Examples shp2pgsql

shp2pgsql -s <SRID> shapefile nameoftable > sqlfileforimport.sql

shp2pgsql -s 26986 cities tblcities > cities.sql

In the above we are outputting an shp file called cities.shp to a table tblcities and dumping the sql insert statements to a file called cities.sql. The Spatial Ref system is 26986 (which if you look in spatial_ref_sys is Massachusetts State Plane NAD 83 meters).