doc/source/cbc_analysis.rst: added instruction for x509 proxy on gstlalcbc accounts on ICDS

doc/source/cbc_analysis.rst

@@ -71,6 +71,23 @@ For example, to grab all the relevant files for a small BNS dag:
 
 Then move the template bank, mass model, idq file, and dtdphi file into their corresponding directories.
 
+
+When running an analysis on the ICDS cluster in the gstlalcbc shared account, 
+the contents of ``env.sh`` must be changed to what is given below.
+In addition, below in the tutorial, where it says to run ``ligo-proxy-init -p``, 
+instead, run ``source env.sh`` on the modified ``env.sh``. 
+When running on non gstlalcbc shared accounts on ICDS or when running on other 
+clusters, the ``env.sh`` does not need to be modifed, and ``ligo-proxy-init -p`` 
+can be run as in the tutorial. 
+
+.. code-block:: yaml
+   export PYTHONUNBUFFERED=1
+   unset X509_USER_PROXY
+   export X509_USER_CERT=/ligo/home/ligo.org/gstlalcbc/.cert/gstlalcbc_icds_robot.key.pem
+   export X509_USER_KEY=/ligo/home/ligo.org/gstlalcbc/.cert/gstlalcbc_icds_robot.key.pem
+   export GSTLAL_FIR_WHITEN=0
+
+
 Now, we'll need to modify the configuration as needed to run the analysis. At
 the very least, setting the start/end times and the instruments to run over: