Date:        Fri, 14 Feb 2003 21:38:59 -0500
    From:        "Steven M. Bellovin" <smb@research.att.com>
    Message-ID:  <20030215023859.333377B4D@berkshire.research.att.com>

  | Which suggests that I should have done a 'make cleandir' before the 
  | build.sh, rather than before the 'cvs update'.  That seems reasonable

No, when you did the "cvs update" grep's Makefile changed to one for
which "make cleandir" would no longer work (effectively anyway).
That's why it needed to be run before the cvs update.

  | -- I got it to work by 'rm -rf /usr/obj'.

That's a superset of "make cleandir"....

There's no mention of the grep change in UPDATING - there should be.
Of course, here, that would have been too late - as UPDATING is
typically updated at the same time as everything else - that is, by
the time you saw there (if it was there at all) that you should
run "make cleandir" before a "cvs update" you would already have
done the latter (at which point manual rm commands are the only solution).

In any case, "make clean" (or more dramatic variants) should *never*
be required for software to build (unless the problem is insufficient
free space I guess).

Whenever that's suggested as the fix to a problem, someone should file
a PR noting a bug in the Makefile.

kre