сat my.file | java -jar my.jar

         try  {
            BufferedReader in =  new  BufferedReader( new  InputStreamReader(System.in));
            StringBuffer sb =  new  StringBuffer();
             int  myChar;
             while  ((myChar = in.read())!=- 1 ) {
                sb.append(( char )(myChar));
            }    
            FileOutputStream fos =  new  FileOutputStream("test.file");
            String str = "\n=== Cut here ===\n";
            String strWrite = str+sb.toString()+str;
            fos.write(strWrite.getBytes());
            fos.close();
        }  catch  (FileNotFoundException ex) {
            ex.printStackTrace();
        }  catch  (IOException ex) {
            ex.printStackTrace();
        }
    }