Computer Science Network Information

The Computer Science Network (csn) is composed of machines running Solaris, Linux, and Windows operating systems.  This document will provide basic information about the CSN UNIX machines, such as machine names, resources available, various methods to gain access to those resources and some basic commands.   Please feel free to contact us at csnhelp@cs.ou.edu or call 405-325-4042 if you have any problems or questions.

Accessing the CSN

The first thing needed to access the CSN is a CSN computer account.  This is only needed if you will be accessing one of the UNIX machines on the CS network.  If you will be logging in to a Windows computer on our network then your account is created and maintained by ECS.  Questions and help with your ECS account can be obtained by calling 325-4409 or emailing needhelp@ou.edu.

In most cases your CSN account will be auto-generated for each class that will require assignments be completed using the UNIX environment.  Please check with the TA for your class to see if it has been auto-generated.  If that is not the case then an individual account can be applied for the CS website at www.cs.ou.edu/students.  For auto-generated accounts the username and password will be communicated to you by your instructor or the TA.  Individual account information must be picked up from the receptionist at the Computer Science offices.

IMPORTANT ACCOUNT INFORMATION

·           Accounts expire within two weeks after the end of each semester.

·           Home directories will be purged after the accounts have expired.

·           50 page per month print quota.  Reset at the first of each month.

Armed with your CSN account you are ready to access one of the UNIX systems.  Your instructor or TA may want you to use certain machines, if so those hostnames will be given to you in the assignments.  Please consult the following table for to determine which host you need to log in to:

Please refer to the CsnResources.html document for a list of hosts.

All of the machines are in the cs.ou.edu domain, and should be accessible by their hostname if you are located within the ou.edu domain.  If you are outside of the ou.edu domain you must reference the fully qualified internet domain name,

EXAMPLE:   ssh gpel3.cs.ou.edu

Sftp is the only allowed ftp program allowed to move files to machines in the CSN.  You can connect to machines from the CSN with ftp.  Both ssh and sftp requirements are enforced to keep usernames and passwords encrypted and safe from network sniffers.

Machines with XDMCP allow you to use windows software such as XWin32 or Exceed to establish an X windows sessions and run X applications remotely.

Machines with EL158 indicated are located in the CS lab located in the Engineering Laboratory building (a.k.a. EL) in room 158.  Room 158 is located at the east end of the building.  You can sit down and log in directly from the console on these machines.  When logging in to these machines it is recommended that you select CDE for your window manager.  It is a little more user friendly and supported.  Gnome is also available on these machines but may require a little modification to your startup files before it will work on the Solaris machines.  Roam3 is a Linux machine and only has gnome and KDE available.

UNIX Environments (shells)

The popular UNIX shells (bash, tcsh, sh, csh) are available on our network.  All auto-generated accounts will be set up to use the bash environment.  Some common interactions with your shell are:  adding or changing environment variables, using tab completion, command history, each described below:

Environment Variable Maintenance

Add or changing variable to your environment:

bash:  export <VARNAME> = <VALUE>

tcsh:  setenv <VARNAME> <VALUE>

EXAMPLE:   To add the value /home/ralf1345/bin to my system PATH

bash: export PATH =  /home/ralf1345/bin:$PATH

tcsh:  setenv PATH =  /home/ralf1345/bin:$PATH

Tab Completion

Both shells allow for tab completion.  Tab completion is pressing the tab key while typing a command and the shell will automatically complete what it can match up to a point of difference.

EXAMPLE:   I have three files named:  myinput.data, run1output.data, run2output.data.  I want to print the files at some point and type the following:

lp my<TAB>

When I press the tab key the shell fills in with the rest of the filename for myinput.data.  Then I can simply press <Enter> and the command executes.  Now I want to print the run2output.data file and I type: 

lp ru<TAB>

Now the shell fills in up to the "n", since it doesn't know whether to choose 1 or 2.  At this point pressing TAB twice rapidly will list the near matches.  At that point I enter a 2 and then <TAB> again and the rest is completed.

Command History

Using the up and down arrow keys you can scroll back and forth through previously entered commands.  They are editable.  This can save a lot of keystrokes and help you remember previous commands from previous log in sessions.

Important Environment Variables

PATH - The PATH variable is a list of directories that the shell / OS will search through for the given command.  The default PATH is adequate in most cases.  Certain classes may require that you update your path to point to special programs.

LD_LIBRARY_PATH - When you are compiling programs that you have written or modified, and you need to compile them, you may encounter errors stating that certain libraries could not be found.  The default LD_LIBRARY_PATH is adequate in most cases, but may need to point to additional directories containing the libraries you need.

Help

Help on UNIX commands and programs are available from many sources.  The most common is the man page system.  To access help for a command from the man page system simply enter:  man <command>

This will display the syntax and useful information for the command in question.  A second form of help is through the info system.  This is presented in more of a manual format.  Not all UNIX commands have info formatted files, but info will return a manpage for the command/program in question.  The Computer Science website www.cs.ou.edu/students has many helpful links.   You can download the latest version of the ssh client for windows from here.  Also using google (www.google.com) you can find a wealth of information on practically any UNIX topic you may be interested in.

Common Commands

ssh - Use to establish a secure encrypted connection to a remote computer:

            ssh <username>@<hostname> 

sftp - Secure replacement for ftp.

            sftp <username@<hostname>

cd - Change Directory. 

            cd ~    - Will change your present working to your home directory.

            cd <pathname> - to change the present working directory to <pathname>.

pwd - Print the present working directory.  This is a good idea before removing or copying files.

            pwd  - Will simply print the present working directory to stdout.

cp - Copy files.

            cp <filename1>  <filename2>

mv - Move a file from one location to another.  Useful for renaming files.

            mv <filename1> <filename2>

lp or lpr - Use to print a file.

            lp filename

            lpr filename

UNIX File Editor programs

The CSN has the following file editors installed:

vi, pico, gvim, emacs

Each editor accomplishes the same tasks.  It is purely a personal preference on your editor of choice.  There are many websites dedicated to the different editors.  Man pages or info manuals are available.

Compilers

The CSN has the following compilers installed and available:

gcc, g++, and g77

The TA for each class will instruct you on the use or requirements for your assignments.  Man pages, Info, and google are excellent resources for resolving questions related to compiling problems.  Remember the LD_LIBRARY_PATH variable.  It can solve many problems.

Tech Support

Please email questions to csnhelp@cs.ou.edu, and you should get a response within 24 hours or stop by our offices in the Engineering Lab room 113 or call 325-4042.

Backing Up Your Data

As mentioned earlier your auto-generated classroom account will expire between semester and your home directory will be purged.  If you would like to save a copy of your files then you may want to use the following suggestions:

·           create a backup file containing all of your home directory with the tar command:

            tar cvf /tmp/csfall2002.<username>.tar  /home/<username>

·           Now compress the file: gzip /tmp/csfall2002.<username>.tar

·           Then sftp it to an offsite location: sftp <username>@lincoln.ecs.ou.edu

·           And finally delete your tar file:  rm /tmp/csfall2002.<username>.tar.gz