打印文件的绝对路径：
os.path.abspath(__file__)

os.path.dirname("/root/python/test.py")   #只取目录名
'/root/python'

os.path.dirname(os.path.dirname("/root/python/test.py"))   
'/root'

import os

BASE_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

sys.path.append(BASE_DIR)

>>> os.path.split('/etc/filebeat.yml')  #将路径名和文件名分开

('/etc', 'filebeat.yml')

>>> os.path.splitext('filebeat.yml')    # 将文件名和后缀名分开

('filebeat', '.yml')

>>> os.path.splitext('/etc/filebeat.yml')

('/etc/filebeat', '.yml')

>>> os.path.join('/home/www','testdir')  #拼接路径

'/home/www/testdir'

>>> os.path.isdir('data')  # 判断是否是目录

True

>>> os.path.isfile('data')  #判断是否是文件

False

>>> [ x for x in os.listdir('.') if os.path.isdir(x)] #列出当前目录下的所有目录

>>> [x for x in os.listdir() if os.path.isfile(x) and os.path.splitext(x)[1] == '.py']  #当前目录下所有后缀为.py的文件

os.walk（）方法 遍历树

os.walk(top[, topdown=True[, onerror=None[, followlinks=False]]])

top 要遍历的目录的地址。得到3个元组，(dirpath,dirnames,filenames)

topdown 为True(默认)时，则优先遍历top目录，自上而下遍历。  否则优先遍历top的子目录(默认为开启)，自下而上。

cd /root/test

# tree

.

|-- day1

|   |-- base.py

|   `-- day1.py

|-- day2

|   |-- day2.py

|   `-- day3

|       `-- a.txt

`-- test.py

directories, 5 files

>>> for paths,dirs,files in os.walk('/root/test'):

...      print(paths,dirs,files)

...

/root/test ['day1', 'day2'] ['test.py']

/root/test/day1 [] ['day1.py', 'base.py']

/root/test/day2 ['day3'] ['day2.py']

/root/test/day2/day3 [] ['a.txt']

>>> for paths,dirs,files in os.walk('/root/test'):

...      print(paths)

...

/root/test

/root/test/day1

/root/test/day2

/root/test/day2/day3

>>> for paths,dirs,files in os.walk('/root/test'):

...      print(dirs)

...

['day1', 'day2']

[]

['day3']

[]

>>> for paths,dirs,files in os.walk('/root/test'):

...      print(files)

...

['test.py']

['day1.py', 'base.py']

['day2.py']

['a.txt']

>>> for paths,dirs,files in os.walk('/root/test'):

...      for f in files:

...              print(os.path.join(paths,f))    #得到所有目录及子目录下的文件

...

/root/test/test.py

/root/test/day1/day1.py

/root/test/day1/base.py

/root/test/day2/day2.py

/root/test/day2/day3/a.txt

>>> for paths,dirs,files in os.walk('/root/test'):

...      for d in dirs:

...              print(os.path.join(paths,d))     #得到所有的目录和子目录

...

/root/test/day1

/root/test/day2

/root/test/day2/day3

os.walk()