[Gdal-dev] convert a group of points (lat, lon) to a shape file

[Xiaodong Zhang]

Hi,

I have a humble question which may have been answered before, but could 
anybody please kindly help out. The question is:

If I have a series of points, say in a text file, like
lat1, lon1
lat2, lon2
lat3, lon3
lat4, lon4

How should I format the text file such that an ogr utility (e.g., 
ogr2ogr) can convert it into a shapefile as a polygon.

Many thanks
Xiaodong