1. CALES 1(Unix/Linux) FAQ



1.1 How to apply for an account?


"UNIX Account Application Form" is available at here.


  • Account will be issued to you through email within 3 working days after submit to us. Ensure your email address was clearly stated.
  • If you already have an account, do NOT apply the second time. Even if you have forgotten your password, the system administrator or the person-in-charge can always let you change your password. If you can not remember whether you have an account, please check it out with the person-in-charge. Do not submit two copies of the application form. If you are not sure whether the first copy of your application form have already been received and account created, please check with the person-in-charge instead of submitting another form.
  • Do not delete or edit the environment files that have been created in your account. If you are unable to use any software, please check that you have the environment files (.cshrc & .login) in your HOME directory and that the content are correct.
    The environment files are: .cshrc and .login

content of .cshrc

source /usr/local/Cshrc

content of .login

source /usr/local/Login

If the files are missing or the contents are different, please create/change them, save the files, logout and then login again for the setting to be effective.


1.2 How to change my login password?


The command to change password is "yppasswd". Just run the command "yppasswd" and the system will prompt you for the old password and then let you input the new password. You need to re-enter the same new password for it to take effect.

Please note that you will NOT be able to modify your password if the System Administrator is updating the password file for task like creating new account ... etc. Therefore, try changing your password again in the later time.


1.3 How to check my disk quota and apply for quota increase?


To check your disk quota, you may either open a terminal or run the command:  quota -v [test@lxa1 ~]$ quota -v
Disk quotas for user test (uid 99999): Filesystem                 blocks    quota    limit    grace     files   quota   limit   grace
svr:/xxx/test             78800    99000  105000              360       0        0

From above example, the user test is granted disk quota of 99MB while 78.8MB has been used already. To request for more disk space, please fill in the "Disk Quota Request Form", available at below web page: http://www.eng.nus.edu.sg/eitu/unix/quota_app2007.pdf

Please be reminded that:

  **** Always keep your directory neat.
  **** Delete core file, log file, .mozilla and software generated temporary files. Ensure your Trash was empty after file deleted.
  **** Limit is shown in the fourth column when you type "quota -v". Users can exceed their quota (third column) but not the limit (fourth column). After exceeding the quota, user have 1 week time allowance to keep their directory within the quota. This means that users can have a temporary big disk space of 1 week to allow them to run their job. But they can not keep their data permanently above their quota. Default quota/limit for staff and undergrad student is 50/55MB, post-grad is 99/105MB.

Those users running big job (e.g. Abaqus & Cadence) are suggested to run the simulation at public temporary folder "/var/tmp". Please copy the source file (user's design file) and the simulation results to your HOME directory as the public folder will be cleared by system regularly.

The main objective of CALES 1 is to satisfy the basic need of all users: undergrads, postgrads and staffs of Faculty of Engineering (about 1700 users). Due to the limited disk space, do NOT ask for more quota to store multiple sets of results, games and public domain softwares that are not related to your project. DO NOT keep unnecessary big files like core, object file (*.o files), log file and software created intermediate temporary file in your directory. The question of how much quota each person should have is a tough one. Every person has different needs. Every application software has different needs as well. As CALES 1 is a share resource among so many people, the System Administrator task is to ensure everyone can execute their program and be able to run the application software required for their project. Users are strongly discouraged from storaging big files or multiple sets of results in their directory.


1.4 How to logout Linux Workstation?

For workstations running on RHEL 5.0 in clusters WS1&WS2:
Left click on the ‘System’ icon which is shown at the left upper line of desktop. Select ‘Log out’ to logout. For workstations running on RHEL 4.0 in clusters WS3&WS4:
Left click on the ‘Actions’ icon which is shown at the left upper line of desktop. Select ‘Log out’ to logout.

It is a good habit to close all the windows you have opened before you logout. Also remember to check your quota usage everytime before you logout. Make sure that your disk usage is less than the quota. Otherwise you will encounter problem when login next time.


1.5 How to access CALES 1 after office hour?


All UNIX account holders with NUS staff/matric card and pin number are granted access to CALES 1.

Unrestricted hours entry: Door is unlocked; no card is required
   Monday to Friday: 8:00am to 6:00pm
   Door is unlocked; no card is required

Restricted hour’s entry: Door is locked; card is required with pin-number (6 digits)
   Monday to Friday: 6:00pm to 12:00am
   Saturday:8:00am to 6:00pm

Locked entry: Door is locked; no access is allowed
   Monday to Friday: 12:00am to 8:00am
   Saturday:12:00am to 8:00am; 6:00pm to 12:00am
   Sunday & Holiday: whole day

For card access error or permission denied problem, or other access card related matters, please report the problem by filling in the form at the CALES 1- Help Desk, E1-04-01.


1.6 How to print file from workstations?


Printers available in CALES 1 are:

      HP LaserJet 4000  (located at WS3, E1-04-12)
      HP LaserJet 9000  (located at WS4, E1-04-11)

Please use appropriate application to open & print the file.



1.7 How to open a Text Editor for Linux Workstation?


For text editor, please run command:   gedit For MS-Word .doc format compatible editor, you may use OpenOffice.org writer.


