Command echo

[Andrew DeFaria]

On 11/16/2015 08:40 AM, Buchbinder, Barry (NIH/NIAID) [E] wrote:
> Gluszczak, Glenn sent the following at Monday, November 16, 2015 11:16 AM
>>
>> When I shell to cmd.exe, the commands I execute are echoed (not sure if
>> stdout or stderr). This doesn't happen under native cmd.exe. Is there a
>> variable that controls this? I only have CYGWIN=nodosfilewarning
>>
>> Notice the commands "dir" and "whoami" are emitted to the output.
>
> cmd.exe is in control of its own echoing.  Try starting as cmd /q
> cmd /?
> ...
> /Q      Turns echo off
> ...
>
> As to why cmd behaves differently when started under bash (even in a
> non-mintty window) than when started directly or under cmd ....
>
> Hope that helps.
>
> - Barry
>    Disclaimer: Statements made herein are not made on behalf of NIAID.

Mintty (and ssh, etc.) use pty's. cmd does not understand pty's. So if 
you run say Cygwin's bash from a cmd window and then start cmd you will 
not get the echoing. If, however, you start cmd from a bash shell that 
is in a mintty window then you're using pty's and you'll get echoing. 
Likewise if you run bash in a cmd window, then say ssh to another 
machine, you're now using pty's and you'll see the behavior again.
-- 
Andrew DeFaria
http://defaria.com


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