Mike Haertel wrote the main program and the dfa and kwset matchers. Arthur David Olson contributed the heuristics for finding fixed substrings at the end of dfa.c. Richard Stallman and Karl Berry wrote the regex backtracking matcher. Henry Spencer wrote the original test suite from which grep's was derived. Scott Anderson invented the Khadafy test. David MacKenzie wrote the automatic configuration software use to produce the configure script. Authors of the replacements for standard library routines are identified in the corresponding source files. The idea of using Boyer-Moore type algorithms to quickly filter out non-matching text before calling the regexp matcher was originally due to James Woods. He also contributed some code to early versions of GNU grep. Mike Haertel would like to thank Andrew Hume for many fascinating discussions of string searching issues over the years. Hume & Sunday's excellent paper on fast string searching (AT&T Bell Laboratories CSTR #156) describes some of the history of the subject, as well as providing exhaustive performance analysis of various implementation alternatives. The inner loop of GNU grep is similar to Hume & Sunday's recommended "Tuned Boyer Moore" inner loop. More work was done on regex.[ch] by Ulrich Drepper and Arnold Robbins. Regex is now part of GNU C library, see this package for complete details and credits. Arnold Robbins contributed to improve dfa.[ch]. In fact it came straight from gawk-3.0.3 with small editing and fixes. Many folks contributed see THANKS, if I omited someone please send me email. Alain Magloire is the current maintainer.