Click on the ‘OpenOffice.org Writer’ icon which is shown at the upper line of the desktop.
Left click on the ‘Applications’ icon which is shown at the leftmost upper line of screen. Select ‘Office’ followed by the ‘OpenOffice.org Writer Word Processor’.



1.8 What are the useful Linux commands?


Here are some useful Linux commands:
1) pwd               - show current directory
2) ls                  - list files in directory
3) cd                 - change directory
4) more             - view file page by page
5) cp                 - copy file
6) rm                - delete file
7) mv               - move/rename file
8) scp               - transfer file

More Linux commands can also be found in /bin directory. For detailed description of each command, please run the Linux Online Manual command "man".

For example:
"man ls"           - display manual for "ls" command
"man cd"          - display manual for "cd" command

For whatever commands you found in the /bin directory, if you want to find out the detail of that command, please run "man ".



1.9 How to backup my files/data ?


There are several ways to backup your files/data.

  • Use USB thumb drive
    After plug-in the USB thumb drive, an icon of that USB will pop-up on the desktop. Click that icon, a window will open displaying the content stored in the USB. Then you may drag & drop to do the backup.
    Note: To safely remove the USB thumb drive, please close all windows which are USB related, and then right click the USB icon on the desktop and select 'unmount volume' before un-plug the USB.

  • Backup via email attachment
    Go to NUS homepage, click 'myEMAIL' on the upper-right corner.

  • Backup via NUS H Drive
    NUS HDrive is a personal network drive where you can store your files online.
    Open a web browser, go to http://www.nus.edu.sg/comcen/hdrive , and login in using your NUS username and password. You will be able to upload and download files from your H Drive. Each user gets an H Drive with a size limit of 4GB.

  • For backup to PC (Microsoft Windows), there are some free tools, such as WinSCP, FileZilla Client etc. which can be downloaded and installed on your PC. They are easy-to-configure and easy-to-use tools.

    For backup to Linux machine, use command “scp” which is a very useful tool for secure remote copy.
  The “scp” command syntax to send file or directory to a remote computer:
    scp -r /path/filename username@remotehost:/path
  The “scp” command syntax to retrieve file or directory from a remote computer:
    scp -r  username@remotehost:/path/filename  .
  Here are the meanings of “scp” command options:
  • -r = recursively copy entire directory
  • . = current directory
  •   '/path/filename' is the complete directory path and name where the file resides. 'username@remotehost' is the target/destination computer name. You need to provide your login name ‘username’ and will be asked for user password.
    Dot (.) at the end of the command means the files will be copied to the current directory. Of course you can change the destination to any directory you wish, just type the full path and directory name to replace the dot(.).
      E.g. copy file ‘myfile’ to lxa1.cadcam.nus.edu.sg under /var/tmp, type 
          scp  myfile  lxa1.cadcam.nus.edu.sg:/var/tmp
        copy directory ‘myproject’ from lxa1 /var/tmp to lxa2 /tmp, type
          scp  –r  lxa1:/var/tmp/myproject  lxa2:/tmp
        (no need to specify the workstation’s full name if copy between CALES1 workstations)
      You can find more details in the “scp” manual page by invoking “man scp” from Linux command line terminal, if you could at least read it once to get a better understand of the command.



    1.10 How to login remotely with graphics running to UNIX workstation?


    If your machine is running on UNIX/Linux, you need to type command “ssh –X username@remotehost”
    Note: X is in uppercase. ‘username’ is your UNIX A/C login name. ‘remotehost’ is the cluster workstation name, such as ‘lxa1.cadcam.nus.edu.sg’.
    If your machine is running on Microsoft Windows, you need to have X-Win32 installed.
    10a) For the latest X-Win32 Version 8, pls click here:
    10b) For the previous X-Win32 Version:
    Both X-Win32 and ssh client need to be installed on your PC to enable remote graphical running.

    For X-Win32 installation: In X-Config, make sure select ‘Multiple' under ‘Window' tab.
    For ssh client installation: To use ssh client you must download Putty.exe from Internet. PuTTY.exe is a program that makes Windows users establish a secure connection to Unix (and Linux) terminals. Putty.exe can be searched and free downloaded from Internet. Double click the downloaded file putty.exe. Follow the below instruction to set login session.

    Steps for launching remote graphically running:

    1. If you are connecting from outside NUS network, you will have to install computer centre's VPN and login through VPN to access CALES 1 workstations.
    2. Launch X-Win32 first. There will be an icon of X-Win32 displayed at the right bottom corner on your screen.
    3. Launch Putty and login to the session you have set.
    4. After the session, remember logging out by typing ‘exit’.

    1.11 What are the softwares installed in CALES 1 Clusters?


    Click here

    1.12 What is the IP Address of the UNIX workstation?
    IP Address
    Host Name



    1.13 How to seek help if you encounter problem in CALES 1?


    Immediate help provided from CALES 1 helpdesk.
    Contact of CALES 1 support staff
    Staff in charge on UNIX account, UNIX quota and Card access,
    Name :Ms Susan Ong
    Email : engongss@nus.edu.sg
    Tel : 65162491.

    Staff in charge on Software Installation & Licensing or any software matter,
    Name : Ms Wang Ying
    Email : engwy@ nus.edu.sg
    Tel : 65167223

    Alternative, you may report the problem by filling in the form at the CALES 1- Help Desk, E1-04-01.