| re: Flakey Results from Runtime.exec() On Windows 2000
Additional info at bottom:
Hal Vaughan wrote:
[color=blue]
> I've been using Runtime.exec() like this:
>
> Runtime rt = Runtime.getRuntime();
> try {Process p = rt.exec("MyCommand.bat");} catch (Exception e) {do stuff}
>
> When I start my Java classes, I start them with a batch file that changes
> to
> my apps home directory. I've tried exec() with a full pathname (which
> seems to have problems on Windows if it has spaces in it, but I'm not sure
> if that's really the problem), with just the simple short batch file name,
> and with ".\MyCommand.bat".
>
> I have one class that is VERY simple that has managed to do this okay, but
> I've tried this in a number of variations. I even took the simple class
> and changed ONLY the batch file name and classname so it would run another
> batch file in the same dir. It wouldn't. (Yes, the file had read and
> exec permissions set.)
>
> All of these commands worked perfectly on Linux (and I am definately
> changing the pathnames to use the correct file separator). So I have:
>
> 1) exec(command) that works on Linux, but not on Windows, even with
> pathnames corrected,
> 2) A class that runs a batch file, but will not run others in the same
> directory, even if they have the correct permission bits set.
>
> What kind of factors can effect this? I wouldn't think the length of the
> filename should matter. I can't figure out what else would be the
> difference.
>
> I can post the code of all examples, but it's basically the same as above.
> (I've used a String I defined earlier in some cases and also used a string
> with quotation marks at the start and end, also.) I just can't figure out
> why it works sometimes and not others.
>
> Any ideas?
>
> Thanks!
>
> Hal[/color]
I tried reading the error stream from the process I created -- and got
nothing. So I changed that to the intput stream (which confused me at
first, because I thought I should be reading the output stream). I finally
got it working with the code below. Basically, I have an endless loop in
the thread that reads the output from the process. I added in a 1/100 of a
second delay so it didn't freeze up the system. This leaves a few
questions:
1) How can I tell when this is done and kill the thread? I know I can use
Process.waitFor(), but that locks up, instead of checking if it is done.
(The best I can think of is passing the process to yet another thread that
does nothing but Process.waitFor(); and, after that, Process.destroy();)
2) Is there any way to redirect the output of a Windows program without
sending it to a file so I don't have to read the output to make sure it
runs?
Thanks for any thoughts.
Hal
Thread Runner = new Thread() {
public void run() {
byte[] bOut;
int iLen;
Runtime rt = Runtime.getRuntime();
Process p = null;
String sLine = "MyProgram.bat\n";
try {
p = rt.exec(sLine);
InputStream is = p.getInputStream();
while (true) {
iLen = is.available();
bOut = new byte[iLen];
is.read(bOut);
try {Thread.sleep(10);} catch (Exception e) {}
}
} catch (Exception e)
{System.out.println("Cannot Run Command: " + sLine + ", Error: " + e);}
}
};
Runner.start();
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