python自动拉取备份压缩包并删除3天前的旧备份

业务场景，异地机房自动拉取已备份好的tar.gz数据库压缩包，并且只保留3天内的压缩包文件，用python实现

#!/usr/bin/env python

import requests,time,os,datetime,platform
from threading import Thread

#cd backup dir
if platform.system() == 'Windows':
    os.chdir('D:\python\mysqlbackup_all')
elif platform.system() == 'Linux':
    os.chdir('/data/mysqlbackup_all/')

#Get 3 days ago
now_time = datetime.datetime.now()
yes_time = now_time + datetime.timedelta(days=-3)
yes_time_3day_ago = yes_time.strftime('%Y%m%d%H%M').replace('','')

#Get the whole point time
Data_time = time.strftime("%Y%m%d%H%M",time.localtime())
Data_time_30Minute = Data_time.replace('','')

#request url
def for_url(url_name):
    for i in url_name:

        file_url = 'http://186.87.1.98/'+i + '/'+ i + '_aaa_' + '' +'.tar.gz'

        r = requests.get(file_url, stream=True)
        with open(i + '_'+Data_time + '.tar.gz', 'wb') as didi:
            for chunk in r.iter_content(chunk_size=1024 * 1024):
                if chunk:
                    didi.write(chunk)
        print file_url

#delete 3 day ago tar.gz file
def delete_3day(url_name):
    for i in url_name:
        targat_dir = i + '_' + yes_time_3day_ago + '.tar.gz'
        delete_home_ssdb = 'rm %s -rf ' % targat_dir
        os.system(delete_home_ssdb)

def main():
    url_name = ('', '', '', 'aa', 'qq', 'baidu', '')
    t = Thread(target=for_url(url_name),args=url_name)
    t.start()
    t.join()
    delete_3day(url_name)

if __name__ == '__main__':
     main()