Info sources for Programming

[Cliff Rice <cliff@neosoft.com>]

I'm fairly new to the Linux scene and have found a nifty program
on the net I'd like to build called "GRASS".  I'm running potato
with a kernel of 2.2.12 and have what I think is all of the
programming libraries and such.  However when I did a build on
GRASS 4.3 , I got the following at link time. I have programmed
GIS programs before and would like to start using this one.

OBJ.i386/main.o: In function `main':
OBJ.i386/main.o(.text+0x246): undefined reference to `clear_input'
OBJ.i386/gis_pars.o: In function `yyparse':
OBJ.i386/gis_pars.o(.text+0x1cd): undefined reference to `yylex'
collect2: ld returned 1 exit status
make[1]: *** [/mnt/grass4.3/i386/etc/r.combine] Error 1
make[1]: Leaving directory `/mnt/grass4.3/src/raster/r.combine/cmd'
make: *** [all] Error 1
GISGEN failure at STEP: src/raster/r.combine

OK, I did a man and info on yylex and clear_input and got nothing.
Is there a reference somewhere that I can find out what these
are so I can 1. download the appropriate libraries, or 2, 
edit the source and use newer function calls if they are
obsolete.  (Hope this is a proper query for this board)

Thanks 
-- 
Cliff