This zip file contains source code described in 

PostGIS in Action, 2nd Edition

The files with .sql extensions are examples that should be run in psql or pgAdmin query windows.
The ones that end in _commandline.txt should be run at command prompt.

For updates to these files, Please refer to the book site

http://www.postgis.us/chapters_edition_2  (the paper clips denote chapters with code and data downloads)