Running programs in a remote LINUX environment differs from running in windows or on a LINUX based desktop.

PRELIMINARY STEPS

The first step is opening an account, which for TAMNUN is done by completing the web form and for PHELAFEL/PHCLASSES is done by filling in the registration form , printing it and handing in to your lecturer or to Riva. You need to have an account on TX(staff)/T2 for TAMNUN and on TX/T2 or PHYSICS for PHELAFFEL/PHCLASSES before requesting an account. For the rest of these pages the name TAMNUN is used, but the course will also run on ALUF but ifAMNUN is not yet ready. Everything except the PBS link also applies to PHELAFEL/PHCLASSES. Likewise when TX (staff) is used it is also applicable to T2 and PHYSICS.

The next step is to follow thru and simply read the pages in order without taking any actions yet. Then, if you are in a course your will be given a temporary training account to use in class. If you are working thru the webpages alone, you need your account to continue. In either case it will be called YOURACCOUNT in the following. Once you have an account and have read the pages once, proceed as follows: If you are coming from a LINUX machine (like the ones in Rm 316) you can start doing as instructed below. If you are on windows you need to exercise one of the options listed on the remote access page. If you are in a TAMNUN preliminary course with your own laptop there will be people to help you at this stage or you can make an appointment with Julia at hpc@tx.technion.ac.il.

GENERAL COMMENTS

LINUX computers are case-sensitive so account and file names must be in the correct case. The filenames File.c and file.c are not the same!.

Your account, known below as ``YOURACCOUNT'' has several attributes. It has a home directory, known as ~YOURACCOUNT which is where your files sit and a shell, which defines some of the rules. A common choice is tcshell which works well if a file called .cshrc is placed in the main directory, see below.

GETTING STARTED

When you have read all the pages and decided how to access TAMNUN the next step is to open a window there to run programs.

In that window or in any window of your desktop if you are coming from a different LINUX computer you access TAMNUN with the command

ssh tamnun -X -l YOURACCOUNT

if the account name is the same you can drop the -l YOURACCOUNT.

The command ssh is a secure login and details about it are here.

The -X (or -Y) means that your TAMNUN window can open windows on your desktop.

If you come from outside the Technion firewall you will need to go into TAMNUN by first logging in to TX and then to TAMNUN.

SETTING UP YOUR ACCOUNT

First check if a file calle .cshrc is already installed in your account by writing:

ls .cshrc

If yes (i.e. if you get the file listed) go on to the list of basic commands below.

If not, a sample .cshrc file called .cshrc.TAMNUN can be downloaded here. See the editing and managing files link for how to do this and place it in the home directory. Immediately change its name to .cshrc by the command

mv .cshrc.TAMNUN .cshrc

Then run the command source .cshrc and every time after that when you logon, you will get a nice prompt like:

which helps you know which window is the right one to use. You will also have paths to your files sorted out. (The illustrative prompt here is on phelafel, since TAMNUN had not arrived when this was written; and its shows how the prompt changes when you change your directory e.g. from ~phr76ja to ~phr76ja/public_html.)

A nice list of basic commands for LINUX, prepared by Riva Kreiselman is here. Important ones are ls, mkdir, cd ....., more
more is a way to see whats in a file without opening an editor.

Now for the important stuff!

COMPILE, LINK and RUN

The environment for running jobs is different in principle to using a desktop pc. Instead of entering an environment where you write your file and then run it, you take 4 seperate stages - edit, compile and link and run (although often the compile and link are combined) after you have opened a window:

1. First you prepare one or more files in C/FORTRAN/C++ etc. You do this with an editor and this is explained in the next link. Lets start with a simple file, for example one I used in my last Computational Physics class called surlin.f. You can use it ``as is'' for this introduction. Check if it is there using the ls command and if not get it by writing:
   

   scp course01@aluf:surlin.f .
   

   and using the same password as given for your account on aluf. The period following the space at the end of the command line is a short way to say ``put the copied file in the current directory''. (If you are taking the course alone, you will need to scp it after downloading from the web onto some other computer - say one called YOURMACHINE - and then either sending it from YOURMACHINE with winscp or copying into ALUF from say YOURACCOUNT@YOURMACHINE by writing on ALUF scp YOURACCOUNT@YOURMACHINE:surlin.f . )

2. Once your file is ready, you have to compile it and then link the different parts. At this stage you create a file that will be executable, and for surlin.f the command is:
   

   f77 surlin.f -o surlin.ex
   

   where the -o means make a final executable file called surlin.ex
   and you should change this if you are compiling a different file. This is about as easy as it gets, and for more complex programs its good to work with makefiles, which are explained here. There are also many other compilers which will be discussed in detail in a more advanced setting.

    In brief, documentation about Intel compilers is at:
   
   http://aluf.technion.ac.il/doc/Intel/C.htm
   http://aluf.technion.ac.il/doc/Intel/Fortran.htm
   
   icc -V
   Intel(R) C Compiler XE for Linux, Version 12.1.1.256
   
   icpc -V
   Intel(R) C++ Compiler XE for Linux, Version 12.1.1.256
   
   ifort -V
   Intel(R) Fortran Compiler XE for Linux, Version 12.1.1.256
   
   

3. The final stage is execution which for the example file is just to write the command:
   
   surlin.ex
   

You can run the job in the background by writing

surlin.ex &

Once the job is finished, you can look at the files it has created with the ls command. For example, surlin.ex creates the file youraccount.out which you can view with the more command.

more youraccount.out

Your next page is editing and managing files in a LINUX environment.

NANCO/TAMNUN users and Technion Physics Department graduate students may contact Dr Joan Adler (phr76ja_at_tx.technion.ac.il) with further questions, OTHERS ARE WELCOME TO USE THE SITE ``AS IS''.

Course links:
1. Course homepage
2. How working on a remote LINUX machine differs from using your desktop - compile/link/run in LINUX
3. Editing and moving files in a LINUX environment
4. Accessing a remote LINUX machine from the windows environment
5. PBS queueing system - by Julia Halupovich