XMLStarlet is a set of command line utilities (tools) to transform, query, validate, and edit XML documents and files using simple set of shell commands in similar way it is done for text files with UNIX grep, sed, awk, diff, patch, join, etc utilities.
Shell.NET is a set of console and winform applications written in C#. It features nearly 100 applications ranging from classical Unix applications like basename, cal, grep, tr, uniq, and wc, to some very unique tools like RunScript or TextTransform.
rtgrep is a bash script which searches for all files in the current directory or a given base directory which were created/modified within a given time period. The search can be recursive, and you can specify a pattern to be matched in the file contents