Re: [BUG] 'exec' runs shell functions and builtins

[Kamil Dudka <kdudka@redhat.com>]

On Friday, July 28, 2017 10:58:59 Bart Schaefer wrote:
> On Thu, Jul 27, 2017 at 2:02 AM, Peter Stephenson
> 
> <p.stephenson@samsung.com> wrote:
> > % (setopt posixbuiltins; exec command echo foo)
> > zsh: command not found: command
> 
> Chet Ramey emailed me:
> =====
> "However, all of the standard utilities, including the regular built-ins in
> the table, but not the special built-ins described in Special Built-In
> Utilities, shall be implemented in a manner so that they can be accessed
> via the exec family of functions as defined in the System Interfaces volume
> of POSIX.1-2008 and can be invoked directly by those standard utilities
> that require it (env, find, nice, nohup, time, xargs)."
> 
> `command' is explicitly listed in the table in
> 
> http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap01.html#tag
> _17_06 =====
> 
> So "exec command ..." is actually supposed to work, as is "exec read",
> "exec getopts", etc.  Urk.

Today I discovered that bash in Fedora installs /usr/bin/cd and the like
as external commands to make 'exec' work on those built-ins (primarily
in bash):

https://bugzilla.redhat.com/820192

I am really not happy about this solution because the external commands
only confuse people for no good reason (other than satisfying the POSIX 
requirement).

It is good that zsh does not need this in its native configuration but
how is it supposed to work in the POSIX emulation mode now?

% (exec cd)
% emulate sh
% (exec cd) 
zsh: command not found: cd

If I understand http://www.zsh.org/mla/workers/2017/msg01138.html correctly,
then the above command should work?

Kamil