As we get progressively more used to XML in our Web applications we're finding that what we need is a whole range of tools to manipulate XML content. Today, I have a really interesting tool to do just that: XMLStarlet, an open source freeware released under the MIT license, which means that the software can be used and distributed in both commercial and non-commercial projects. (More licensing facts.)XMLStarlet is a command line utility that can:* Check or validate XML files through a simple well-formedness check, DTD, XSD, or RelaxNG, a schema language for XML.XPath expressions on XML files.XSLT stylesheets to XML documents including EXSLT support\u00a0and passing parameters to stylesheets.Xinclude.XML c14n canonicalization.PYX format and vice versa.* Calculate values of * Search XML files for matches to given XPath expressions.* Apply * Query XML documents.* Modify or edit XML documents.* Format or "beautify" XML documents.* Fetch XML documents using http:\/\/ or ftp:\/\/ URLs* Browse tree structure of XML documents (similar to the 'ls' command).* Include one XML document into another using * * Escape or unescape special XML characters in input text.* Print a directory as an XML document.* Convert XML into The XmlStarlet User's Guide is available in a descriptive HTML version, as well as in PDF, and plain text. Between these documents, this is a thorough description of the syntax of XMLStarlet commands with enough examples to get you started. There's also a helpful IBM article on the ins and outs of the program.This is a powerful tool and even better, it is available for download onto Linux, SunOS and Windows.