/dev/ttys* under cygwin problem

/dev/ttys* under cygwin problem

[DEWI - N. Zacharias]

Hi all,

as mentinoned in http://cygwin.com/cygwin-ug-net/using-cygwinenv.html i have set CGWIN to tty .
But there are no tty devices under /dev.

$ echo $CYGWIN
tty

So what is wrong ??

Have a nice time
Norbert

--------------------------------------------------------------------------
Dipl. Phys.
Norbert Zacharias
Wind Measurements & Power Curve Measurements
DEWI GmbH
Ebertstrasse 96
26382 Wilhelmshaven
Germany


Tel.:   +49 4421 4808 876

Fax:    +49 4421 4808 843


Email:  N.Zacharias@dewi.de
Home:   http://www.dewi.de

DEWI GmbH - Deutsches Windenergie-Institut, Wilhelmshaven
Commercial Register No.: Amtsgericht Oldenburg, HRB 130241
Managing Director: Jens Peter Molly
Chairman of the supervisory board: Ministerialrat Dr. Niels Kämpny

P Please consider the environment before printing this email.



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R: /dev/ttys* under cygwin problem

[Marco Atzeri]

--- Mer 22/9/10, DEWI - N. Zacharias  ha scritto:

> 
> Hi all,
> 
> as mentinoned in http://cygwin.com/cygwin-ug-net/using-cygwinenv.html i
> have set CGWIN to tty .
> But there are no tty devices under /dev.
> 
> $ echo $CYGWIN
> tty
> 
> So what is wrong ??
> 
> Have a nice time
> Norbert
> 
> 

the TTY is not really needed anymore, see hand of the paragraph

"It should not be set when using other terminals (i.e., mintty or xterm). "

About the other question, the /dev directory is a bit unusal,
as it is populated by element that are usually not visible with
$ls /dev

see POSIX name on
http://www.cygwin.com/cygwin-ug-net/using-specialnames.htm


try
$ ls -l /dev/tty
crw--w--w- 1 xxx xxxxxxxx 5, 0 2010-09-22 15:21 /dev/tty

$ ls -l /dev/tty1 and so on.


Marco








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AW: [bulk] - R: /dev/ttys* under cygwin problem

[DEWI - N. Zacharias]

Hi,

> Von: Marco Atzeri []
> Gesendet: Mittwoch, 22. September 2010 15:26
> An
> Betreff: [bulk] - R: /dev/ttys* under cygwin problem
>
> --- Mer 22/9/10, DEWI - N. Zacharias  ha scritto:
>
> >
> > Hi all,
> >
> > as mentinoned in http://cygwin.com/cygwin-ug-net/using-cygwinenv.html i
> > have set CGWIN to tty .
> > But there are no tty devices under /dev.
> >
> > $ echo $CYGWIN
> > tty
> >
> > So what is wrong ??
> >
> > Have a nice time
> > Norbert
> >
> >
>
> the TTY is not really needed anymore, see hand of the paragraph
>
> "It should not be set when using other terminals (i.e., mintty or xterm). "
>
> About the other question, the /dev directory is a bit unusal,
> as it is populated by element that are usually not visible with
> $ls /dev
>
> see POSIX name on
> http://www.cygwin.com/cygwin-ug-net/using-specialnames.htm

This link do not work for me.

> try
> $ ls -l /dev/tty
> crw--w--w- 1 xxx xxxxxxxx 5, 0 2010-09-22 15:21 /dev/tty
>
> $ ls -l /dev/tty1 and so on.

Ok :

 ls -al  /dev/ttyS4
crw-rw-rw- 1 n-zacharias Kein 117, 4 22. Sep 17:28 /dev/ttyS4

but

stty -F /dev/ttyS4 ospeed 115200
stty: /dev/ttyS4: Permission denied

Again, whats going wrong

Thanks
Norbert

--------------------------------------------------------------------------
Dipl. Phys.
Norbert Zacharias
Wind Measurements & Power Curve Measurements
DEWI GmbH
Ebertstrasse 96
26382 Wilhelmshaven
Germany


Tel.:   +49 4421 4808 876

Fax:    +49 4421 4808 843


Email:  N.Zacharias@dewi.de
Home:   http://www.dewi.de

DEWI GmbH - Deutsches Windenergie-Institut, Wilhelmshaven
Commercial Register No.: Amtsgericht Oldenburg, HRB 130241
Managing Director: Jens Peter Molly
Chairman of the supervisory board: Ministerialrat Dr. Niels Kämpny

P Please consider the environment before printing this email.



