python定时下载FTP指定文件

#coding=utf-8
#!/usr/bin/env python
from ftplib import FTP
import datetime
import re
def ftpconnect():
ftp_server = 'IP'
username = '账号'
password = '密码'
ftp = FTP()
ftp.connect(ftp_server,21)
ftp.login(username,password)
print ftp.getwelcome()
return ftp

def downloadfile():
#格式化取到昨天的日期
d = (datetime.datetime.now() - datetime.timedelta(days=1)).strftime('%Y%m%d')
remotepath = '/bssdata1/interface/yw_files/bak/'
#调用ftp连接函数
ftp = ftpconnect()
bufsize = 1024
ftp.cwd(remotepath)
list = ftp.nlst()
for name in list:
#正则过滤掉其他日期
L = re.match(d,name)
if L:
path = '/data/download/' + name
f = open(path,'wb')
filename = 'RETR '+name
ftp.retrbinary(filename,f.write,bufsize)
f.close()
ftp.quit()
downloadfile()