Xidel - Xidel is a command line tool to download html/xml pages and extract data from them using CSS 3 selectors, XPath 3 expressions or pattern-matching templates.
xmllint - command line XML tool
XMLStarlet - XMLStarlet Command Line XML Toolkit
TXR - Pragmatic, convenient data munging language.
Bracmat - Programming language for symbolic computation with extraordinary combination of pattern matching...