# xmllint > XML parser and linter that supports XPath, a syntax for navigating XML trees. > More information: . - Return all nodes (tags) named "foo": `xmllint --xpath "//{{foo}}" {{source_file.xml}}` - Return the contents of the first node named "foo" as a string: `xmllint --xpath "string(//{{foo}})" {{source_file.xml}}` - Return the href attribute of the second anchor element in an HTML file: `xmllint --html --xpath "string(//a[2]/@href)" webpage.xhtml` - Return human-readable (indented) XML from file: `xmllint --format {{source_file.xml}}` - Check that an XML file meets the requirements of its DOCTYPE declaration: `xmllint --valid {{source_file.xml}}` - Validate XML against DTD schema hosted online: `xmllint --dtdvalid {{URL}} {{source_file.xml}}`