Installation of Postgis/postgresql

Trying to install postgis on LINUX machine, need to find the geos-
config file, as seems it is no where to be found after download of
postgis in the ./configure step, is there anyone that can give me a
clue on how to find this file? Ultimate goal is to get postgis working
so we can use geom data type in the tables on postgresql, and to get
php to be able to talk to postgresql when scripts are run using
pg_connect function.

during ./configure of postGIS errors out looking for geos-config

during ./configure of geos errors out looking for g++

to the best of my knowledge g++ is part of gcc and we have a current
version of the gcc compiler on the computer

Thanks,
Nick