quoting @ac_subst@ keywords

[Lars J. Aas]

I'm setting up my own sed-parse rule in a Makefile.in file, that
should do sustitutions the way config.status does, based on some
AC_SUBST keywords.  Obviously, I need to be able to quote the
search string, so the @ac_subst@ keyword is "intact" in the target
Makefile.  How do I do that?

e.g.
  sed 's/@keyword@/@keyword@/g' < input > output
         ^^^^^^^^^ must be quoted
becomes
  ???

Thanks in advance,

  Lars J