked Questions

Please read these frequently asked questions before e-mailing guru.


If you're unsure of a command, you can type in man cmd at the prompt, where cmd is the name of the command. Try typing man cd or man ls or man rm at the prompt.


Note: If you'd like a hard copy of these instructions, click on File in the upper left hand corner of your screen. Then click on Print. Click on Ok.

While this page is updated occasionally to correct or remove answers no longer accurate or relevant to the computer science department systems, it is worth noting that this document has been around for a long time, and may make references to things with which you are not familiar. If this makes you feel frightened or lonely, try drinking a warm cup of tea, or use google until the feeling passes.


    Accounts
  1. What is a CS Account?
  2. How do I get a CS Account?
  3. How do I change my password?
  4. I tried to log in and received the message "Your account has expired; please contact your system administrator." What does this mean? What should I do?
  5. I have a friend who doesn't have a cs account. Can I let him/her use mine?
  6. I forgot my password, or it expired because I didn't change it within the last year. What can I do?
  7. How much space do I have on my cs account?
  8. How do I protect my files?
  9. I think someone has my password. What do I do?

  10. The Berry Patch
  11. What is the Berry Patch?
  12. I need to leave the Patch. Do I have to logout?
  13. How do I print out to the printers in the Patch?
  14. How do I use the scanner in the Patch?

  15. SSH, SFTP, Connecting etc.
  16. Where can I plug my laptop into the network?
  17. How do I remotely login to a computer?
  18. Why is rsh not working?
  19. What is FTP, and how do I use it?
  20. What happened to the FTP server?
  21. What is SFTP, and how do I use it?
  22. What is SCP, and how do I use it?
  23. What is SSH, and how do I use it?
  24. How can I get to my files in my CS account from home?
  25. How can I get to files on my UNET webspace from a department Linux machine?
  26. Why is the machine I'm on so slow?

  27. Mail
  28. How do I set up my cs account to forward my mail to another e-mail account?
  29. How do I read my email?
  30. How do I filter my email?
  31. How do I send mail with Thunderbird or Eudora or Outlook (or another third-party application)?
  32. How can I get a new program installed?
  33. Bill Gates is promising me a trip to Disneyworld. How can I mass-forward nifty chain letters? What do I do with chain letters?
  34. How do I switch from ELM to Mutt without losing my aliases?

  35. Questions About Applications
  36. How do I use emacs?
  37. How do I use vi?
  38. How do I use the UNIX operating system (the operating system on most of the machines in the Patch)?
  39. Where would I find java in the Berry Patch?
  40. What do I do with .pdf files?
  41. What do I do with .ps files?
  42. How do I read newsgroups on the Macs in the Berry Patch?
  43. What Mac software is available for use on the Berry Patch systems?

  44. CS Webpages
  45. Where do I put webpages? How can people see them?
  46. How do I password protect my webpages to allow limited access?
  47. How often are the files in my home directory backed up?
  48. How often are my web pages backed up?
  49. Where's my cgi-bin directory?

  50. Assorted
  51. It's 9 pm on a Sunday night, and I really really really need help from a guru. What do I do?
  52. There's something wrong with a program/computer/printer. What do I do?
  53. How do I manage printers and print jobs?
  54. I minimized a window and now I can't find it. Where did it go?
  55. I tried to start Firefox, Mozilla, or Seamonkey, but got an error message saying that it's already running, and I don't have it open. What's going on?

  1. What is a CS Account?

    A CS account, or Computer Science account, is an account that you can use to log into and use computers maintained by the Brandeis Computer Science Department. It is required to get access to the Berry Patch.

  2. How do I get a CS Account?

    To have a CS account, you must either be enrolled in a CS class, be a declared CS major or minor, or be an officially affiliated postbac or grad student, postdoc, or staff member/department employee. If you meet one of these requirements, just come to the Guru office in Volen 125. You will need to fill out a form and get your advisor or course instructor or to initial it (undergrads and non-CS grad students). New graduate students, staff/employees, and others will be told whom to see when signing up for an account.

