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.
GPP - GPP is a general-purpose preprocessor with customizable syntax, suitable for a wide range of...
xmllint - command line XML tool
Gema - General purpose text macro processor.
XMLStarlet - XMLStarlet Command Line XML Toolkit
TXR - Pragmatic, convenient data munging language.