GNU Readline函数库
readline --- 读取字符串
readline_add_history --- 在记录中增加一行
readline_clear_history --- 清除记录
readline_completion_function --- 登记一个结束函数
readline_info --- 取得或设定readline各个内部的值
readline_list_history --- 列出记录
readline_read_history --- 读取记录
readline_write_history --- 写入记录