    Please already have a username and password already in mind when you come to create your account. The username must be between three and eight characters, starting with an alphanumberic character, and must be unique. The password must be at least six characters and must contain at least one non-alphabetic character. Also, appending or embedding a number to "regular" words or names is not acceptable. Your CS email will be <cs-username>@cs.brandeis.edu.

  3. How do I change my password?

    You need to login to password.cs.brandeis.edu and run the 'passwd' command.

    You will then be prompted to type in first your old (current) password (to authenticate), then your desired new password, then your desired new password once more to confirm. No characters will be echoed to your terminal as you type in either your old or new password. Hit enter after you have typed in each password. If you enter your existing password incorrectly or if your desired new password fails to pass the automatic strength checks, an alert will be written to standard error.

    Please note that password.cs.brandeis.edu only acccepts logins over ssh, and that it only accepts ssh connections from machines on the CS network (eg: public and private managed workstations and servers). Therefore, if you are outside the CS network (eg: on a laptop on Brandeis wireless, elsewhere on campus, or off campus altogether), you will need to connect through a machine on the CS network. For a list of machines available via ssh, see the public workstations page.

    Alternatively, the command 'passwd' on any cs local host should explain this to you, and redirect you to password.cs.brandeis.edu. If this does not happen, please email guru with the machine on which you ran the command, and the date and approximate time that you ran it.

    The password change should take effect on all managed machines at or shortly after the top of the hour (eg: 10:00, 11:00, 12:00, ...).

  4. I tried to log in and received the message "Your account has expired; please contact your system administrator." What does this mean? What should I do?

    If either your account OR your password has expired, our linux machines will deny access with the message "Your account has expired; please contact your system administrator." As such, if you receive this message, it means one of two things. Either: a) Your account has expired, or b) Your password has expired.

    If your account has expired, contact guru and let us know what CS class(es) you are in this semester or, if you are a declared CS major, who your adviser is.

    If your password has expired, see our password reset instructions.

    If you are unsure whether it is your account, password, or both which have expired, contact guru and ask.

  5. I have a friend who doesn't have a cs account. Can I let him/her use mine?

    Nope. The only thing you can achieve is to lose your account as well. People caught sharing account will have their account suspended and, in case of repeated offense -- disabled.

  6. I forgot my password, or it expired. What can I do?

    Passwords must be changed at least once every 365 days or sooner. If your account password is not changed within that time, it will expire.

    If you have forgotten your password, or it has expired, stop by the guru office with a photo ID (we accept IDs issued by: Brandeis University, the state of Massachusetts, and the United States Federal Government), and ask a guru to change your password. The System Operators can change your password, but they DO NOT know what your password is.

    Please note that, as email is an inherently insecure form of communication, we will not perform password resets via email. As such, please do not ask for an email-communicated reset, and please do not send us Personally Identifying Information (eg: US Social Security Number, Brandeis Student ID Number, etc) via email. We cannot accept such information as proof of identity, and you only place yourself at risk of fraud ("Identity Theft") by sending it over the public internet in the clear.

    Faculty and staff who require emergency password resets but are unable to come to Volen 125 in person (eg: if traveling away from the University) should contact the guru office for assistance.

  7. How much space do I have on my cs account?

    Undergraduates have 30 MB of disk space.

    Graduate students are not on a specific quota, but are asked to keep their disk usage reasonable.

    To find out how much space your directory is taking up right now type 'cd; du -sm'. This will summarize what you're using, in MB. The web directory has a separate "hard" quota of 7.5MB or 1500 files. The hard quota implies that you can not store more than your quota in web directory even temprarily, in contrast to your home directory where it's generally allowed on temporary basis.

    More detail in the policy.

  8. How do I protect my files?

    All files and directories have permissions on them which describe who is allowed to do what with them. You can see the permissions on a file or folder by running ls -l. Permissions have have a form of 10 character string that is grouped as follows:

    • The first character describes what the item is. Files are marked with -, and directories are marked with d.
    • The next three characters (2 through 4) correspond to permissions for u, the user who owns the item.
    • The next three characters (5 though 7) correspond to permissions for g, the group that the item belongs to. These permissions apply to users who are members of the item's group, but do not own the item.
    • The last three characters (8 through 10) correspond to permissions for o, for "other" or "world." These permissions apply to everyone else.

