macro control of output
To run, add
/vetotank/output path/to/myoutput
in macro before beamOn, and perform
vetotank <macro>
vetotank will write at path/to/myoutput.root

The old way of run is reserved. It is to run
vetotank <macro> outputfile
at vetotank/, and the programe will write at vetotank/outputfile.root
and mv it to vetotank/output/ after the run done.