See $subject.

I run a command as:

set cmd [open "|command"]

Eventually, I close it. As one does.

How do I get the exit status (?$ in bash or %errorlevel% in dos) from 'command'? In the samples I see, they use:

catch {close $cmd} results options

The claim is that this should contain the information from the command run in the pipe.

I do not seem to get this. I'm testing on Windows.

If I run 'command' at the prompt, I see that it exits with, say, 5 (which makes sense for the command). What I get in the results is a code of 1, and typically something like "command exited unexpectedly". I do not see it doing that when run directly.

Have I missed some critical point?

The reason I am doing it as a pipe is that it can be a very long running command, and I want the Tcl program that calls it to still be active. And I want access to whatever it prints. That part is working. It seem to properly detect when the pipe is closed (eof $cmd).

I'm basing my code on

https://wiki.tcl-lang.org/page/Execute+in+Parallel+and+Wait

Aside from getting the exit status, the code seems to work. Except I think the "catch [close $cmd] r o" should use curly brackets. I did try that to see if there was some voodoo thing going on. It made no difference.

Can I get the exit status of the command somehow?

--
Roger

On Friday, May 5, 2023 at 1:00:07 PM UTC+2, Roger Oberholtzer wrote:
> See $subject.
>
> I run a command as:
>
> set cmd [open "|command"]
>
> Eventually, I close it. As one does.
>
> How do I get the exit status (?$ in bash or %errorlevel% in dos) from 'command'? In the samples I see, they use:
>
> catch {close $cmd} results options
>
> The claim is that this should contain the information from the command run in the pipe.
>
> I do not seem to get this. I'm testing on Windows.
>
> If I run 'command' at the prompt, I see that it exits with, say, 5 (which makes sense for the command). What I get in the results is a code of 1, and typically something like "command exited unexpectedly". I do not see it doing that when run directly.
>
> Have I missed some critical point?
>
> The reason I am doing it as a pipe is that it can be a very long running command, and I want the Tcl program that calls it to still be active. And I want access to whatever it prints. That part is working. It seem to properly detect when the pipe is closed (eof $cmd).
>
> I'm basing my code on
>
> https://wiki.tcl-lang.org/page/Execute+in+Parallel+and+Wait
>
> Aside from getting the exit status, the code seems to work. Except I think the "catch [close $cmd] r o" should use curly brackets. I did try that to see if there was some voodoo thing going on. It made no difference.
>
> Can I get the exit status of the command somehow?

Ok. Bad form answering your own question. But I see that if the -code is 1 (TCL_ERROR) one should look at -errorcode for more information. I knew this from the mists of time. Anyway, if I look there I find what I am looking for.

Thanks Roger for that splendid answer!