Fortran 95 and earlier had no standard support for obtaining command-line arguments. However, with Fortran 2003, several new standard procedures were added to help parse command-line arguments: get_command_argument, get_command, and command_argument_count.
krackenis an open-source library for parsing Unix-like command-line arguments. It is now provide in Github as an General-Purpose-Fortran library (GPF) with a lot more functions than CLI option parsing.
M_CLI use a command prototype to define and read command-line arguments
f2kcli is an implementation of the Fortran 2003 command line interface for compilers which do not support Fortran 2003.
getopt.f90 by Mark Gates is no longer available under http://ews.uiuc.edu/~mrgates2/research/getopt.f90. But Hani Andreas Ibrahim forked the module and provides an extended version in GitHub. It parses GNU- and POSIX-style CLI-options with and without arguments. Just one module and can be learned in minutes. Wiki, sample program provided.
~CLAF90 is a f90-module for parsing command line arguments.~ Not available anymore.
FLAP a Fortran command Line Arguments Parser for poor people. A KISS pure Fortran Library for building powerful, easy-to-use, elegant command line interfaces.