[TUHS] Unix gre, forgotten successor to grep (was: forth on early unix)

[Thalia Archibald via TUHS]

Ken,

Your email reminds me of a comment you made in a 1989 interview with Mike
Mahoney, that suggests something earlier than QED:

> I did a lot of compiling. Even in college and out of college I did a lot of
> on-the-fly compilers. Ah. ah. I wrote a GREP-like program. It would... You
> type in …, you’d say what you wanted it to look for, and a sed-like thing
> also. That you’d say, I want to do a substitute of A for B or some block of
> text. What it would do is compile a program that would look for A and
> substitute in B and then run the compiled program so that one level removed
> from it do I direct my (unclear) and the early languages, the regular
> expression searching stuff in ED and its predecessors on CTSS and those things
> were in fact compilers for searches. They in fact compiled regular...

https://www.tuhs.org/Archive/Documentation/OralHistory/transcripts/thompson.htm

By anyone's history of regular expressions, your matcher in QED was the first
software implementation of regular expressions. Was this grep-like program you
wrote in college something earlier than that? Could you share more about it? Do
you somehow still have the source for these? I'd love to study it.

Thalia

On Sep 23, 2025, at 11:40, Ken Thompson wrote:
> i think the plan9 grep is the fastest.
> it is grep, egrep, fgrep also.
> i think it is faster than boyer-moore.
> the whole program is a jit dfa
> 
>   read block
>   for c in block
>   {
>      s=s.state[c]
>      if s == nil do something occasionally
>   }
> 
> it is a very few cycles per byte. all of the
> time is reading a block. i cant imagine b/m
> could be faster. the best b/m could do is
> calculate the skip and then jump over
> bytes that you have already read.
> 
> 
> russ cox used it to do the (now defunct) code
> search in google.