Request for help debugging screen problem

Corinna Vinschen corinna-cygwin@cygwin.com
Mon Feb 8 09:51:00 GMT 2010


On Feb  7 16:09, Shaddy Baddah wrote:
> Hi,
> 
> On 7/02/2010 3:48 PM, Shaddy Baddah wrote:
> >However, I now have a new problem. Say I have no screen sessions running
> >at all:
> >
> >shaddy@*** ~
> >$ screen -r
> >There is no screen to be resumed.
> >
> >But I try an strace:
> >
> >shaddy@*** ~
> >$ strace -o /tmp/screen-r+cygserver-down.strace screen -r
> >23025 [main] screen 5340 C:\software\cygwin\bin\screen.exe: *** fatal
> >error - couldn't initialize fd 0 for /dev/tty2
> >
> >I've completely lost faith in my strace scenarios now. This last
> >scenario is how I came to determine that screen was trying to call
> >OpenProcess() on the cyg_server owned sshd process. I was intending to
> >mention it as it as it was unusual.
> >
> >Why doesn't this last strace just output the same "There is no screen to
> >be resumed." message? I am now hesistant to go on using strace, as I'm
> >not sure it is helping me analyse my initial problem. It seems to be
> >creating problems of its own???
> 
> I just thought of this where inspiration usually takes hold.
> 
> shaddy@*** ~
> $ strace -o /tmp/ls.strace ls
>   22886 [main] ls 4808 C:\software\cygwin\bin\ls.exe: *** fatal
> error - couldn't initialize fd 0 for /dev/tty2
> 
> The OpenProcess() thing, it's actually strace having trouble
> attaching to the ssh tty, right?

strace is a non-Cygwin application.  When you call the application like
this, the inferior process has to initialize the pseudo tty by calling
OpenProcess and in *that* scenario the master process is actually sshd.
It's the same OpenProcess problem in just another shape.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat



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