我有一个python脚本更新外部excel链接，然后复制到一个新的目录，但我想前缀它的日期，因为它会发生几次，一个月。目前，脚本只复制到同一目录的文件，并改变名称。

import os
import shutil
import fnmatch
from datetime import datetime

prefix = datetime.today().strftime('%y%m%d')
dir_src = ("D:\\Users\\cdoyle\\Desktop\\TGround\\")
dir_dst = ("D:\\Users\\cdoyle\\Desktop\\TGround\\GUID\\")
filename = ("All Facilities - GUID Duplicates Tracking.xlsx")
outputname = os.path.join(prefix + "-" + filename)
srcfile = ("D:\\Users\\cdoyle\\Desktop\\TGround\\All Facilities - GUID Duplicates Tracking.xlsx")
desfile = ("D:\\Users\\cdoyle\\Desktop\\TGround\\GUID\\All Facilities - GUID Duplicates Tracking.xlsx")

if os.path.exists(srcfile):
    shutil.copy( dir_src + filename, dir_dst)
    print(filename)

if os.path.exists(desfile):
    os.rename("D:\\Users\\cdoyle\\Desktop\\TGround\\GUID\\All Facilities - GUID Duplicates Tracking.xlsx", outputname)
    print (outputname)