* com1 access denied - win xp @ 2004-05-20 16:49 Michael Wood 2004-05-20 17:45 ` Igor Pechtchanski ` (2 more replies) 0 siblings, 3 replies; 7+ messages in thread From: Michael Wood @ 2004-05-20 16:49 UTC (permalink / raw) To: cygwin Hi-ya, I get an "Access is denied" error message when attempting to create a serial port connection through Cygwin, running on Win XP. In cygwin, when I execute: ls -l COM1 I get the following: -rw-r--r-- 1 mwood mkgroup- 0 Jan 1 1970 COM1 However, when I execute: chmod a+rw COM1 the command exits normally (no error message), but the permissions on COM1 stay the same. Furthermore, I do not particularly understand why if I am the owner of COM1 (as illustrated by the 'ls -l'), why I would get a permission error. I have successfully created and used a connection on the serial port on the same machine through a VMWare session running a Linux Red Hat image. I used a very similar procedure above, in that I simply changed the permissions on "/dev/ttyS0" to grant all users read and write permissions to the serial port. Help would be greatly appreciated. - Mike -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/ ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: com1 access denied - win xp 2004-05-20 16:49 com1 access denied - win xp Michael Wood @ 2004-05-20 17:45 ` Igor Pechtchanski 2004-05-21 0:10 ` Igor Pechtchanski 2004-05-20 18:27 ` Dave Korn 2004-05-20 20:44 ` Brian Ford 2 siblings, 1 reply; 7+ messages in thread From: Igor Pechtchanski @ 2004-05-20 17:45 UTC (permalink / raw) To: Michael Wood; +Cc: cygwin On Thu, 20 May 2004, Michael Wood wrote: > [snip] > I have successfully created and used a connection on the serial port on > the same machine through a VMWare session running a Linux Red Hat image. > I used a very similar procedure above, in that I simply changed the > permissions on "/dev/ttyS0" to grant all users read and write > permissions to the serial port. > > Help would be greatly appreciated. > - Mike Mike, Given that you used "/dev/ttyS0" on Linux, why not try using the same on Cygwin? Igor -- http://cs.nyu.edu/~pechtcha/ |\ _,,,---,,_ pechtcha@cs.nyu.edu ZZZzz /,`.-'`' -. ;-;;,_ igor@watson.ibm.com |,4- ) )-,_. ,\ ( `'-' Igor Pechtchanski, Ph.D. '---''(_/--' `-'\_) fL a.k.a JaguaR-R-R-r-r-r-.-.-. Meow! "I have since come to realize that being between your mentor and his route to the bathroom is a major career booster." -- Patrick Naughton ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: com1 access denied - win xp 2004-05-20 17:45 ` Igor Pechtchanski @ 2004-05-21 0:10 ` Igor Pechtchanski 0 siblings, 0 replies; 7+ messages in thread From: Igor Pechtchanski @ 2004-05-21 0:10 UTC (permalink / raw) To: Michael Wood; +Cc: cygwin On Thu, 20 May 2004, Michael Wood wrote: > [snip] > I have successfully created and used a connection on the serial port on > the same machine through a VMWare session running a Linux Red Hat image. > I used a very similar procedure above, in that I simply changed the > permissions on "/dev/ttyS0" to grant all users read and write > permissions to the serial port. > > Help would be greatly appreciated. > - Mike Mike, Given that you used "/dev/ttyS0" on Linux, why not try using the same on Cygwin? Igor -- http://cs.nyu.edu/~pechtcha/ |\ _,,,---,,_ pechtcha@cs.nyu.edu ZZZzz /,`.-'`' -. ;-;;,_ igor@watson.ibm.com |,4- ) )-,_. ,\ ( `'-' Igor Pechtchanski, Ph.D. '---''(_/--' `-'\_) fL a.k.a JaguaR-R-R-r-r-r-.-.