If specified abundances of informative messages are output to stderr. To make use of this information, you may want to write the standard uvspec output to one file and the diagnostic messages to another. To do so, try (./uvspec < uvspec.inp > uvspec.out) >& verbose.txt (depending on your shell you might need a slightly different syntax). The irradiances and radiances will be written to uvspec.out while all diagnostic messages go into verbose.txt. See also quiet.