CINT Launch Issue with root

I am following the C++/ROOT exercise used to prep for the CMS Open Data workshop and am running into an issue when I try to launch CINT.

Tutorial Link: Using ROOT with C++ to fill a histogram – C++ and ROOT

This step is after the make histogram section. As shown in the tutorial I enter “root -l output.root” into the command prompt and get the following error:

/opt/cms/slc6_amd64_gcc472/cms/cmssw/CMSSW_5_3_32/external/slc6_amd64_gcc472/bin/root: can’t figure out DISPLAY, set it manually
In case you run a remote ssh session, restart your ssh session with:
=========> ssh -Y

I tried re-starting the container and docker as recommended by a few Google searches with no luck. Does anyone know how to resolve this issue? Thanks!