The RNPL compiler is called from the command line with the following command:
rnpl -lang [program_file]
The switch -lang tells RNPL what the target output language is, c, f77, or f90.
The compiler generates code for two programs, the solver and the initial data generator. If program_file is specified, rnpl will output the solver code to a file. The extensions .rnpl or _rnpl will be removed from the end of program_file if they exist. The appropriate extension for the output language is then appended (.c or .f). The initial data generator is written to program_file_init plus the appropriate extension (.c or .f) If no program_file is specified, rnpl reads from stdin and writes to stdout. In this case, the initial data generator goes to r_out_init (.c or .f). Errors are directed to stderr.
RNPL sends the code for the update routines to a file named updates(.h or .f). Also, a default attribute file is produced, named .rnpl.attributes.
In the case of FORTRAN output, two include files named globals.inc and other_glbs.inc are also produced.
The compiler needs certain support files which it looks for in the current directory or in the directory defined by the environment variable RNPL_PATH.