Building just PostGIS shp2pgsql and raster2pgsql on Ubuntu

postgis_client_tools_ubuntu

apt-get update
apt-get install postgresql-client-9.6 postgresql-server-dev-9.6

#if no postgresql found check what version of Ubuntu you are running 
lsb_release -a

#mine read xenial 16.04
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt xenial-pgdg main" >> /etc/apt/sources.list'
wget --quiet -O - http://apt.postgresql.org/pub/repos/apt/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update
apt-get install postgresql-client-9.6 postgresql-server-dev-9.6
#if you don't need to build raster2pgsql you can leave out libgdal-dev

apt-get install libproj-dev libgdal-dev libgeos-dev libxml2 gcc 


mkdir projects
cd projects 
wget http://download.osgeo.org/postgis/source/postgis-2.3.3.tar.gz
tar -xvf postgis-2.3.3.tar.gz
cd postgis-2.3.3
#in theory adding --prefix=some-path to ./configure should allow you to install shp2pgsql/raster2pgsql 
# where you want Ubuntu seems to override or could be bug in PostGIS
./configure

#if you don't need to build raster2pgsql you can do below instead of full ./configure
./configure --without-raster

cd liblwgeom
make && make install
cd ../loader
make && make install
#note that shp2pgsql is installed in /usr/lib/postgresql/9.6/bin
ldconfig 
#to test
/usr/lib/postgresql/9.6/bin/shp2pgsql  #gives help screen


cd ../raster/loader
make && make install
#note gets installed here
/usr/lib/postgresql/9.6/bin/raster2pgsql

#run (should give you help)
/usr/lib/postgresql/9.6/bin/raster2pgsql