#!/usr/bin/env python
#-*- coding=UTF8 -*-
import os
import os.path as op
def change_dir():
  '''
 該函數(shù)顯示及改變前目錄
 using chdir() to change current dir
    getcwd() can show the current working directory
  '''
  directory="/tmp"
  #使用getcwd()返回當(dāng)前目錄
  print os.getcwd()
  #chdir改變當(dāng)前目錄為：directory目錄
  os.chdir(directory)
  print os.getcwd()
def show_filesOfdir(whichDir):
  '''
 此函數(shù)只顯示目錄下的所有文件
 using listdir() to shows all of the file execpt directory
   join() function catenate 'whichDir' with listdir() returns values
   isfile() check that file is a regular file
   '''  
   #listdir() 函數(shù)顯示前目錄的內(nèi)容
  for file in os.listdir(whichDir):
 #利用join（）把whichDir目錄及l(fā)istdir（） 返回值連接起來(lái)組成合法路徑
    file_name = op.join(whichDir,file)
 #isfile（）函數(shù)可以判斷該路徑上的文件是否為一個(gè)普通文件
    if op.isfile(file_name):
      print file_name
def printaccess(path):
  ''' 
 顯示文件的最后訪問(wèn)時(shí)間，修改時(shí)間
 shows 'path' the last access time 
      getatime() return the time of last access of path
   stat() return information of a file,use its st_atime return the time of last access
   ctime() return a string of local time
  '''
  import time
  #利用ctime（）函數(shù)返回最后訪問(wèn)時(shí)間
  #getatime（）函數(shù)返回最后訪問(wèn)時(shí)間，不過(guò)是以秒為單位（從新紀(jì)元起計(jì)算）
  print time.ctime(op.getatime(path))
  #stat（）函數(shù)返回一個(gè)對(duì)象包含文件的信息
  stat = os.stat(path)
  #st_atime 最后一次訪問(wèn)的時(shí)間
  print time.ctime(stat.st_atime)
  print the modify time
  print "modify time is:",
  print time.ctime(op.getctime(path))
  print "modify time is:",
  #st_ctime 最后一次修改的時(shí)間
  print time.ctime(stat.st_ctime)
def isDIR(path):
  '''
 一個(gè)os.path.isdir()函數(shù)的實(shí)現(xiàn)
 Implement isdir() function by myself
  '''
  import stat
  MODE = os.stat(path).st_mode
  #返回真假值
  return stat.S_ISDIR(MODE)
if __name__== "__main__":
  change_dir()
  show_filesOfdir('''/root''')
  printaccess('/etc/passwd')
  print isDIR('/etc')