python数据库备份

import os,datetime
class BakDb(object):
   def __init__(self,ip,username,passwd,port=3306,path='/tmp/db_bak'):
      self.ip = ip
      self.username = username
      self.passwd = passwd
      self.port = port
      self.path = path
      self.path_exist()
      self.bak_db()
   def path_exist(self):
      if not os.path.isdir(self.path): #不存在的话就创建
         os.mkdir(self.path)
   def bak_db(self):
      filename = str(datetime.date.today())+'.sql'
      abs_file = os.path.join(self.path,filename) #变成绝对路径
      command = '''
      mysqldump -u{username} -p{passwd} -P{port} -h{ip} -A > {filename}
      '''.format(username=self.username,
               passwd=self.passwd,
               port=self.port,
               filename=abs_file,
               ip=self.ip)
      os.system(command)
      print('done!数据库备份完成！')

#db1 = BakDb('192.168.12.1','root','123456')


#小练习：统计字典中相同数字出现次数并排序
a = [1, 1, 2, 3, 4, 4, 4, 5]
b = {}

for i in a:
    if i in b:
        count = b[i] + 1
        b[i] = count
    else:
        b[i] = 1

dict = sorted(b.items(), key=lambda b: b[1], reverse=True)  # 字典排序

for i in range(2):
    k = dict[i][0]
    v = dict[i][1]
    print(k, v)