    Except for the item description character, each set of three characters is organized in the same way:

    • The first character is r if reading is allowed, or - is reading is not allowed.
    • The second character is w if writing is allowed, or - is writing is not allowed.
    • The third character is x if executing the file is allowed, or - is executing the file is not allowed.

    For files, these permissions are fairly self explanatory: read allows you to read the file, write allows you to edit the file, and execute allows you to run a file (like a shell script). For directories, read allows you to see the contents of the directory, write allows you to create and delete files in the directory, and execute allows running programs (including a web browser) to access the files in the directory.

    Keep in mind that even if you disallow someone from editing a file by denying them write access, if the directory allows them write access, they can read the file, copy its contents, and then delete and recreate the file with whatever permissions they desire. If you deny write access to a directory, but allow write access to the parent directory, they can delete and recreate the whole directory in the same way. Be careful with who you give write access to!

    To change permissions on a file or folder, use the command chmod <mode> <file>, where <mode> is how you want to change the permissions, and <file> is the file or folder whose permissions you want to change. To describe to chmod how you wish to change the permissions of the file, you can either describe only the change you wish to make, or describe the permissions for the file as a whole.

    To describe just the permission change, the mode will be a character representing the group you want to change (u for user/owner, g for group, o for other/world, or a for all three) followed by a character representing how you want to change the permission (+ to grant the permission, - to revoke it), followed by a character representing the permission to change (r for read, w for write, x for execute). For example, to remove write permissions for other on a file, the mode is o-w, while to add execute permissions for everyone, the mode is a+x. You can also combine multiple groups and and permission settings in one mode: to add read access for user and group, but not other, you the mode is ug+r, while to remove write and execute permissions for other, the mode is o-wx.

    To describe the permissions for the file as a whole, we use a number, instead of a string of characters. Each permission type is assigned a number: read is 4, write is 2, execute is 1. The mode we will use is a set of three sums, one for each permissions group. For example, let's say we want user to have read, write, and execute access, group to have read and execute access, and other to have read access only. The sum for user is 4+2+1=7, the sum for group is 4+0+1=5, and the sum for other is 0+0+1=1, so the mode is 751.

  9. I think someone has my password. What do I do?

    Change your password immediately and send mail to guru and chris.

  10. What is the Berry Patch?

    The Berry Patch is a computer cluster in room 119 of the Volen building. It contains several public workstations running Mac OS X and Red Hat Enterprise Linux (RHEL). It is open all the time, and the computers are always on. These computers are to be used for homework and projects. You should be given specific instructions depending on what programming language you use in your class. Anyone with a CS account can use any of the public workstations at any time, either in the Berry Patch or by remotely connecting to these computers using SSH.

    The door to the Berry Patch is locked, and you need to swipe your ID card to get in. In order to get your ID card encoded so the door will let you in, get a CS account and ask the Gurus about getting into the Patch.

  11. I need to leave the Patch. Do I have to logout?

    You don't have to logout if you're leaving for a short period of time, but you do need to lock your terminal before leaving it. To do so, you can set your screen saver to activate automatically and require a password to unlock (good), and/or lock your screen manually before leaving it (better).

    To configure your screen saver:

    • In Gnome, from the taskbar select System → Preferences → Screensaver. Use the slider to select a value for "Regard the computer as idle after" (suggested: 5 minutes, or less), and select the "Activate screensaver when computer is idle" and "Lock screen when screensaver is active" checkboxes.
    • In KDE, right click on the desktop, click configure desktop, and select screen saver from the panel on the left. Select the "Start automatically" and "Require password to stop" checkboxes, and use the up/down arrows to set appropriate time values for each (suggested: 5 minutes or less for activation, 1 second until password required).
    • In Mac OS X, from the menu bar select Apple menu → System Preferences... → Desktop & Screen Saver → Screen Saver. Use the slider to select a value for "Start screen saver" (suggested: 5 minutes, or less). You can also configure "Hot Corners" to activate or disable the screen saver at will by clicking on the "Hot Corners..." button in this preference pane.

