Re: Runtime.exec on Win98: stdin, stdout with long DOS command line?

Bernard wrote: 
Hi all Java Gurus

I can't get Runtime.exec() to work with DOS commands longer than 127
characters (the command.com limit) under Win98 2nd edition.

I use a workaround, start.exe to execute my DOS command. This executes
command lines successfully that are longer than 127 characters.

However, with start.exe, stdin and stdout of my executed command do
not appear to be accessible at all from the Java Process object.

Whatever I write to Process.getOutputStream() gets ignored, typically
with the effect of the DOS program hanging while it waits for input.

If I don't need to write to Process.getOutputStream(), then still
whatever I read from Process.getInputStream() is empty.

This is all Win9x specific, because on NT, Win2000 and XP systems,
there is no such command line length limitation, and therefore there
is no need for the start.exe workaround.

I use separate threads for reading stdin and stderr much like as
documented at
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps_p.html
so I am not a beginner in the use of Runtime.exec().

It appears to me that my issue is not yet documented anywhere on the
web. It would be nice to have a simple solution. As long as there is
none, my recommendation would be to avoid Runtime.exec on Win9*
platforms wherever stdin, stdout and stderr must be used, because it
would be dangerous to ignore the 127 character command line length
limit of command.com.

Any suggestions are highly appreciated.


1) You could try writing out your command to a temporary BAT file, and then simply execute the BAT file via Runtime.exec(). I think that the streams will be preserved in that case, but you may need to experiment.

2) Have you tried using Runtime.exec(String[]) (instead of Runtime.exec(String))?

HTH,
Ray

--
XML is the programmer's duct tape.
.

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