The -V switch gives detailed information about what TetGen is doing. Add more 'V's for increasing amount of detail.

Specifically, '-V' gives information on algorithmic progress and more detailed statistics including a roughly mesh quality report. If you've forgotten the statistics for an existing mesh, run TetGen on that mesh with the -rNEP switches to read the mesh and print the statistics without writing any files.

'-VV' gives more details on the execution of algorithms, and prints so much that TetGen runs much more slowly. While '-VVV' may be only useful for debugging.