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You can run fireworks (cmsShow) on your laptop or desktop machine and access data directly from our Tier-2 dCache.
Just put the prefix 'root://dcache-00.rcac.purdue.edu/pnfs/rcac.purdue.edu/data/' in front of the LFN.

Example:

> cmsShow root://dcache-00.rcac.purdue.edu/pnfs/rcac.purdue.edu/data/store/data/BeamCommissioning09/MinimumBias/RAW-RECO/SD_AllMinBias-Jan23Skim-v1/0014/AC5CE429-B809-DF11-85F1-0026189438A9.root

To copy a single file from the Tier-2 dCache to your local machine (laptop or desktop) you can use the command xrdcp.
First you need to initialize your ROOT or CMSSW environment (run cmsenv).

Example:

> xrdcp root://xrootd.rcac.purdue.edu//store/group/ewk/DY/DYM20/ntuple_skim_96_2_z5w.root my.root

You will get a progress bar as the file downloads. You may also want to think about using the -R option, which allows you to recursively download a directory.
Please see the details at https://silicondetector.org/display/xrd/xrdcp

If you are using ROOT, you can open files from our Tier-2 dCache just like you would any other file:

TFile::Open("root://dcache-00.rcac.purdue.edu/pnfs/rcac.purdue.edu/data/store/data/BeamCommissioning09/MinimumBias/RAW-RECO/SD_AllMinBias-Jan23Skim-v1/0014/AC5CE429-B809-DF11-85F1-0026189438A9.root");

This returns a TFile object, and you can proceed normally.

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