    Because someone else could potentially take over your session after you leave your workstation but before your screen saver has time to activate, we strongly suggest that you lock your screen manually before walking away from it.

    • You can lock your screen at any time by going to KMenu (in KDE) or Actions (in GNOME) and clicking on lock screen or lock session, or by using "Hot Corners" to activate your screen saver on Mac OS X.
    • You can place a Lock/Logout padlock icon in your panel in KDE by right clicking on the panel and selecting Add > Applet → Lock/Logout Applet from the drop-down menu.
    • You can do the same in GNOME by right-clicking on the toolbar, selecting "Add to panel" and choosing the Lock screen and/or Logout icons from the list of available options.
    • In Mac OS X open /Applications/Utilities/Keychain Access.app, from the menu bar select Keychain Access → Preferences... → General, and select the "Show Status in Menu Bar" checkbox. This will place a small padlock icon in your menu bar, from which you can select "Lock Screen" to lock your screen at any time. This is the recommended method of locking your screen in Mac OS X.
    • If you are logged into a linux tty/vterm (ctrl alt F1-F6), you can lock your console with the vlock(1) command.

    Note that you should only use screen saver for a short period of time (10 minutes or less). Please be sure to save your files before using screen saver. Very often people walk in to the lab and reset the X server, logging you off and destroying any unsaved work.

  12. How do I print out to the printers in the Patch?

    The default is the HP4250 laser printer mcnally, which has a 400 pages/user/semester quota, more details in printer policy. To print a file to mcnally, use this command:

    lp -d mcnally -o duplex <filename>

    The printing system will determine the type of file automatically. Duplex means double sided, and is the default. If you need to print single sided, use noduplex, but we encourage you to print double sided to save paper. To see more print options, run man lp. All of the jobs that are sent to mcnally are queued on the print server.

    If you're having problems managing printers and print jobs, point your browser to port 631 on the CUPS print server for the printer you wish to manage. For mcnally, this is printing:631. For other printers, ask Guru for the name of the print server. From here, you can view the status of printers, cancel jobs, and so forth. Check here if a printer is not working, or to cancel a job in the queue.

  13. How do I use the scanner in the Patch

    First, make sure that the scanner is on. (The power buttons is on the front.) Next, open ImageCapture.app in the /Applications folder. Click "Overview," then select which section of the image you wish to scan by dragging the selection box. Click "Scan." When the scanner is finished scanning, you image will be in ~/Pictures.

  14. What Mac software is available for use on the Berry Patch systems?

    Brandeis has licensed a number of Apple applications for use on university-owned systems. As of fall 2010, this includes current versions of iLife and iWork. These applications can be installed on any of the Berry Patch workstations, if they aren't already; ask the Gurus for details. Please note that this software is not licensed for use on student-owned systems or any privately-owned systems; we cannot and will not install it on computers not owned by the University.

  15. Where can I plug my laptop into the network?

    In the lounge adjoining the Berry Patch there are four ethernet ports availible for laptops. To use them you will need to set your TCP/IP connection to DHCP, so that you will be automatically given an IP address (this is default on most machines).

    You can also connect to the campus-wide wireless network. For more information see here.

  16. How do I remotely login to a computer?

    You can remotely access other computers over the network using SSH. Please see below for more information on SSH. Previously, people used telnet for remote access: however, telnet is an insecure protocol, and is no longer supported.

  17. Why is rsh not working?

    Don't use rsh - use ssh instead. ssh does the same thing as rsh, but in a much more secure manner.

  18. What is FTP, and how do I use it?

    FTP stands for "File Transfer Protocol," and it is designed for transferring files between computers. However, plain text FTP is inherently insecure, and so we have turned it off. To transfer files between computers, please use either SFTP or SCP.

  19. What happened to the FTP server?

    FTP is turned off on all department machines, and has been for the past few years. If you have suddenly discovered that your file transfers are no longer working, it may be because the machine you were connecting to is down. Try using SFTP or SCP to connect to any other machine in the list of public workstations.

