Parsing command line arguments with NAMELIST Try running ./parseargs ./parseargs i=4 j=5 ./parseargs j=4 i=5 Prior Work http://agentzlerich.blogspot.co.uk/2010/06/how-to-parse-fortran-command-line.html http://www.urbanjost.altervista.org/LIBRARY/libCLI/arguments/namelist/index.html