calling a perl script from java program

[Ishita Saha]

Hi,

I need to execute a perl script from a java program, I got some stuff on google:

 
import java.io.*;

public class RunCommand {

	public static void main(String args[]) {

		Process process;

		try
		{
		process = Runtime.getRuntime().exec("cmd.exe /c:/perl/bin perl.exe basic.pl");
		process.waitFor();
		if(process.exitValue() == 0)
		{
		System.out.println("Command Successful");
		try {
		BufferedReader in = new BufferedReader(new InputStreamReader(process.getInputStream()));
		String line = null;
		while ((line = in.readLine()) != null) {
		System.out.println(line);
		}
		} catch (IOException e) {
		e.printStackTrace();
		}
		}
		else
		{
		System.out.println("Command Failure");
		}
		}
		catch(Exception e)
		{
		System.out.println("Exception: "+ e.toString());
		}
		}
}

It gives me the output as: Command Successful
but I need to see the output which should be: "I have a no" (which is there in basic.pl)

also I tried running another script - which should create a txt file ( that is not happening either)

any help is appreciated.
Thanks!

[Campbell Ritchie]

You need to "drain" both Streams associated with the Process, not only the input stream. The ProcessBuilder class makes that a little easier in Java5, but you can get all sorts of problems with Processes if you don't start a parallel thread. For details look for Michael Daconta's classic article "When Runtime.exec() won't"

[William Brogden]

When running a Process, you should provide for consuming both std out and std err streams. Your code waits for the Process to end, but does not consume the output while the process is running. This is a recipe for disaster since the process may hang trying to output to std out or std err.

Bill