diff --git a/src/read_write.c b/src/read_write.c
--- a/src/read_write.c
+++ b/src/read_write.c
printf (" Usage: uvs_stellar_spectrum [options]\n\n");
printf (" options are:\n");
printf (" [-g] Generates the default parameter file \n");
+ printf (" [-p] <parameter_file> : Use inputs from <parameter_file>\n");
printf (" [-h] help \n\n" );
printf (" In the absence of command line options, the program would\n");
printf (" read inputs on stellar magnitude, reddening and spectral \n");