Martijn Dekker <mart...@inlv.org> wrote:
> Op 02-08-17 om 22:17 schreef Thorsten Glaser:
> > Robert Elz dixit:
> >
> >> The only way that the standard will ever say that "exec fn" is possible
> >> (exec builtin is supposed to be possible now, as (almost) all builtins
> >> are supposed to have exec*(2) versions somewhere in $PATH) is if at least
> >
> > I repeat: the exec builtin does *not* have anything to do with
> > requiring the C code of the shell (could be COBOL for all I know)
> > to actually call an exec*(2) syscall.
>
> Actually, we have word from Geoff Clare, who is authoritative on this
> matter, that the intention of POSIX was to standardise the pre-existing
> behaviour of ksh88.[*]
>
> As both Geoff and I have verified with our own copies of ksh88 (mine on
> a Solaris 10.3 VM), 'exec' on ksh88 always overlays the shell process
> with an external command using an exec*(2) syscall. It never runs a
> shell function or a builtin.
And since this is the same behavior as seen with a traditional Bourne Shell,
and ksh93, this is obviously the "right" method.
> Another fact is that pdksh was intended to be a clone of ksh88. Thus,
> pdksh failed to clone ksh88's 'exec' properly.
There are several deviations between mksh and ksh88. Some of them could
be seen as bugs.
Jörg
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