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RE: [bulk] - R: /dev/ttys* under cygwin problem

[Buchbinder, Barry (NIH/NIAID) [E]]

DEWI - N. Zacharias sent the following at Wednesday, September 22, 2010 11:36 AM
>> > as mentinoned in
>> > http://cygwin.com/cygwin-ug-net/using-cygwinenv.html i have set CGWIN to tty .
>> see POSIX name on
>> http://www.cygwin.com/cygwin-ug-net/using-specialnames.htm
>This link do not work for me.

The final "l" was left off.
http://www.cygwin.com/cygwin-ug-net/using-specialnames.html

To go there directly:
http://www.cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-posixdevices

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


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R: AW: [bulk] - R: /dev/ttys* under cygwin problem

[Marco Atzeri]

--- Mer 22/9/10, DEWI - N. Zacharias  ha scritto:

> but
> 
> stty -F /dev/ttyS4 ospeed 115200
> stty: /dev/ttyS4: Permission denied
> 
> Again, whats going wrong
> 
> Thanks
> Norbert

Are you the administrator ?

On my PC it works

$ stty -F /dev/ttyS0 ospeed 64000

$ stty -F /dev/ttyS0 
speed 115200 baud; line = 0;
intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof = <undef>;
swtch = <undef>; susp = <undef>; rprnt = <undef>; werase = <undef>;
lnext = <undef>; flush = <undef>; min = 0; time = 0;
-cread
-brkint -icrnl -imaxbel
-opost -onlcr
-isig -icanon -iexten -echo -echoe -echok -echoctl -echoke


what about http://cygwin.com/problems.html ??

Regards
Marco






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Re: [bulk] - R: /dev/ttys* under cygwin problem

[Daniel Barclay]

Buchbinder, Barry (NIH/NIAID) [E] wrote:
...
> To go there directly:
> http://www.cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-posixdevices

Regarding where that page says:

    These devices cannot be seen with the command ls /dev/ ...

I've wondered about that--why aren't those special files listed in a
directory listing?

(The Cygwin DLL makes those device files appear when they are referred
to by full pathname; why doesn't it also make them appear in the
containing directory's listing?)

Daniel


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Re: [bulk] - R: /dev/ttys* under cygwin problem

[Larry Hall (Cygwin)]

On 9/22/2010 1:29 PM, Daniel Barclay wrote:
> Buchbinder, Barry (NIH/NIAID) [E] wrote:
> ...
>> To go there directly:
>> http://www.cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-posixdevices
>>
>
> Regarding where that page says:
>
> These devices cannot be seen with the command ls /dev/ ...
>
> I've wondered about that--why aren't those special files listed in a
> directory listing?
>
> (The Cygwin DLL makes those device files appear when they are referred
> to by full pathname; why doesn't it also make them appear in the
> containing directory's listing?)

They are implemented in a virtual file system.  It is not necessary that
there be placeholders in the file system for them to work.  But if you
prefer that, you can add them.  This is why the documentation has a link
to the script to create the devices in the file system:

<http://cygwin.com/ml/cygwin/2004-03/txt00028.txt>

-- 
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
216 Dalton Rd.                          (508) 893-9889 - FAX
Holliston, MA 01746

_____________________________________________________________________

A: Yes.
> Q: Are you sure?
>> A: Because it reverses the logical flow of conversation.
>>> Q: Why is top posting annoying in email?

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Re: [bulk] - R: /dev/ttys* under cygwin problem

[Daniel Barclay]

Larry Hall (Cygwin) wrote:
> On 9/22/2010 1:29 PM, Daniel Barclay wrote:
>> Buchbinder, Barry (NIH/NIAID) [E] wrote:
>> ...
>>> To go there directly:
>>> http://www.cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-posixdevices
>>>
>>>
>>
>> Regarding where that page says:
>>
>> These devices cannot be seen with the command ls /dev/ ...
>>
>> I've wondered about that--why aren't those special files listed in a
>> directory listing?
>>
>> (The Cygwin DLL makes those device files appear when they are referred
>> to by full pathname; why doesn't it also make them appear in the
>> containing directory's listing?)
>
> They are implemented in a virtual file system. It is not necessary that
> there be placeholders in the file system for them to work.

But if they were emulated/simulated _consistently_, one could see which
devices were available by simply listing /dev instead of having to
re-find the documentation.

Again, why does Cygwin's (virtual) file system _not_ include those
devices (when listing /dev)?  (Why doesn't it do it more like Linux's
/proc, etc., which gives a consistent view and which tells you what's
available without your having to look elsewhere?)


