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

[Ken Thompson via TUHS]

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.


On Tue, Sep 23, 2025 at 5:14 AM Don Caldwell via TUHS <tuhs at tuhs.org> wrote:

> It was definitely Andrew Hume. While at Shannon Labs, he was promoting and
> using it for some of his projects.
>
> On Tue, Sep 23, 2025 at 12:59 AM Noel Hunt via TUHS <tuhs at tuhs.org> wrote:
>
> > I will tentatively suggest that it was Andrew Hume. I suspect
> > his major contribution was the addition of Boyer-Moore.
> >
> >
> > On Tue, 23 Sept 2025 at 04:38, Thalia Archibald via TUHS <tuhs at tuhs.org>
> > wrote:
> >
> > > Spurred by the discussion on regular expressions in the Forth thread:
> > >
> > > Unix V10 included a command named gre, which aimed to succeed grep,
> > egrep,
> > > and
> > > fgrep.
> > >
> > > Does anyone know anything about it? Who wrote it? Was it used anywhere
> or
> > > succeeded by anything? Was it connected to Plan 9 or Inferno?
> > >
> > > From its man page:
> > > > Gre supplants three classic programs, which are still available:
> > > > Grep handles only ed(1)-like regular expressions. It uses \(\)
> instead
> > > of ().
> > > > Egrep handles the same patterns as gre except for back-referencing
> with
> > > \1, \2, ...
> > > > Fgrep handles no operators except newline (alternation).
> > >
> > > https://www.tuhs.org/cgi-bin/utree.pl?file=V10/cmd/gre
> > > https://www.tuhs.org/cgi-bin/utree.pl?file=V10/man/man1/gre.1
> > >
> > > Thanks,
> > > Thalia Archibald
> > >
> >
>