On Tue, Jan 14, 2025, at 5:51 AM, Geoff Clare via austin-group-l at The Open
Group wrote:
>
> [...]
>
> If any file descriptors with numbers greater than 2 are opened by
> those redirections, it is unspecified whether those file
> descriptors remain open when the shell invokes another utility.
>
> [...]
>
> So I think his specific use case is not a problem; however I think
> his mail has brought to light a mismatch between the POSIX wording and
> implementations. As I understand it, in ksh this is implemented by
> setting FD_CLOEXEC on file descriptors greater than 2 when opened by
> "exec". This means it would never affect built-in utilities, so I
> think a better match would be:
>
> ..., it is unspecified whether those file descriptors remain open
> when the shell invokes a non-built-in utility.
>
> I can't think of any built-ins in POSIX that have the ability to access
> a specified fd, but it would matter if we ever want to add "read -u" to
> the standard.
Does built-in "test -t" count? Does this have unspecified behavior?
exec 3>&1
test -t 3
--
vq
