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Launching telnet using java program fails with Win 7 OS

 
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I have sample program which launches telnet on Windows XP OS.



In Win 07 we need to manually turned on telnet option. I did it. I able to launch telnet from cmd but above java program fail to launch telnet on Win 7.

What I need to do to launch telnet using Java on Win 7?
 
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Is there an exception / stack trace that can be shared?
 
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Where are you consuming std out and std err and providing std in streams? Read the javadocs for java.lang.Process

Bill
 
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. . . and the classic article which you can find by Googling for Michael Daconta when Runtime.exec() won't.
 
Sham Phadtale
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Thanks all for your quick replies.
I read the classic article. I updated the code as given in article as -



I am getting following out put

Execing cmd.exe /C telnet
ERROR>'telnet' is not recognized as an internal or external command,
ERROR>operable program or batch file.
ExitValue: 1

I can run telnet by opening Start--->cmd---->telnet but not through java program.
What I need to do to run telnet from Java program?
 
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You might consider using the Apache Commons Net package. It lists Telnet in the supported protocol. This examples guide can help you start.

Note that while executing telnet you fork a sub-process from the cmd.exe. Try giving the dir command in your code and check if it works first with the cmd.
 
Sham Phadtale
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dir works from my Java program, it opens command prompt and shows directories.

I will check Apache Commons Net package.
 
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Are you using a 32-bit JVM?

I've tried it on my system as well without Java. I opened CMD from the start menu which will then open a 64-bit CMD window. Telnet works in it. I then opened CMD from Total Commander. Since Total Commander is 32-bit, it launches a 32-bit CMD. Telnet does not work in that. Apparently, on a 64-bit Windows 7 system, telnet only works when launched from a 64-bit application.
 
Sham Phadtale
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Telnet works with CMD but does not work when launch from java program.
 
John Jai
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I guess Rob tells that telnet does not launch from a 32-bit JVM and only on a 64-bit JVM (in case of Win7 i believe). What is the bit version of the JVM that executes your java program and that invokes the cmd.exe?

Which one listed here is that you have - x86 or x64?
 
Sham Phadtale
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OK.. My JVM is 32 bit. I will try by installing 64 bit JVM and check the result.
 
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Sham Phadtale wrote:OK.. My JVM is 32 bit. I will try by installing 64 bit JVM and check the result.



hello, I have the same problem and I would like to know if you already know how to fix it.
Thank you!
 
Campbell Ritchie
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Welcome to the Ranch

You may not get a reply soon since the original poster has not posted anything for over a year.
 
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