def load() :
    filename = os.getcwd() + r'\fromto.txt'
    if os.path.isfile(filename) :       
        f = open(filename)
        try :
            lines = f.readlines()
        finally :
            f.close()
            return lines
    else :
        print('请创建fromto.txt.')
        input()
        exit()

def display(_lines) :
    linenum = 1
    s = '序号 源文件 目标文件\n'
    for line in _lines :
        s += str(linenum) + ' ' + line
        linenum += 1
    return s + '\n' + r'请输入序号:'

def work(s, _lines) :
    cmd = r'copy /y ' + _lines[int(s)-1]
    print(cmd)
    os.system(cmd)

if __name__ == "__main__" :

    lines = load()

    while True :
        try :
            s = input(display(lines)).strip()
            if s.lower() == 'exit' :
                break
            if int(s) == 0 :
                lines = load()
                print('已重新加载')
                continue

            work(s, lines)

        except :
            input('--Error--')