Operational Systems & Java

Currently I m running two operating systems on one machine, Windows 2000 and

Windows ME. 

Windows ME runs on default, Windows 2000 is on D drive and ME is on C drive. I

tried to add the JDK directory to the classpath but there isn t a autoexec.bat on the D

directory, but there is one for C. 

Should I just create a autoexec.bat for D?

Answer:  Go to Settings/Control Panel/System/Advanced/Environment Variables...

and 

edit your CLASSPATH variable if exists or add a new one.

I need to be able to run a shell script from java, by doing a host call to unix. I am

currently trying  Runtime.exec  to do this. It says it runs it, but doesn t actually

successfully complete the command (which is a file delete).

I need to be able to run a shell script from java, by doing a host call to unix. I am

currently trying  Runtime.exec  to do this. It says it runs it, but doesn t actually

successfully complete the command (which is a file delete).

A few questions I have about this:

1. Can I trace it or something to see why it isn t working?

2. How can I get the  return code  from the shell script?

3. Will the java procedure wait for the shell script to execute, or does

it run a seperate thread concurrently?

Answer:  > 1. Can I trace it or something to see why it isn t working?

Runtime.exec() returns a Process object that you can get information from.

If the script is written with sh or some derivate thereof you can do  set  x  in the script

to trace its behaviour. For other scripting languages there is likely a similar

mechanism. To see the trace in your Java program, read from the error or output

streams of the process (Process.getErrorStream() or Process.getOutputStream()).

It s possible that the script is already printing a message to its error stream that you

aren t seeing, indicating why it isn t working.

Answer: > 2. How can I get the  return code  from the shell script?

Call Process.exitValue().

Answer: > 3. Will the java procedure wait for the shell script to execute, or does it run

a seperate thread concurrently?

The program runs concurrently in a separate *process*, not a thread within the JVM.

To wait for the process to finish, call Process.waitFor().

 Are not initializable classes and methods like System.out.println() and

Math.random() "synchronized" ?

Answer: I think they are synchronized. Simple observation: did you ever see once

that printout was broken into two pices by another printouts? I mean for example if

you do: 

In 1st thread: System.out.println("1234567890"); 

And in 2nd thread: System.out.println("something else here");

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