[[asc:workbook| <<back]]

====== Getting Started with Athena ======



Set up your for ATLAS software according to [[asc:workbook_introduction |Setting Up Account]]. Because we are running from a Kit rather than at CERN, you do not need a cmthome directory. It's advised not to create one, in fact.

Checking out Athena and Running Athena !HelloWorld*
  * Set up the Athena environment as above.
  * Get a kerberos ticket by typing:

<code>/usr/kerberos/bin/kinit username@CERN.CH</code> 

Note: CERN.CH is case sensitive. You will need a lxplus account for "username" is your lxplus account. (if you're having problems, try _kinit -4 username@CERN.CH_)


If your name at CERN different, you should create a file  "config" inside  ".ssh" directory and add:

<code>
  Host svn.cern.ch
  User USER_NAME_AT_CERN
  GSSAPIAuthentication yes
  GSSAPIDelegateCredentials yes
  Protocol 2
  ForwardX11 no
</code>

(replace USER_NAME_AT_CERN by your actual user name at CERN). Create, and go to your test area, e.g. ~/testarea/RELEASE (e.g. 14.5.1) 
 <code>cmt show versions PhysicsAnalysis/AnalysisCommon/UserAnalysis</code>
will return a string containing a "tag collector" number which will look like _UserAnalysis-nn-nn-nn_. (For 14.2.20, it is UserAnalysis-00-13-06)
Issue the command 

<code> cmt co -r UserAnalysis-nn-nn-nn PhysicsAnalysis/AnalysisCommon/UserAnalysis</code>
This can take a minute or two to complete. Go to the CMT directory of the newly-checked out package by issuing the command

<code>cd PhysicsAnalysis/AnalysisCommon/UserAnalysis/cmt</code> 

Setup the package by issuing the command:

<code>source setup.sh</code> 

Go to the run directory  "cd ../run"
Execute the following command to get the runtime files

<code> get_files -jo HelloWorldOptions.py</code>

Run athena: issue the command:

<code>athena.py HelloWorldOptions.py</code>

The algorithm will first initialize and will then run ten times (during each run it will print various messages and echo the values given in the job options file). Then it will finalize, and stop. You should see something that includes this:

<code>HelloWorld INFO initialize()
HelloWorld INFO MyInt = 42
HelloWorld INFO MyBool = 1
HelloWorld INFO MyDouble = 3.14159
HelloWorld INFO MyStringVec[0] = Welcome
HelloWorld INFO MyStringVec[1] = to
HelloWorld INFO MyStringVec[2] = Athena
HelloWorld INFO MyStringVec[3] = Framework
HelloWorld INFO MyStringVec[4] = Tutorial</code>

...If so you have successfully run Athena !HelloWorld.

====== Running AnalysisSkeleton on an AOD file ======


This is basically same as the instructions in the ATLAS twiki page [[https://twiki.cern.ch/twiki/bin/view/Atlas/WorkBookReadingAOD|here]].
   
<code> AnalysisSkeleton.DoTrigger = False</code> 

    * You don't have to do this for 14.5.1 or later. The switch is set to false by default. 
  *   The AOD data file must be compatible with the Athena version you are using. For workshops and Jamborees, a list of compatible and available files will be provided in the workshop specific wiki.


Using external database from BNL:

<code>
## EXTERNAL DB 
from AthenaCommon.GlobalFlags import GlobalFlags 
GlobalFlags.DetGeo.set_atlas() GlobalFlags.DataSource.set_data() 
from IOVDbSvc.CondDB import conddb</code>
 --- //[[chekanov@gmail.com|Sergei Chekanov]] 2011/03/09 17:16//