  20. What is SFTP, and how do I use it?

    SFTP stands for "Secure File Transfer Protocol," and it is the successor to FTP. It is used to transfer files between computers. SFTP comes installed with Linux and with Mac OS X. You can install SFTP on Windows using PuTTY, and on Mac OS 9 using MacSSH.

    To use SFTP, you can use either a command line interface, or a GUI. For the command line, you're probably better off using SCP, but to see how to use SFTP, use man sftp.

    For the GUI, you have several options, depending on what system you are running. If you are running Windows, you can use the SSHSecureShell program distributed by LTS, or you can use PuTTY, WinSCP, or FileZilla, all of which are free and open source. If you are running Mac OS X, you can use Cyberduck or Fugu, which are both free and very good, or you can use Transmit, which costs money. If you are running Gnome on Linux, you can use the Nautilus file browser (File→Connect to Server…, select SSH from Service Type). If you are running KDE on Linux, you can use KFTPgrabber.

  21. What is SCP, and how do I use it?

    SFTP stands for "Secure Copy." It is similar to SFTP. It is used to copy files from one computer to another. SCP comes installed with Linux and with Mac OS X. You can install SCP on Windows using PuTTY, and on Mac OS 9 using MacSSH.

    To use SCP, use scp <source-file> <destination-directory>. You can copy directories recursively with the -r flag.

  22. What is SSH, and how do I use it?

    SSH stands for "Secure Shell," and it is the preferred way of remotely connecting to other computers. For example, if you need to test an assignment on a Berry Patch computer, but you don't feel like physically going to the Berry Patch, you can use SSH on your personal computer to connect to and use a Berry Patch computer from anywhere on campus.

    To use SSH on the command line, type ssh <user>@<computer>, where <user> is the username you want to log in as, and <computer> is the name of the computer. If you'd like, you can leave off the user and just type ssh <computer>, and SSH will use the username you are currently logged in as. You can use the command whoami to see your username.

    You can also use SSH in a GUI environment. LTS provides GUI software for Windows and Mac OS X, while Linux has this pre-installed. If you use KDE, you can use Konqueror for GUI SSH: just go to the URL fish://username@hostname/path, replacing username, hostname, and path with there relevant attributes. If you use Gnome, you can use the Nautilus file browser for GUI SSH: Go to File→Connect to Server… and select SSH for the service type. Fill in Server with the hostname, User Name with the username, and Folder with the path.

    If you are running a GUI in X11, you can forward windows to your desktop with the -X flag: ssh -X cleo, for example.

    UNIX-like operating systems, including Linux and Mac OS X, should have SSH installed. You also can download a SSH client for Windows or Macintosh.

    For more information, enter man ssh at a UNIX terminal.

    You can also set up SSH Keys to make logging-in to pubic servers quicker.

  23. How can I get to my files in my CS account from home?

    You need to log in to one of the public workstations and copy files from there over SSH. You can use scp or sftp to copy files to your local machine. Use the hostname of the workstation you are connecting to, your CS user name, and the full path to your home directory.

  24. How can I get to files on my UNET webspace from a department Linux machine?

    You can use scp or sftp. LTS changes their shell servers from time to time. As of this writing, a list of their available shell servers can be found at http://lts.brandeis.edu/techresources/accounts/unet/serversfilestorage.html, which states that you should use conch.unet.brandeis.edu or urchin.unet.brandeis.edu for the hostname/server. Groucho (aka diane or harpo), is deprecated, and sam appears to be offline for good. For the folder use /usr/users/username, for the username use your UNET ID.

  25. Why is the machine I'm on so slow?

    You may have a process that is taking up a lot of CPU usage. To see if that's the case, type ps at the command prompt. You will see something like the following:

    	  PID TTY        TIME CMD
    	13391 pts/3  00:00:00 tcsh
    	13470 pts/3  00:00:01 emacs
    	13974 pts/3  00:00:00 ps
    

    To get rid of a process, type kill -1 PID where PID is the number in the PID column. For instance, to get rid of emacs in the above example, the user would type kill -1 13470. This should clean the process up nicely. If after a short while, ps still shows that process, type kill -9 13470.

