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

[Peter Stephenson <p.stephenson@xxxxxxxxxxx>]

On Wed, 26 Jul 2017 10:46:06 -0700
Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
> AFAIK zsh has always had this behavior.  It also allows for example
> "exec builtin echo" as well as "builtin exec echo" etc.  What would
> POSIX say that
>     exec command echo foo
> should do?  It's relatively easy to stop "exec" from finding functions
> and builtin commands, but I think fairly painful to get it to ignore
> other "precommand modifier" tokens.  Even after PWS's 41464 the above
> example runs /bin/echo whereas I think the POSIX expectation would be
> to report "command: command not found".

This isn't what I get:

% (setopt posixbuiltins; exec command echo foo)
zsh: command not found: command
% cat ~/bin/builtin
#!/bin/sh
echo External command named $0
% (setopt posixbuiltins; exec builtin echo)
External command named /export/home/pws/bin/builtin

There's no further processing of the arguments when we find an exec
with posixbuiltins set, so the above is what I'd expect.

pws

diff --git a/Doc/Zsh/builtins.yo b/Doc/Zsh/builtins.yo
index 99b1dd4..0e8580d 100644
--- a/Doc/Zsh/builtins.yo
+++ b/Doc/Zsh/builtins.yo
@@ -679,7 +679,10 @@ See ifzman(the section `Precommand Modifiers' in zmanref(zshmisc))\
 ifnzman(noderef(Precommand Modifiers)).
 
 If the option tt(POSIX_BUILTINS) is set, var(command) is never
-interpreted as a shell builtin command or shell function.
+interpreted as a shell builtin command or shell function.  This
+means further precommand modifiers such as tt(builtin) and
+tt(noglob) are also not interpreted within the shell.  Hence
+var(command) is always found by searching the command path.
 
 cindex(redirection, current shell's I/O)
 If var(command) is omitted but any redirections are specified,