View source for Tutorial — Basic usage of CC-IN2P3

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== Tutorial — Basic usage of CC-IN2P3 ==

=== Introduction ===

This tutorial is part of a collaborative wiki: feel free to update it, modify it, or add relevant information for future users.

=== Connecting to the computing center ===

From a local terminal on your computer, you can connect to the CC-IN2P3 server using SSH:

<pre>
ssh <USERNAME>@cca.in2p3.fr
</pre>

After entering your username and password, if the connection is successful you should see a message similar to:

<pre>
################################################################################
               _________________________________________________
              |                                                 |
              | Bienvenue au Centre de Calcul de l'IN2P3 / CNRS |
              |_________________________________________________|

Pour votre utilisation quotidienne des serveurs interactifs,
merci de consulter le guide des bonnes pratiques :
https://doc.cc.in2p3.fr/fr/Daily-usage/access/cca-connect.html#cca-best-practices

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                ______________________________________________
               |                                              |
               | Welcome to the IN2P3 Computing Center / CNRS |
               |______________________________________________|

For your daily use of interactive servers, please read the best practices guide:
https://doc.cc.in2p3.fr/en/Daily-usage/access/cca-connect.html#cca-best-practices

################################################################################
</pre>

You now have access to a terminal on the computing center in Lyon.

=== Preparing a job ===

Create a new directory and move into it:

<pre>
mkdir test_hello_world
cd test_hello_world
</pre>

Copy an example C program:

<pre>
cp /pbs/throng/l2it/tutoriel_exemple_file/hello_world_c/hello_world.c ./
</pre>

You can inspect the file with:

<pre>
cat hello_world.c
</pre>

Compile the code to create an executable:

<pre>
gcc hello_world.c -o hello_world
</pre>

=== Submitting a job ===

Copy a job script:

<pre>
cp /pbs/throng/l2it/tutoriel_exemple_file/hello_world_c/job.sh ./
</pre>

Inspect it with:

<pre>
cat job.sh
</pre>

Lines starting with #SBATCH provide instructions to the scheduler (job name, time limit, memory, etc.).  
The command:

<pre>
./hello_world > hello_world.out
</pre>

runs the program and saves the output.

Submit the job:

<pre>
sbatch job.sh
</pre>

You should see output similar to:

<pre>
Submitted batch job XXXXXXXX
</pre>

Check the job status:

<pre>
squeue
</pre>

If the job no longer appears, it has completed.

View output files:

<pre>
cat test_XXXX.log
cat hello_world.out
</pre>

Expected result:

<pre>
Hello, World!
</pre>

=== Cancelling a job ===

To cancel a job:

<pre>
scancel <JOB_ID>
</pre>

Find the job ID with:

<pre>
squeue
</pre>

=== Downloading data locally ===

To copy files from the computing center to your local machine:

1. Exit the remote session:
<pre>
exit
</pre>

2. Use scp from your local terminal:

<pre>
scp <USERNAME>@cca.in2p3.fr:test_hello_world/hello_world.out ./
</pre>

The file will be copied to your current directory.

=== Further resources ===

* https://doc.cc.in2p3.fr/index.html