    On Linux you can also use the graphical utility ksysguard.

  26. How do I set up my cs account to forward my mail to another e-mail account?

    Create (if necessary) the file /mnt/mail.cs.brandeis.edu/`whoami`/.forward (`whoami` evaluates to your username) by using your favorite text editor (emacs, pico, vi, etc.). The first and only line of your file should be the e-mail address you want your mail to be forwarded to.

    NOTE: This only forwards new, incoming mail that is sent to you. It does NOT transfer your existing mail from your cs account to the account you are forwarding your mail to.

    To undo this forwarding, simply remove the .forward file: rm /mnt/mail.cs.brandeis.edu/`whoami`/.forward

    See the Mail Settings page for more information.

  27. How do I read my email?

    All accounts are automatically configured to use the 'pine' and 'mutt' email clients.

    We suggest that you use pine, which is beginner friendly and easy to use. It is also a powerful mail client with many features that keep advanced users using it year after year.

    Experienced users, or those with a desire for adventure, may prefer using 'mutt', though we suggest that those who are not already familiar with mutt seek out its documentation before trying to use it.

    If you would like to configure a GUI desktop client to read your mail (such as Mozilla Thunderbird, Apple's Mail.app, or others), directions can be found below, in addition for directions on how to forward your CS email to another email account.

  28. How do I filter my email?

    See the Mail Settings page.

  29. How do I send mail with Thunderbird or Eudora or Outlook (or another third-party application)?

    We recommend not using Outlook as it has been used to propogate worms in the past.

    You can download Thunderbird for free, for Windows, Mac OS X, or Linux (though we recommend using the package manager of your distribution to install software). If you want to be able to receive your Brandeis e-mail at home, using an independent Internet Service Provider (ISP), you want to set up Thunderbird/Eudora/etc to receive your Brandeis e-mail, but send your e-mail through your ISP's account.

    Please note the following server settings for your email client:
    imap server: imap.cs.brandeis.edu*
    smtp server: contact your ISP for this info

    Also note that your email account is username@mail.cs.brandeis.edu, where username is your username.

    To send mail, your SMTP server is whatever your ISP's SMTP server is. Usually smtp.isp.com where isp.com is the name of your ISP.


    * Note: The mail server does not currently provide SSL tunneled pop/imap connections (its replacement, currently in development, will). To keep your password from traveling over the wire (or WiFi) in the clear, you may use an ssh tunnel as follows:

    ssh -L 14343:localhost:143 username@imap.cs.brandeis.edu

    If you tunnel your pop or imap connection over ssh, you should use 'localhost' for your imap server, and 14343 (or whatever other local port you select) for the port. You may also tunnel pop3 (port 110). The mail server will not accept smtp connections that appear to originate locally. To tunnel smtp from off-campus, open an ssh tunnel to a public shell server that forwards to port 25 on the mail server.

  30. How can I get a new program installed?

    Email us and tell us what program you need and why (or what for) it is useful. As a rule we have no problem installing software that someone needs for a legitimate reason.

  31. Bill Gates is promising me a trip to Disneyworld. How can I mass-forward nifty chain letters? What do I do with chain letters?

    Chain letters are bad. They're annoying, they interfere with work and take up resources that can be put to better use. (By the way, they don't actually take you to Disneyworld. They collect winners in a bus and send them off a cliff.) Also, forwarding chain letters is a violation of the Usage policy.

  32. How do I switch from ELM to Mutt without losing any of my aliases?

    The following nawk script converts the ELM aliases. Just append your .muttrc file. For more information see the Mutt homepage.

  33. How do I use emacs?

    To start emacs at the command prompt, type in 'emacs' (without quotes) and press enter.

    Emacs has a pretty good tutorial, if you open emacs and then hold down Ctrl and press \ and then type in t, ( Ctrl-\ t ) the tutorial will open.

    Alternatively, you can go here to explore an online tutorial. Or simply check out guru's quick and dirty emacs tutorial.

