Re: zsh vs. ksh coproc redirection semantics

Re: zsh vs. ksh coproc redirection semantics

[Andrew Main]

Bart Schaefer wrote:
>(Is anybody on zsh-workers reading this?  Zefram, Zoltan, Peter?)

Yes.  My current plan is to ignore the debate, and go for the full-on
zsh solution: by default, >&p and <&p act as if p were a normal file
descriptor referring to the appropriate pipe, as zsh does now; at the
drop of an option, we do whatever ksh does, if it's different.

Can someone who knows one end of a pipe from the other please experiment
with ksh and definitively state what it does?  I'd like information on
pdksh, ksh88 and ksh93.  If only one of them has behaviour inconsistent
with zsh then it's probably a bug and therefore not worth emulating.

-zefram

Re: zsh vs. ksh coproc redirection semantics

[Bart Schaefer]

On May 6,  5:52pm, Andrew Main wrote:
> Subject: Re: zsh vs. ksh coproc redirection semantics
> Bart Schaefer wrote:
> >(Is anybody on zsh-workers reading this?  Zefram, Zoltan, Peter?)
> 
> Yes.  My current plan is to ignore the debate, and go for the full-on
> zsh solution: by default, >&p and <&p act as if p were a normal file
> descriptor referring to the appropriate pipe, as zsh does now; at the
> drop of an option, we do whatever ksh does, if it's different.

That doesn't address the issue of how to close the coproc input in the
basic zsh model.  Is "coproc exit" really going to be the approved way?

Re: zsh vs. ksh coproc redirection semantics

[Andrew Main]

Bart Schaefer wrote:
>That doesn't address the issue of how to close the coproc input in the
>basic zsh model.  Is "coproc exit" really going to be the approved way?

That's a separate issue.  I think the best solution is tied into access
to file descriptors above 9: make the coprocess fds be 10 and 11, and
then you can do (ignoring for the moment the single digit restriction of
the syntax) "10>&- 11>&-" to close them.  ">&p" would be shorthand for
">&10", and so on.

What syntax to use for these fds is another issue altogether.  We're
seriously short of special characters, and I don't see a good syntax
that's compatible with POSIX.  (The best I see is to put ">;" preceding
the multi-digit version of the normal syntax.)  OTOH, it would probably
be reasonably easy to simply allow multi-digit fd numbers with an option,
enabled by default only in zsh mode.

-zefram