How to capture text os output

[brinker]

Hello,

I have been working on a problem that involves executing a command line statement in java such as gcc -c fileName. I want to capture the screen output (ie. errors, success) which generally appears as text such as :

compile successful

or

Error in line 23

Since these commands do not work in a window, but appear as lines in the OS display, is there a way to capture them. The following syntax does not work:

----------------------------------------------------------------------------------
Process extProcess=rt.exec(cmd);
extProcess.waitFor();

// receive the output of external program
InputStream extInput = extProcess.getInputStream();
int bytesAvailable = extInput.available();
if (bytesAvailable > 0)
{
byte[] extInputData = new byte[bytesAvailable];
extInput.read(extInputData);
System.out.println(new String(extInputData));
for (int i=0;i<bytesAvailable;i++) {
s+=(char)extInputData;
}
JOptionPane.showMessageDialog(null,s ,&quot;testing it&quot;,JOptionPane.INFORMATION_MESSAGE);
outputS=s;
System.out.println(&quot;\nFile Compiled Successfully&quot;
// System.exit(0);
}

------------------------------------------------------------------------

probably because jave sees no bytes available. I have tried creating a command shell using '/c', but this does not help.

 

[LittleWing]

have you tried redirecting the output from the process into a flat file and then read that into your program???

gcc -c filename > output.txt

 

[brinker]

the command :

gcc -c filename>output.txt creates an output file, but it does not capture the screen output (ie. error in line 23, etc).

Brinker

 

[meadandale]

Has it occurred to you that the process output that you are trying to capture is probably on stderr and not stdout?

Instead of using getInputStream, use getErrorStream.

 

[meadandale]

Also, you need to read the output before you block waiting for the process to finish.

See the following URL for an example:

http://www.recallwd.com/books/web-java/chapter_14.htm#TheRuntimeandProcessClasses

 

[brinker]

Thanks everyone for your help.

The problem was with the standard error stream and not with stdout. It is solved. Yippie!