  34. How do I use vi?

    See the vi tutorial. Run the command 'vimtutor' (without quotes) from any shell. (Note: we are using VI iMproved, which adds some functionality to the original program, and has online help, which you may access in vi by typing ':help').

  35. How do I use the UNIX operating system (the operating system on all of the machines in the Patch)?

    The Unix help pages are a good referance. However, for beginners we recommend Oreilly's Learning the Linux OS. It's inexpensive, concise, and comprehensive.

  36. Where would I find java in the Berry Patch?

    See here for information on Java.

  37. What do I do with .pdf files?

    PDF (portable document format) files are viewable documents. You can view a .pdf file using evince on Gnome, kpdf on KDE, or Preview on Mac OS X.

    To convert a .pdf file to a PostScript file, run pdftops <input>.pdf <output>.ps

  38. What do I do with .ps files?

    PS (PostScript) files are viewable documents. If you are running Windows or MacOS, you will need to download the proper software to view these files. You will need to get AFPL or GNU Ghostscript and either MACGSView or GSView depending on your OS.

  39. How do I read newsgroups on the Macs in the Berry Patch?

    Download a Macintosh-compatible Usenet client, or configure pine to talk to the nntp server of your choice.

  40. Where do I put webpages? How can people see them?

    Put webpage files in the .www directory in your home directory. (If this directory does not yet exist, just create it: mkdir ~/.www)

    To access your home page from a web browser, go to http://www.cs.brandeis.edu/~<user>, where <user> is your CS account username.

    Note: In order for the httpd daemon to serve any files located in your web directory, it must be able to access them and read them. This does not only mean that your web directory and any content within it must be world readable, which most users realize. It also means that to permit the httpd daemon to access your .www directory, you must check the file permissions to ensure that your home directory is world traversable (though it need not be world readable). Directory traversability is set by the file executability bit. Therefore, the least destructive way to make your directory world traversable is to run chmod +x ~

    Historically, public webpages used to be served out of /web, rather than ~/.www. If you believe that you still have old data under /web that you would like to access, please contact Guru.

  41. How do I password protect my webpages to allow limited access?

    See this link.

  42. How often are the files in my home directory backed up?

    We do backups between midnight and 7 am. Any file which didn't exist overnight won't be backed up at all. We do backups once a week between Friday night and Saturday afternoon. Current policy is to keep weekly backups for at least a month, keep at least one backup a month for a semester, once backup a semester for a year, and one backup a year for a decade.

    If you accidentally delete a file which has existed for less than a week, the sooner you tell us, the better the chance that we will be able to restore the file.

    And no, there is NO way to undelete a file once you've erased it using rm.

    Alternatively, you could use command can instead of rm (you can alias rm to can by alias rm can). can puts the deleted files into a garbage can. You can list the files in the garbage can by command sniff and undelete by rummage file-name(s). NOTE: the garbage can is on local disk, that means you can only undelete the file if you're on the same machine you deleted it from.

  43. How often are my web pages backed up?

    If your web pages are stored in /web, they are not backed up. If they are stored in ~/.www they are backed up with your home directory.

  44. Where's my cgi-bin directory?

    Due to security considerations we do not allow CGI scripts on the system.

  45. It's 9 pm on a Sunday night, and I really really really need help from a guru. What do I do?

    Do a Google search to see if you can find the answer to your question elsewhere. If you can't, contact the Gurus. You can email us (preferred) at guru@cs.brandeis.edu, or call the Guru office at x6-2740. Calling the Gurus at home will only get them angry, and as such they will probably not want to help you.

  46. There's something wrong with a program/computer/printer. What do I do?

    Email Guru with as much factual information as you can find about the problem. Please be sure to include a description of the problem (both what you expect to happen, and what is in fact happening), where and when it happened, and what computer you were using (you can find a computer's name using the hostname command). The GNU Emacs manual has an excellent description of what to include in a bug report:

    When you decide that there is a bug, it is important to report it and to report it in a way which is useful. What is most useful is an exact description of what commands you type, starting with the shell command to run Emacs, until the problem happens.

