freq2gnuplot.rb has been obsolete.
freq2gnuplot.rb reads BAND and print gnuplot style data text to
standard output (STDOUT). The number of phonon modes must be
freq2gnuplot.rb [BAND] N
N = the number of phonon modes
Unit conversion factor. VASP users may use 15.633 in THz or
521.47 in cm.
default = 1.0