-. Meow! "I have since come to realize that being between your mentor and his route to the bathroom is a major career booster." -- Patrick Naughton -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/ ^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: com1 access denied - win xp 2004-05-20 16:49 com1 access denied - win xp Michael Wood 2004-05-20 17:45 ` Igor Pechtchanski @ 2004-05-20 18:27 ` Dave Korn 2004-05-24 20:30 ` Michael Wood 2004-05-20 20:44 ` Brian Ford 2 siblings, 1 reply; 7+ messages in thread From: Dave Korn @ 2004-05-20 18:27 UTC (permalink / raw) To: cygwin > -----Original Message----- > From: cygwin-owner On Behalf Of Michael Wood > Sent: 20 May 2004 17:23 > Hi-ya, > > I get an "Access is denied" error message when attempting to create a > serial port connection through Cygwin, running on Win XP. > > In cygwin, when I execute: > ls -l COM1 > > I get the following: > -rw-r--r-- 1 mwood mkgroup- 0 Jan 1 1970 COM1 > > However, when I execute: > chmod a+rw COM1 > > the command exits normally (no error message), but the permissions on > COM1 stay the same. Furthermore, I do not particularly > understand why if > I am the owner of COM1 (as illustrated by the 'ls -l'), why I > would get > a permission error. > > I have successfully created and used a connection on the > serial port on > the same machine through a VMWare session running a Linux Red > Hat image. > I used a very similar procedure above, in that I simply changed the > permissions on "/dev/ttyS0" to grant all users read and write > permissions to the serial port. > > Help would be greatly appreciated. > > - Mike #1. Why not use /dev/ttyS0 again? Cygwin is a posix compatible layer and /dev/ttyS0 should work pretty much the same. BTW, which directory are you in when you do those commands on COM1? Did you "cd /dev" or do you expect it to just work anywhere, and if so, why? #2. 'doze has some pretty funny ideas about files having the same name as dos-devices (COMx:, PRN:, LPTx: etc). It doesn't like it at all. Presumably somewhere between cygwin and 'doze a bit of confusion is creeping in. #3. I notice that if you're in /dev and you do "ls -la com1", you get the right answer. But remember, under Posix, capitalisation matters, so "com1" and "COM1" are two different files. Under 'doze, unfortunately, it doesn't. So probably Cygwin knows that /dev/com1 is the serial port, thinks that /dev/COM1 is something different because the case doesn't match, assumes it's an ordinary file and passes the name through to the underlying 'doze file-handling calls, which disagree with cygwin and think that it IS a serial port, and then everybody gets confused. #4. When I do "ls -la COM1", I just get: dk@mace /> ls -la COM1 ---------- 0 ???????? ???????? 0 Jan 1 1970 COM1 no matter what directory I'm in. Bizarre. When I'm do "ls -la /dev/com1", I get the proper answer: dk@mace /> ls -la /dev/com1 crw-rw-rw- 1 dk Domain U 117, 1 May 20 19:05 /dev/com1 but capitalizing it never works, not even in the /dev directory. dk@mace /> ls -la /dev/COM1 ---------- 0 ???????? ???????? 0 Jan 1 1970 /dev/COM1 #5. Anyway, the answer to your problem is that you were using the wrong filename. The solution is to use the correct filename; either /dev/com1 or /dev/ttyS0. And as to why there's a messed up COM1 in there, that's a little bugette you've stumbled across. cheers, DaveK -- Can't think of a witty .sigline today.... ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: com1 access denied - win xp 2004-05-20 18:27 ` Dave Korn @ 2004-05-24 20:30 ` Michael Wood 0 siblings, 0 replies; 7+ messages in thread From: Michael Wood @ 2004-05-24 20:30 UTC (permalink / raw) To: cygwin Thanks for your speedy replies (and I apologize for not getting back to you until now). I have determined simply from trying various combinations of things, that "COM1" is a name that is created within cygwin when a device is connected to the serial port and powered-on. The name "/dev/com1" always exists, and appears to be synonymous with "/dev/ttyS0", however neither can be used in place of "COM1" in the Cygwin shell to refer to the serial port. Both of these names also always return the correct "crw-rw-rw-" permissions for a "ls -l", where as a "ls -l COM1" results in "-rw-r--r--" when a device is plugged into the serial port and powered-on, otherwise the call simply hangs. In the end, the important part is that the permissions above likely had nothing to do with my "Access Denied" error. This