lucene merging index

public static void main (String ... args) throws Exception{
		
		IndexWriter iw_temp = new IndexWriter("i.temp",new StandardAnalyzer());
		IndexWriter iw = new IndexWriter("i",new StandardAnalyzer());
		
		for(int i = 0;  i < 200 ; i++){
			p("Adding new 1000 document to temp index ...");
			addDocs(iw_temp, 1000);
			p("adding to temp done.");
			
			p("merging ... ");
			iw.addIndexes(new Directory[] {iw_temp.getDirectory()});
			p("merging done.");
			
			p("deleting temp index ...");
			Runtime.getRuntime().exec("rm -rf i.temp");
			iw_temp =  new IndexWriter("i.temp",new StandardAnalyzer());
			p("deleting temp index done.");
		}
	}