To call gnatprep use:
$ gnatprep [`switches`] `infile` `outfile` [`deffile`]
is an optional sequence of switches as described in the next section.
is the full name of the input file, which is an Ada source file containing preprocessor directives.
is the full name of the output file, which is an Ada source in standard Ada form. When used with GNAT, this file name will normally have an ads or adb suffix.
is the full name of a text file containing definitions of preprocessing symbols to be referenced by the preprocessor. This argument is optional, and can be replaced by the use of the `-D' switch.