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.
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.
M_CLI2 use a command prototype to define and read command-line arguments including support of response files for abbreviating command calls with many options
M_CLI use a command prototype to define and read command-line arguments and leverages NAMELIST so no type conversion from strings is required
f90getopt 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.
kracken is an open-source library for parsing Unix-like command-line arguments. It is now provided in Github in the General-Purpose-Fortran library (GPF) with a lot more functions than CLI option parsing. It is also available on github as an fpm(1) package M_kracken, as well as an older stand-alone version at M_kracken95.
CLAF90 is a f90-module for parsing command line arguments. Note the original location is no longer accessible.
fargParse, part of the Goddard-Fortran-Ecosystem
paramcard command-line parameter input made simple, by Takahiro Ueda
command_args from arjenmarkus
FTN_Getopt by Reinhold Bader
libsim libraries from ARPA-SIMC include a general purpose library with many modules including parsing command-line arguments.
get_namelist shows using NAMELIST groups to crack the command line
argv-fortran a better GET_COMMAND_ARGUMENT() for Fortran that returns the argument in an allocatable character string, by Jacob Williams
f2kcli is an implementation of the Fortran 2003 command line interface for compilers which do not support Fortran 2003.
Fortran code on github is a general list of Fortran code that includes packages with command-line parsers.
Wrappers around C libraries are an alternative approach. Some example candidates …