Wikipedia
PDGREPPE
PDGREPPE is a text editor for personal computers that feature MS-DOS.
PDGREPPE is also an acronym for Pattern Definition GREP Pattern Editor.
It is a high-speed MS-DOS command line search-and-replace text editor that uses Extended Regular Expressions (ERE's). Both the search pattern and replace pattern are based on these ERE's and, like other standard computer text editors, can perform search, match and replace actions more effective than literal search patterns.
PDGREPPE can be used with MS-DOS versions 2.0 to version 7.0. It can also operate in MS-DOS command line, batch file or embedded mode in Microsoft Windows.