was caused by my Linux VMWare session running at the same time as my Cygwin shell. If I let the Linux VMWare session boot first and grab the serial port, then Cygwin couldn't see it (apparently) and vice versa. As soon as I shutdown the VMWare session, I could then gain access to the serial port using "COM1" through the Cygwin shell. Thanks again for your replies guys. - Mike Dave Korn wrote: >>-----Original Message----- >>From: cygwin-owner On Behalf Of Michael Wood >>Sent: 20 May 2004 17:23 > > >>Hi-ya, >> >>I get an "Access is denied" error message when attempting to create a >>serial port connection through Cygwin, running on Win XP. >> >>In cygwin, when I execute: >> ls -l COM1 >> >>I get the following: >> -rw-r--r-- 1 mwood mkgroup- 0 Jan 1 1970 COM1 >> >>However, when I execute: >> chmod a+rw COM1 >> >>the command exits normally (no error message), but the permissions on >>COM1 stay the same. Furthermore, I do not particularly >>understand why if >>I am the owner of COM1 (as illustrated by the 'ls -l'), why I >>would get >>a permission error. >> >>I have successfully created and used a connection on the >>serial port on >>the same machine through a VMWare session running a Linux Red >>Hat image. >>I used a very similar procedure above, in that I simply changed the >>permissions on "/dev/ttyS0" to grant all users read and write >>permissions to the serial port. >> >>Help would be greatly appreciated. >> >>- Mike > > > > #1. Why not use /dev/ttyS0 again? Cygwin is a posix compatible layer and > /dev/ttyS0 should work pretty much the same. BTW, which directory are you > in when you do those commands on COM1? Did you "cd /dev" or do you expect > it to just work anywhere, and if so, why? > > #2. 'doze has some pretty funny ideas about files having the same name as > dos-devices (COMx:, PRN:, LPTx: etc). It doesn't like it at all. > Presumably somewhere between cygwin and 'doze a bit of confusion is creeping > in. > > #3. I notice that if you're in /dev and you do "ls -la com1", you get the > right answer. But remember, under Posix, capitalisation matters, so "com1" > and "COM1" are two different files. Under 'doze, unfortunately, it doesn't. > So probably Cygwin knows that /dev/com1 is the serial port, thinks that > /dev/COM1 is something different because the case doesn't match, assumes > it's an ordinary file and passes the name through to the underlying 'doze > file-handling calls, which disagree with cygwin and think that it IS a > serial port, and then everybody gets confused. > > #4. When I do "ls -la COM1", I just get: > > dk@mace /> ls -la COM1 > ---------- 0 ???????? ???????? 0 Jan 1 1970 COM1 > > no matter what directory I'm in. Bizarre. When I'm do "ls -la /dev/com1", > I get the proper answer: > > dk@mace /> ls -la /dev/com1 > crw-rw-rw- 1 dk Domain U 117, 1 May 20 19:05 /dev/com1 > > but capitalizing it never works, not even in the /dev directory. > > dk@mace /> ls -la /dev/COM1 > ---------- 0 ???????? ???????? 0 Jan 1 1970 /dev/COM1 > > #5. Anyway, the answer to your problem is that you were using the wrong > filename. The solution is to use the correct filename; either /dev/com1 or > /dev/ttyS0. And as to why there's a messed up COM1 in there, that's a > little bugette you've stumbled across. > > cheers, > DaveK -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/ ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: com1 access denied - win xp 2004-05-20 16:49 com1 access denied - win xp Michael Wood 2004-05-20 17:45 ` Igor Pechtchanski 2004-05-20 18:27 ` Dave Korn @ 2004-05-20 20:44 ` Brian Ford 2004-05-21 1:30 ` Brian Ford 2 siblings, 1 reply; 7+ messages in thread From: Brian Ford @ 2004-05-20 20:44 UTC (permalink / raw) To: Michael Wood; +Cc: cygwin On Thu, 20 May 2004, Michael Wood wrote: > I get an "Access is denied" error message when attempting to create a > serial port connection through Cygwin, running on Win XP. > > In cygwin, when I execute: > ls -l COM1 > > I get the following: > -rw-r--r-- 1 mwood mkgroup- 0 Jan 1 1970 COM1 Not related, but note the mkgroup- in the group field. That means your group is not part of /etc/group. Please see "man mkgroup" to fix this. I get the following with the latest snapshot: -rwxrwxrwx 1 Administ SYSTEM 0 Dec 31 1969 COM1* which may or may not make more sense to you. > However, when I execute: > chmod a+rw COM1 > > the command exits normally (no error message), but the permissions on > COM1 stay the same. AFAIK, you can't change the POSIX derived permissions of DOS devices. > Furthermore, I do not particularly understand why if I am the owner of > COM1 (as illustrated by the 'ls -l'), why I would get a permission > error. That may depend on the version of Cygwin you are using. Please see: http://cygwin.com/problems.html for the required information in a problem report. > I have successfully created and used a connection on the serial port on > the same machine through a VMWare session running a Linux Red Hat image. > I used a very similar procedure above, in that I simply changed the > permissions on "/dev/ttyS0" to grant all users read and write > permissions to the serial port. Does this help? http://cygwin.com/cygwin-ug-net/using-specialnames.html#AEN806 Don't use a DOS device if you want POSIX behavior. -- Brian Ford Senior Realtime Software Engineer VITAL - Visual Simulation Systems FlightSafety International the best safety device in any aircraft is a well-trained pilot... ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: com1 access denied - win xp 2004-05-20 20:44 ` Brian Ford @ 2004-05-21 1:30 ` Brian Ford 0 siblings, 0 replies; 7+ messages in thread From: Brian Ford @ 2004-05-21 1:30 UTC (permalink / raw) To: Michael Wood; +Cc: cygwin On Thu, 20 May 2004, Michael Wood wrote: > I get an "Access is denied" error message when attempting to create a > serial port connection through Cygwin, running on Win XP. > > In cygwin, when I execute: > ls -l COM1 > > I get the following: > -rw-r--r-- 1 mwood mkgroup- 0 Jan 1 1970 COM1 Not related, but note the mkgroup- in the group field. That means your group is not part of /etc/group. Please see "man mkgroup" to fix this. I get the following with the latest snapshot: -rwxrwxrwx 1 Administ SYSTEM 0 Dec 31 1969 COM1* which may or may not make more sense to you. > However, when I execute: > chmod a+rw COM1 > > the command exits normally (no error message), but the permissions on > COM1 stay the same. AFAIK, you can't change the POSIX derived permissions of DOS devices. > Furthermore, I do not particularly understand why if I am the owner of > COM1 (as illustrated by the 'ls -l'), why I would get a permission > error. That may depend on the version of Cygwin you are using. Please see: http://cygwin.com/problems.html for the required information in a problem report. > I have successfully created and used a connection on the serial port on > the same machine through a VMWare session running a Linux Red Hat image. > I used a very similar procedure above, in that I simply changed the > permissions on "/dev/ttyS0" to grant all users read and write > permissions to the serial port. Does this help? http://cygwin.com/cygwin-ug-net/using-specialnames.html#AEN806 Don't use a DOS device if you want POSIX behavior. -- Brian Ford Senior Realtime Software Engineer VITAL - Visual Simulation Systems FlightSafety International the best safety device in any aircraft is a well-trained pilot... -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/ ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2004-05-24 16:34 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2004-05-20 16:49 com1 access denied - win xp Michael Wood 2004-05-20 17:45 ` Igor Pechtchanski 2004-05-21 0:10 ` Igor Pechtchanski 2004-05-20 18:27 ` Dave Korn 2004-05-24 20:30 ` Michael Wood 2004-05-20 20:44 ` Brian Ford 2004-05-21 1:30 ` Brian Ford
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