python創建和刪除文件

#!/usr/bin/python
#-*-coding:utf-8-*-       #指定編碼格式，python默認unicode編碼

import os
directory = "./dir"
os.chdir(directory)  #切換到directory目錄
cwd = os.getcwd()  #獲取當前目錄即dir目錄下
print("------------------------current working directory------------------")

def deleteBySize(minSize):
    """刪除小於minSize的文件（單位：K）"""
    files = os.listdir(os.getcwd())  #列出目錄下的文件
    for file in files:
        if os.path.getsize(file) < minSize * 1000:
            os.remove(file)    #刪除文件
            print(file + " deleted")
    return

def deleteNullFile():
    '''刪除所有大小為0的文件'''
    files = os.listdir(os.getcwd())
    for file in files:
        if os.path.getsize(file)  == 0:   #獲取文件大小
            os.remove(file)
            print(file + " deleted.")
    return

def create():
    '''根據本地時間創建新文件，如果已存在則不創建'''
    import time 
    t = time.strftime('%Y-%m-%d',time.localtime())  #將指定格式的當前時間以字符串輸出
    suffix = ".docx"
    newfile= t+suffix
    if not os.path.exists(newfile):
        f = open(newfile,'w') 
        print newfile
        f.close()
        print newfile + " created."
    else:
        print newfile + " already existed."
    return
hint = '''funtion:
            1   create new file
            2   delete null file
            3   delete by size
please input number:'''
while True:
    option = raw_input(hint)  #獲取IO輸入的值
    if cmp(option,'1') == 0:
        create()
    elif cmp(option,'2') == 0:
        deleteNullFile()
    elif cmp(option,'3') == 0:
        minSize = raw_input("minSize(K):")
        deleteBySize(minSize)
    elif cmp(option,'q') == 0:
        print "quit !"
        break
    else:
        print ("disabled input ,please try again....")