They're in the PostgreSQL source distribution:
https://github.com/postgres/postgres/tree/master/src/tutorial
Aside: the latest PostgreSQL is 9.3, not 9.1:
http://www.postgresql.org/docs/current/static/tutorial-sql-intro.html
Question
I have installed postgresql on my ubuntu machine using,
apt-get install postgresql-9.1
Now I am reading the manual however could not figure out where the tutorial files (e.g., basics.sql) are.
Where can I find or download them?
Solution
They're in the PostgreSQL source distribution:
https://github.com/postgres/postgres/tree/master/src/tutorial
Aside: the latest PostgreSQL is 9.3, not 9.1:
http://www.postgresql.org/docs/current/static/tutorial-sql-intro.html