xml-validate
Validate XML documents.
TLDR
Validate one or more XML documents for well-formedness only
$ xml validate [path/to/input1.xml|URI] [input2.xml ...]
Validate one or more XML documents against a Document Type Definition (DTD)
$ xml validate --dtd [path/to/schema.dtd] [path/to/input1.xml|URI] [input2.xml ...]
Validate one or more XML documents against an XML Schema Definition (XSD)
$ xml validate --xsd [path/to/schema.xsd] [path/to/input1.xml|URI] [input2.xml ...]
Validate one or more XML documents against a Relax NG schema (RNG)
$ xml validate --relaxng [path/to/schema.rng] [path/to/input1.xml|URI] [input2.xml ...]
Display help for the validate subcommand
$ xml validate --help