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.
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