I am a newcomer to MinGW and I have a very simple question. I installed MinGW and ran simple FORTRAN programs using the gfortran compiler.  I have to write and run programs that read many input data files and/or produce many output files. I am wondering if there is a way, other than specifying the filenames in OPEN statements, to  establish a correspondence between the unit numbers and the filenames.  In Unix, it is possible to write scripts with SETENV statements associating filenames to unit numbers.  The FORTRAN program makes use of the GETENV procedure to obtain the names..  I am wondering if something similar exists for gfortran on a Windows system.  If not, what is the best way to provide the filenames to the program without a recompilation each time the filenames are changed ?