mintty: WINCH-signal to child

mintty: WINCH-signal to child

[Helmut Karlowski]

When I run for example an editor from a shell in a mintty-window and  
change the window-size the editor is informed by a WINCH-signal. That is  
good. But the shell it was started from does not know about the change, so  
after exiting the editor the shell uses the old size. Could mintty send a  
WINCH-signal to its direct child (-pgrp) perhaps?

Of course for more complicated situations it could be difficult to inform  
all involved processes when not all have the same pgrp, but it would be  
better than nothing.

Or do I miss something?

-Helmut

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Re: mintty: WINCH-signal to child

[Duncan Roe]

On Sat, Oct 18, 2014 at 10:02:33PM +0100, Helmut Karlowski wrote:
>
> When I run for example an editor from a shell in a mintty-window and change
> the window-size the editor is informed by a WINCH-signal. That is good. But
> the shell it was started from does not know about the change, so after
> exiting the editor the shell uses the old size. Could mintty send a
> WINCH-signal to its direct child (-pgrp) perhaps?
>
> Of course for more complicated situations it could be difficult to inform
> all involved processes when not all have the same pgrp, but it would be
> better than nothing.
>
> Or do I miss something?
>
> -Helmut
>
bash at least has "shopt -s checkwinsize" to achieve what you want,

Cheers ... Duncan.

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Re: mintty: WINCH-signal to child

[Helmut Karlowski]

Am 19.10.2014, 09:48 Uhr, schrieb Duncan Roe:

> bash at least has "shopt -s checkwinsize" to achieve what you want,

That would be a workaround for bash. Ideally every process should forward  
the WINCH-signal to its parent, or the terminal should walk through the  
call-tree. Both not very likely to happen.

xterm does the same as mintty BTW.

Thanks,

Helmut

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Re: mintty: WINCH-signal to child

[Thomas Wolff]

Am 19.10.2014 12:11, schrieb Helmut Karlowski:
> Am 19.10.2014, 09:48 Uhr, schrieb Duncan Roe:
>
>> bash at least has "shopt -s checkwinsize" to achieve what you want,
>
> That would be a workaround for bash. Ideally every process should 
> forward the WINCH-signal to its parent, or the terminal should walk 
> through the call-tree. Both not very likely to happen.
>
> xterm does the same as mintty BTW.
There must be something more about it:
Mined does resend a received SIGWINCH to its parent (as an application 
should indeed) and it's actually received by bash as can be confirmed 
with 'trap "echo WINCH" SIGWINCH'. Despite of the received signal bash 
does not adapt its command line width assumption (as can be checked by 
typing a long line and seeing where it wraps) (unless that option is 
enabled).
Probably a bash bug.
Same in mintty as in xterm in all cases.
Same on Linux (bash 3.2.39 on Debian on PowerPC), so not cygwin-specific.
------
Thomas

>
>
> Thanks,
>
> Helmut
>
> -- 
>
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Re: mintty: WINCH-signal to child

[Linda Walsh]

Thomas Wolff wrote:
> Am 19.10.2014 12:11, schrieb Helmut Karlowski:
>> Am 19.10.2014, 09:48 Uhr, schrieb Duncan Roe:
>>
>>> bash at least has "shopt -s checkwinsize" to achieve what you want,
>>
>> That would be a workaround for bash. Ideally every process should 
>> forward the WINCH-signal to its parent, or the terminal should walk 
>> through the call-tree. Both not very likely to happen.
>>
>> xterm does the same as mintty BTW.
> There must be something more about it:
> Mined does resend a received SIGWINCH to its parent (as an application 
> should indeed) and it's actually received by bash as can be confirmed 
> with 'trap "echo WINCH" SIGWINCH'. Despite of the received signal bash 
> does not adapt its command line width assumption (as can be checked by 
> typing a long line and seeing where it wraps) (unless that option is 
> enabled).
> Probably a bash bug.
> Same in mintty as in xterm in all cases.
> Same on Linux (bash 3.2.39 on Debian on PowerPC), so not cygwin-specific.
----
Do you guys also know there was a change between 4.2 and 4.3 in bash's 
signal handling?  In 4.2, bash used to do child processing inside the 
parent interrupt
which caused problems.  In 4.3, bash waits until a key is pressed before
propagating any signals.

This may be unrelated to whatever problem you are experiencing, but I 
thought
I'd mention you might goog the bash archives on sigwinch and/or winch... 
(not
sure what would be the exact right invocation, but it may not be related
to what you are experiencing anyway...


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