'cmd /C start cmd' no longer non-blocking (base-cygwin 3.1-1), but used to work (in base-cygwin 3.0-1)

Buchbinder, Barry (NIH/NIAID) [E] BBuchbinder@niaid.nih.gov
Sat May 5 22:44:00 GMT 2012

Andrey Repin sent the following at Saturday, May 05, 2012 7:31 AM
> On 5/4/2012 3:43 PM, Petrisor Eddy-Marian-B36037 wrote:
>> I am using at work cygwin on various machines (XP and Windows 7) and made
>> several scripts that use gnu utilities from cygwin. One of those is a script
>> that starts in paralel instances of cmd various parts of a build system
>> through a sh script that invokes 'cmd /C start ...'
>Why? Aren't your default ComSpec isn't CMD already?
>> to start those parts of the build system in a non-blocking fashion.
>If it's (b?a|tc)?sh script - use backgrounding (The &) If it's a CMD
>script - use backgrounding (START "" /B "command" args) Problem solved.
>> Recently, on one of the machines which had its cygwin installation upgraded,
>> I have observed that the cmd instances do not start in a non-blocking
>> fashion anymore, but instead wait for the process to finish.
>> To be more precise, following the following steps should lead to two
>> interactive windows, one with the sh prompt and one with the cmd prompt,
>> both waiting for user input:
>> 1 - start a cygwin (or sh) command window
>> 2 - type "cmd /C start cmd"
>> Expected result:
>> Two interactive and usable windows, one with the sh prompt, one with the cmd
>> prompt, both waiting for user input.
>For new interactive windows from withing Cygwin shell - use run program.
>And again, backgrounding, if necessary.
>> Actual result:
>> Two windows, one with sh and one with cmd, Cygwin/sh window blocked and
>>waiting for the cmd window to finish.

Question #1:

Why not use cygstart?

The only reason I ever use cmd /c start is to use the /wait option of start,
which is exactly not what you want.  (Indeed, I wouldn't mind it if a --wait
option was added to cygstart.  Hint.  Hint.)

Question #1.1:

Are you using the /wait option of cmd /c start?

Question #2:

Is there a reason that cygstart wasn't suggested earlier?

(That's not intended as a criticism.  I just want to know why in case there
was one.)


- Barry
  Disclaimer:  Statements made herein are not made on behalf of NIAID.

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