XMLStarlet - XMLStarlet Command Line XML Toolkit
GNU sed - sed (stream editor) is a Unix utility that parses text and implements a programming language which...
xmllint - command line XML tool
TXR - Pragmatic, convenient data munging language.
SNR (Search-n-Replace) - SNR is a free Windows command-line utility that performs multiple string-replacement operations on a data file in a single pass.
GNU M4 - GNU M4 is an implementation of the m4 macro preprocessor.