xmllint

XML parser and linter that supports XPath, a syntax for navigating XML trees. More information: https://manned.org/xmllint.

• 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}}