How to install postgis 2.0 from sources on CentOS 6.2
==========================
Documentation:
http://postgis.refractions.net/documentation/manual-2.0/postgis_installation.html#id2799864
http://www.postgresql.org/docs/9.1/interactive/installation.html

Repositories:
http://yum.postgresql.org/
http://yum.postgresql.org/howtoyum.php
http://yum.postgresql.org/repopackages.php
==========================
Installation steps:
1-Install postgres repository
2-Install some PostGIS dependancies from the repository using yum
3-Install JSON-c from sources
4-Install Gdal from sources
5-Install Postgresql from sources
6-Install PostGIS from sources
7-Install postGIS sql functions

Note: Lines starting with "#//--" are comments
==========================
#//--Install postgres package repository
sudo rpm -Uvh http://yum.postgresql.org/9.1/redhat/rhel-6-x86_64/pgdg-centos91-9.1-4.noarch.rpm
sudo vi /etc/yum.repos.d/pgdg-91-centos.repo
exclude=postgresql*

#//--Install some PostGIS dependancies from the repository automatically
sudo yum install -y gcc.x86_64 make.x86_64 libxml2.x86_64 gcc-c++.x86_64 libxml2-devel-2.7.6-4.el6_2.4.x86_64 readline.x86_64 readline-devel.x86_64 geos-devel-3.3.4-1.rhel6.x86_64 proj-devel-4.7.0-1.rhel6.x86_64geos.x86_64 proj.x86_64;

#//--Install JSON-c from source code
wget http://oss.metaparadigm.com/json-c/json-c-0.9.tar.gz;
tar -xzvf json-c-0.9.tar.gz;
cd json-c-0.9
./configure
make
sudo make install

#//--Install Gdal from source code
wget http://download.osgeo.org/gdal/gdal-1.9.1.tar.gz;
tar -xzvf gdal-1.9.1.tar.gz;
cd gdal-1.9.1
./configure
make
sudo make install

#//--Install Postgresql from source code
wget http://ftp.postgresql.org/pub/source/v9.1.4/postgresql-9.1.4.tar.gz
./configure
gmake
su
sudo gmake install
(note: /usr/local/pgsql/bin should be inserted into /etc/profile)
adduser postgres
passwd postgres
mkdir -p /usr/local/pgsql/data
chown postgres:postgres /usr/local/pgsql/data

#//--Install PostGIS from source code
sudo echo '/usr/local/lib' >> /etc/ld.so.conf
sudo echo '/usr/lib' >> /etc/ld.so.conf
sudo echo '/usr/lib64' >> /etc/ld.so.conf
sudo ldconfig
wget http://www.postgis.org/download/postgis-2.0.0.tar.gz
tar -xvzf postgis-2.0.0.tar.gz
cd postgis-2.0.0
./configure
make
make comments
make cheatsheets
sudo make install
sudo make comments-install

#//--Create postgis database and install postGIS sql functions
cd /usr/local/pgsql/data
su postgres
pg_ctl -D . -l logfile stop
exit
sudo rm -rf ./*
su postgres
initdb -D .
pg_ctl -D . -l logfile start
cat logfile
createdb geocoder
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/postgis.sql  2>&1 | less
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/postgis_comments.sql  2>&1 | less
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/spatial_ref_sys.sql  2>&1 | less
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/rtpostgis.sql  2>&1 | less
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/raster_comments.sql  2>&1 | less
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/topology.sql  2>&1 | less
psql -d geocoder -f /usr/local/pgsql/share/contrib/postgis-2.0/topology_comments.sql  2>&1 | less