title: PostGIS: Create Extension failed
body: <p>I ran command in psql:</p>
  
  <pre><code>my-spatial-db=# CREATE EXTENSION postgis;
  </code></pre>
  
  <p>and get error:</p>
  
  <pre><code>ERROR:  could not open extension control file "/usr/share/pgsql/extension/postgis.control": No such file or directory
  
  my-spatial-db=# select postgis_full_version();
  NOTICE:  Function postgis_gdal_version() not found.  Is raster support enabled and rtpostgis.sql installed?
  NOTICE:  Function postgis_topology_scripts_installed() not found. Is topology support enabled and topology.sql installed?
  NOTICE:  Function postgis_raster_scripts_installed() not found. Is raster support enabled and rtpostgis.sql installed?
  NOTICE:  Function postgis_raster_lib_version() not found. Is raster support enabled and rtpostgis.sql installed?
                                   postgis_full_version                                      
  -----------------------------------------------------------------------------------------------
   POSTGIS="2.0.2 r10789" GEOS="3.3.6-CAPI-1.7.6" PROJ="Rel. 4.8.0, 6 March 2012" LIBXML="2.9.1"
  
  
  my-spatial-db=# select version();
                                                     version                                                   
  -------------------------------------------------------------------------------------------------------------
  PostgreSQL 9.2.7 on x86_64-redhat-linux-gnu, compiled by gcc (GCC) 4.8.2 20131212 (Red Hat 4.8.2-7), 64-bit
  </code></pre>
  
  <p>I installed PostGIS from .tar since my os is AWS EC2 Amazon Linux(doesn't have build-in postgis package in yum)</p>
  
  <p>I also ran these two commands:</p>
  
  <pre><code>psql -d my-spatial-db -f /usr/share/pgsql/contrib/postgis-2.0/postgis.sql
  psql -d my-spatial-db -f /usr/share/pgsql/contrib/postgis-2.0/spatial_ref_sys.sql
  </code></pre>
  
  <p>Am I missing something? Thanks very much!</p>