To generate a fresh VOMS proxy :

$ source /cvmfs/oasis.opensciencegrid.org/osg-software/osg-wn-client/3.6/current/el8-x86_64/setup.sh
$ voms-proxy-init -rfc -voms cms -valid 192:00

 

To check the validity of an existing proxy:

$ voms-proxy-info