Select Output in XML format

Dear all,

Today I need to write the output of an postgres table into XML format.
I think there is an easiest way to do this but not able to find it.

In mysql there is simple query for that :

mysql -X -e "select * from db_name.master" > /hdd2-1/test.xml

In postgres , i find some XML data types but how we can put our select
output into xml file.

Thanks