    The most important principle in reporting a bug is to report facts. Hypotheses and verbal descriptions are no substitute for the detailed raw data. Reporting the facts is straightforward, but many people strain to posit explanations and report them instead of the facts. If the explanations are based on guesses about how Emacs is implemented, they will be useless; meanwhile, lacking the facts, we will have no real information about the bug.

    For example, suppose that you type C-x C-f /glorp/baz.ugh RET, visiting a file which (you know) happens to be rather large, and Emacs displayed `I feel pretty today'. The best way to report the bug is with a sentence like the preceding one, because it gives all the facts.

    A bad way would be to assume that the problem is due to the size of the file and say, "I visited a large file, and Emacs displayed `I feel pretty today'." This is what we mean by "guessing explanations." The problem is just as likely to be due to the fact that there is a `z' in the file name. If this is so, then when we got your report, we would try out the problem with some "large file," probably with no `z' in its name, and not see any problem. There is no way in the world that we could guess that we should try visiting a file with a `z' in its name.

    Alternatively, the problem might be due to the fact that the file starts with exactly 25 spaces. For this reason, you should make sure that you inform us of the exact contents of any file that is needed to reproduce the bug. What if the problem only occurs when you have typed the C-x C-a command previously? This is why we ask you to give the exact sequence of characters you typed since starting the Emacs session.

    You should not even say "visit a file" instead of C-x C-f unless you know that it makes no difference which visiting command is used. Similarly, rather than saying "if I have three characters on the line," say "after I type RET A B C RET C-p," if that is the way you entered the text.

    So please don't guess any explanations when you report a bug. If you want to actually debug the problem, and report explanations that are more than guesses, that is useful--but please include the facts as well.

    Source: GNU Emacs manual

    Please follow the standards set out in the GNU Emacs manual when submitting a bug report to Guru.

  47. How do I manage printers and print jobs?

    Point your browser to port 631 on the CUPS print server for the printer you wish to manage. For the Berry Patch printer, 'McNally', this is printing:631. For other printers, ask guru for the name of the print server. From here, you can view the status of printers, cancel jobs, and so forth. Check here if a printer is not working, or to cancel a job in the queue.

  48. I minimized a window and now I can't find it. Where did it go?

    This is a problem that appears under the Gnome desktop manager. Windows are minimized to the Gnome Pager, which has been known to vanish mysteriously. To restore it, right-click on the Gnome taskbar, and select the menu option Add Applet→Utility→Gnome Pager.

  49. I tried to start Firefox, Mozilla, or Seamonkey, but got an error message saying that it's already running, and I don't have it open. What's going on?

    The Mozilla family of browsers checks to see if another process is already using a profile by looking for the existence of a file named .parentlock in your profile. If a browser process dies or otherwise fails to exit cleanly, it can sometimes leave this lock file behind (the lock file should be present while the browser is running).

    In Linux, this file will exist at ~/.mozilla/$BROWSER/$PROFILE/.parentlock, in OSX it exists at ~/Library/Application Support/Firefox/Profiles/$PROFILE. $PROFILE usually takes the form of eight random characters followed by a '.' and the string 'default' or 'Default User'.

    On Linux you may locate this file by hand (cd; ls -Ra .mozilla | less, use '/' to enter a search query, look for .parentlock), or with the following command (NOTE: This will remove *all* instances of .parentlock in your .mozilla directory. Do not use this command without first exiting all Mozilla-family browser sessions on any machines you may be logged into.):

    cd; find .mozilla -name \.parentlock -exec rm -v {} \;

    On Mac OS X you may locate this file by hand (ls -Ra ~/Library/Application\ Support/Firefox/Profiles/ | less, use '/' to enter a search query, look for .parentlock), or with the following command (NOTE: This will remove all instances of .parentlock in your .mozilla directory. Do not use this command without first exiting all Mozilla-family browser sessions on any machines you may be logged into.):

    cd; find ~/Library/Application\ Support/Firefox/Profiles/ -name \.parentlock -exec rm -v {} \;


Didn't help? E-mail guru@cs.brandeis.edu.
Valid XHTML 1.0 Strict