From the Login Node
Just like LXPLUS CERN machines (CERN Public Login Linux system) , the CMS Connect login node machine (login.uscms.org) environment has access to CVMFS (CERN-VM File System), which holds the CMS Software Releases. The default unix shell in the system is BASH. If you are not familiar with using Linux, see this list of basic Linux Commands.
Here is an example of how to access a certain release of the framework via CVMFS:
Please, refer to this Twiki link for a list of all CMSSW Releases available via CVMFS.
From the Worker Nodes
It is important to nice that the User Home Area and Environment is not inherited from the login node machine to each worker node (the actual machines where jobs will run). Tier-2 and Tier-3 resources do have access to CVMFS though. So, while submitting a job that requires the CMSSW framework, you will need to source the CMS source script first.
Here is an example of how to setup your CMSSW framework on your job environment, considering your worker node has CVMFS access:
Creating and unpacking a Sandbox
If you need to add packages to your local CMSSW and don’t want every worker node to pull data and build every time, you can create a sandbox and unpack it on the worker node.
To create the sandbox, simply pack it with tar
To use it, you might want to create a new release though, to be sure CMSSW_BASE and other variables are not hardcoded in the configuration setting paths. Here is an example: