install.txt

Ubuntu 15.04
sudo apt-get install postgresql-9.4-postgis-2.1 postgis-doc postgresql-doc pgadmin3

Ubuntu 14.04
sudo apt-get install postgresql-9.3-postgis-2.1 postgis-doc postgresql-doc pgadmin3 postgresql-server-dev-9.3

...
Setting up postgresql-9.3 (9.3.6-0ubuntu0.14.04) ...
Creating new cluster 9.3/main ...
  config /etc/postgresql/9.3/main
  data   /var/lib/postgresql/9.3/main
  locale en_US.UTF-8
  port   5432
...

sudo -u postgres psql postgres
\password postgres
\q

psql -h localhost -U postgres
create extension adminpack;
create database postgis;

psql -h localhost -U postgres postgis
create extension postgis;
create extension postgis_topology;

CREATE TABLE locations(loc_id integer primary key, loc_name varchar(70), geog geography(POINT));
CREATE INDEX locations_gix ON locations USING GIST(geog);

INSERT INTO locations(loc_id, loc_name, geog) VALUES
  (0, 'Vila do Rossio, Sao Paulo, SP', ST_GeogFromText('POINT(-46.759648 -23.643439)')),
  (1, 'UOL, Sao Paulo, SP', ST_GeogFromText('POINT(-46.691784 -23.569582)')),
  (2, 'Ladrillo, Sao Paulo, SP', ST_GeogFromText('POINT(-46.671072 -23.604196)')),
  (3, 'Shopping Jardim Sul, Sao Paulo, SP', ST_GeogFromText('POINT(-46.735837 -23.630906)'));

COMMIT;

SELECT loc_id, loc_name, ST_AsGeoJSON(geog)::json as loc_json FROM locations;

SELECT * FROM locations WHERE ST_DWithin(geog, ST_GeogFromText('SRID=4326;POINT(-46.759648 -23.643439)'), 5000);