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DEBUG over terminal emulation

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Regular Visitor

DEBUG over terminal emulation




I have the following setup to connect to our customer's VMS systems.


(A) My Windows system XP -------------------------------------> Windows 2003 server via Remote Desktop  (B)


(B) --------> VMS authentication server 1 ------> Authentication Server 2 ------------> VMS system hosting application (E).


I connect from (B) to (E) using reflection (SSH).



I want to debug an application with screens developed in SMG.

I have been reading the debugger manual which describes how to run the application in one termial and redirect the debug session to another. 

However, the terminals being discussed are either

a. hardwired to the system


b. connected via LAT.


In my case, I cannot from terminal 1 (where I want to run the program) do ALLOCATE TTD2: because I get tis message: SYSTEM-W-DEVALLOC, device already allocated to another user. 


Please suggest where I am going wrong. Thanks!

John Gillings
Honored Contributor

Re: DEBUG over terminal emulation

It sounds like the instructions assume a physical terminal which can be allocated without privilege.


If you're using a terminal emulator the terminal device doesn't exist until you connect, so there will always be a process owning the target terminal window. To get around this you will need SHARE privilege in the process running DEBUG.


From the terminal window you want to display DEBUG on do this:



Terminal: _FTA26:     Device_Type: VT102         Owner: JG0
                                              Username: GILLINGS_J


$ WAIT 10


You now know the terminal name, and the process which owns it will sleep for 10 hours to keep it out of the way. In my case the terminal is FTA26:


Now from the terminal window you want to run the program in, do this:





$ RUN/DEBUG your-program


You should see a debug banner and DBG> prompt on the other terminal window.


Once you've finished with DEBUG hit ^Y to wake up the sleeping process.


This will work for any terminal type or connection mechanism. BUT you need privilege.


If this doesn't work, please post a transcript of the exact steps you're performing and the exact and complete output.

A crucible of informative mistakes
Ph Vouters
Valued Contributor

Re: DEBUG over terminal emulation

Dear SSengupta,



If the SYS$REM_NODE job logical on node E points to your Windows XP node, why not using the DCL code at http://vouters.dyndns.org/tima/All-OS-Setting_a_remote_VMS_display.html ? Only ensure that the DBG$DECW$DISPLAY logical is not set to " " in your login.com. This way you will be able to execute the graphical version of the debugger with a remote display onto your Windows XP PC. Also the SMG routines display from your program will not interfere with the debugger's display. With the graphical version of the debugger, you will not need to define DBG$INPUT and DBG$OUTPUT.


The other solution I know is the one posted by John Gillings. This will cause you to work with two different terminals.


Yours truly,


Ph Vouters
Valued Contributor

Re: DEBUG over terminal emulation

As you connect from your Windows XP to your Windows 2003 server using Remote Desktop and then from your Windows 2003 server to OpenVMS using SSH, the SYS$REM_NODE ought to point to your Windows 2003 server. If you install an X server such as Xming onto the Windows 2003 server, then you likely ought to be able to run the graphical VMS debugger onto your Remote Desktop session. The remaining of my explanations in my previous post remain valid.


Sorry, I missed this in your explanations.


Regular Visitor

Re: DEBUG over terminal emulation

Hello John Gillins

Thanks for the response. To make your solution work, I had to do in Terminal FTA26: the following as well:



This enabled me to redirect debugging INPUT and OUTPUT to FTA26:. Meanwhie the screen from the program was getting sent to the original terminal.


Apologies for not responsing earlier, I was down with a viral infection. Your help is appreciated. Thank you!

Regular Visitor

Re: DEBUG over terminal emulation

Hello Vouters

Thanks for your response, but other than SSH, no X tools have been installed. No NetBeans either. So there is no way I could redirect the X output. Cheers!