xmllint: Format and Validate XML on Unix

xmllint can be used in Unix to format and validate XML.

• How do I pretty format XML?
  xmllint --output newFile.xml --format oldFile.xml
  
  
• How do I use tabs instead of spaces to format XML?
  XMLLINT_INDENT=$'\t' xmllint --output newFile.xml --format oldFile.xml
  
  
• How do I validate an XML against a DTD?
  xmllint --dtdvalid http://java.sun.com/j2ee/dtds/web-app_2_2.dtd web.xml
  
  
• How do I validate against a XSD schema?
  xmllint --debugent --schema http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd web.xml