Actually, is your last sentence above actually true?  Looking at the
device-creation script you pointed me to, I wonder:  How do you (e.g.,
a script) determine which devices of a given type exist (e.g., sda1,
sda2, sda3, ...)?  (Do you have to try to open each possible device and
check whether there's an error?)



> But if you
> prefer that, you can add them. This is why the documentation has a link
> to the script to create the devices in the file system:
>
> <http://cygwin.com/ml/cygwin/2004-03/txt00028.txt>

How do you keep things synchronized?  The script you pointed me to
appears to be over six years old.  I doubt that it matches the code
inside Cygwin 1.7.


Daniel



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Re: [bulk] - R: /dev/ttys* under cygwin problem

[Eric Blake]

On 09/22/2010 03:02 PM, Daniel Barclay wrote:
>> They are implemented in a virtual file system. It is not necessary that
>> there be placeholders in the file system for them to work.
>
> But if they were emulated/simulated _consistently_, one could see which
> devices were available by simply listing /dev instead of having to
> re-find the documentation.

http://cygwin.com/acronyms/#PTC

> Again, why does Cygwin's (virtual) file system _not_ include those
> devices (when listing /dev)? (Why doesn't it do it more like Linux's
> /proc, etc., which gives a consistent view and which tells you what's
> available without your having to look elsewhere?)

Because no one has taken the time to write the code.  Also, unlike 
Linux, where the kernel knows what devices are present, a cygwin 
implementation would have to make a lot of syscalls querying whether 
each potential device is available.  One other drawback - cygwin would 
like things like /dev/stdin to work as a symlink to /proc/self/0, but 
that is a normal symlink in today's cygwin implementation, and not an 
entry in the virtual file system.  Therefore, part of the implementation 
battle is figuring out how to merge an existing directory containing 
user-added symlinks or device names, in parallel with the virtual 
devices supported by the virtual FS magic compiled into cygwin.

> Actually, is your last sentence above actually true? Looking at the
> device-creation script you pointed me to, I wonder: How do you (e.g.,
> a script) determine which devices of a given type exist (e.g., sda1,
> sda2, sda3, ...)? (Do you have to try to open each possible device and
> check whether there's an error?)

The script creates every known name, whether or not it actually exists 
as a device at the current moment, which is in itself a bit misleading. 
  But it has to, because of devices which can be added and removed on 
the fly, whereas the script creating the placeholder files is only run once.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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Re: [bulk] - R: /dev/ttys* under cygwin problem

[Daniel Barclay]

Eric Blake wrote:
> On 09/22/2010 03:02 PM, Daniel Barclay wrote:
...
>> Again, why does Cygwin's (virtual) file system _not_ include those
>> devices (when listing /dev)? (Why doesn't it do it more like Linux's
>> /proc, etc., which gives a consistent view and which tells you what's
>> available without your having to look elsewhere?)
>
> ...Also, unlike Linux,
> where the kernel knows what devices are present, a cygwin implementation
> would have to make a lot of syscalls querying whether each potential
> device is available.

Oh--so Cygwin would have to query Windows for the current set of
devices (which can change over time (right?)) each time the /dev
directory was listed (since it doesn't maintain the net device list
itself as a kernel would)?)?

> One other drawback - ... part of the implementation battle is
> figuring out how to merge an existing directory containing user-added
> symlinks or device names, in parallel with the virtual devices supported
> by the virtual FS magic compiled into cygwin.

Okay, yeah, I see how that could be tricky.

Wait a minute--doesn't Cygwin have to do that anyway?  If the user
adds a symlink or device with the same name as that of a virtual
device provided by Cygwin, and then refers to that pathname
(/dev/something), haven't the Cygwin designers already had to decide
what happens (whether the user gets the virtual device or, say,
gets the target of the symlink)?  If so, does listing the /dev
directory really add some additional consideration?

>
>> Actually, is your last sentence above actually true? Looking at the
>> device-creation script you pointed me to, I wonder: How do you (e.g.,
>> a script) determine which devices of a given type exist (e.g., sda1,
>> sda2, sda3, ...)? (Do you have to try to open each possible device and
>> check whether there's an error?)
>
> The script creates every known name, whether or not it actually exists
> as a device at the current moment, which is in itself a bit misleading.
> But it has to, because of devices which can be added and removed on the
> fly, whereas the script creating the placeholder files is only run once.

Yes, I got that part.  What I was wondering was what would be the
recommended way to determine which devices really existed.  Would it
be trying to open the device and checking for some "no such device"
error?


Daniel


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