Before you use CRAB for the first time, you have to configure the BOSS tools and then log out:

• source /code/osgcode/cmslocal/crab/CRAB/crab.sh
• /code/osgcode/cmslocal/crab/CRAB/configureBoss
• exit

After logging back in:

1. Set up the ORCA environment and go to your ORCA area where your job code is and do:
   
   1. eval `scram runtime -sh`
   1. voms-proxy-init -valid 120:00 --voms cms:/cms/uscms/Role=cmsuser
2. source /code/osgcode/cmslocal/crab/CRAB/crab.sh
3. Create a CRAB configuration file, crab.cfg, such as this one which successfully submits a job to the T2 at Nebraska:

[CRAB]
jobtype = orca_common
scheduler = condor_g
[ORCA]

dataset = jm03b_Zjets_20_50
owner = jm_2x1033PU761_TkMu_2_g133_OSC
data_tier = Digi,Hit
executable = ExDigiStatistics?
output_file = digistatistics.aida
orcarc_file = orca_orcarc.main
[USER]
total_number_of_events = 10
job_number_of_events = 10
return_data = 1
use_central_bossDB = 0
use_boss_rt = 1
[EDG]
lcg_version = 2
max_wall_clock_time = 1300
CE_white_list = unl
virtual_organization = cms
retry_count = 0
lcg_catalog_type = lfc
lfc_host = lfc-cms-test.cern.ch
lfc_home = /grid/cms

1. create and submit the crab jobs:

crab.py -create -submit

You can details of job monitoring, output retrieval, handling etc. from the developers quite clear documentation in:

http://home.fnal.gov/~gutsche/computing/crab/crab.html

Important commands are:

• To check the status of a job: crab -status -continue crab_?_date_time
• To retrieve job output: crab -getoutput -continue crab_?_date_time

where crab_?_date_time has the same name as the directory created for your crab jobs, i.e. crab_0_060412_105902.