Suppose you want to create a xsd based on an "example.xml" structure.
After download and extract trang you can run it with:

java -jar /trang.jar example.xml example.xsd

The "example.xsd" file generated may not be exactly what you need, but most of the time it is a good starting point.

To validate a xml file, for instance "example.xml", against an xsd file,
"example.xsd", you can use the following command:

xmllint --schema form.xsd ~/form.xml