XMLStarlet - XMLStarlet Command Line XML Toolkit
xmllint - command line XML tool
GNU M4 - GNU M4 is an implementation of the m4 macro preprocessor.
GNU sed - sed (stream editor) is a Unix utility that parses text and implements a programming language which...
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.
Gema - General purpose text macro processor.