1.parser.cpp and  parse.h
  replace the pushpath() and make_info() with the function command() and input()
use to analyze command;
  scan(): include the case of '>' and ">>";
2.exe_utils.cpp and exe_utils.h
  add the function set_apend() to sign the option of apend;
  add the function is_apend() to judge the input has the apend command;