At IIHE

Login to a machine and define the CMS environment variables

• login to the lxpub2 or lxpub3 machine

 e.g: ssh -X username@lxpub2.iihe.ac.be

• source the CMS environment

 setenv VO_CMS_SW_DIR /msa3/cmssoft
 source $VO_CMS_SW_DIR/cmsset_default.csh ## initialize the cms env

• define the code cvs repository

 alias cmscvsroot 'source $CMS_PATH/utils/cmscvsroot.csh'
 cmscvsroot CMSSW

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Prepare the CMSSW working area

Follow these steps:

• install a CMSSW working area, go to the src subdirectory and prepare to compile and run

 scramv1 p CMSSW CMSSW_1_0_1; cd CMSSW_1_0_1/src; eval scramv1 runtime -csh

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Get the necessary code and compile it

• log onto the cvs code server; type 98passwd as password

 cvs login
 CVS password: 

• checkout the source code of the libraries that you want to use or modify. Here we will use the interface to the Pythia event generator

 cvs co -r CMSSW_1_0_1 IOMC/GeneratorInterface/test; cd IOMC/GeneratorInterface/test

• compile the code

 scramv1 b

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Run CMSSW interactively and produce a few events

The parameters for CMSSW are specified in a text file called the config file. This file can include other config files using the #include directive. Let's run the standard example which produces Higgs events decaying into 4 muons in the final state, and plots a few distributions:

 cmsRun pythiaHZZ4mu+analysis.cfg

You should see two root files appear: one with the generated events stored in HepMC format, and one with the distribution histograms. Did it work ? In case of problems, do not hesitate to contact Jan Heyninck or Pascal Vanlaer.

At this stage you should learn more about CMSSW by studying the CMSSW Workbook, chapters 2 to 4.

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