import java.io.*;

public class Fork
{
  public static void main( String[] args )
  {
    try
    {
      Runtime env = Runtime.getRuntime();

      Process p = env.exec( "ls -la" );

      // parent does not wait for the child process to terminate
      System.out.println( "I'm the parent. Child process is running..." );

      int rc = p.waitFor();   // parent waits for child to terminate

      if ( rc == 0 ) {
        System.out.println( "...terminated successfully." );
      } else {
        System.out.println( "...terminated with error " + rc );
      }

      BufferedReader stdout =
        new BufferedReader( new InputStreamReader( p.getInputStream() ) );

      BufferedReader stderr =
        new BufferedReader( new InputStreamReader( p.getErrorStream() ) );

      String s;

      System.out.println( "I'm the parent. Child process output:" );
      while ( ( s = stdout.readLine() ) != null ) {
        System.out.println( s );
      }

      System.out.println( "I'm the parent. Child process error output:" );
      while ( ( s = stderr.readLine() ) != null ) {
        System.out.println( s );
      }
    }
    catch ( Exception ex )
    {
      System.err.println( "Exception: " + ex.getMessage() );
    }

  }
}