import java.io.*;

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

//      Process p = env.exec( "vi xyz.txt" );
//      Process p = env.exec( "lsxyfew -l" );
      Process p = env.exec( "ls -e" );

      // parent does not wait for child
      System.out.println( "PARENT: child process is running..." );

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

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

      int rc = p.waitFor();   // block and wait for child to terminate

      if ( rc == 0 ) {
        System.out.println( "...child terminated normally" );
      } else {
        System.err.println( "...child terminated abnormally with error " + rc );
      }

      String s;
      System.out.println( "PARENT: child process output:" );
      while ( ( s = stdin.readLine() ) != null )
      {
        System.out.println( s );
      }

      System.out.println( "PARENT: child process error output:" );
      while ( ( s = stderr.readLine() ) != null )
      {
        System.out.println( s );
      }
    }
    catch ( Exception ex )
    {
      System.err.println( "Exception: " + ex.getMessage() );
    }
  }
}