Python文件操作相关问题

1、修改文件内容并写回原文件

with open(filename) as f:
    file_str = f.read()

# do stuff with file_str

with open(filename, 'w') as f:
    f.write(file_str)

2、重命名(移动/剪切)文件或文件夹

os.rename(src, dst)
shutil.move(src, dst)

3、删除文件或文件夹

os.remove()       # will remove a file
os.rmdir()        # will remove an empty directory
shutil.rmtree()   # will delete a directory and all its contents

4、检查文件或文件夹是否存在

os.path.isfile(path) # check file exists
os.path.isdir(path)  # check directory exsits
os.path.exists(path) # check file or directory exists

5、如果文件夹不存在则创建

if not os.path.exists(directory):
    os.makedirs(directory)

6、检测文件夹为空则删除

try:
    os.rmdir(directory)
except OSError:
    pass

7、从路径中提取文件名和目录名

os.path.dirname(path)从path中提取目录，os.path.basename(path)从path中提取文件名。

>>> import os
>>> path = '/usr/bin/python'
>>> os.path.dirname(path)
'/usr/bin'
>>> os.path.basename(path)
'python'

os.path.split(path)分割路径成目录(os.path.dirname(path))和文件(os.path.basename(path))。

>>> import os
>>> path = '/usr/bin/python'
>>> head, tail = os.path.split(path)
>>> head
'/usr/bin'
>>> tail
'python'
>>>

8、复制文件

shutil.copyfile(src, dst) : Copy the contents (no metadata) of the file named src to a file named dst and return dst.

shutil.copy(src, dst) : Copies the file src to the file or directory dst.

shutil.copy2(src, dst) : Identical to copy() except that copy2() also attempts to preserve all file metadata.

shutil.copyfileobj(fsrc, fdst) : Copy the contents of the file-like object fsrc to the file-like object fdst.

9、统计某一文件夹下文件数量

>>> import os
>>> DIR = '/tmp'
>>> print len([name for name in os.listdir(DIR) if os.path.isfile(os.path.join(DIR, name))])

如统计文件夹数量，用os.path.isdir(path)做判断语句。

10、递归查找文件

Python 3.5+
从Python 3.5版本起，glob模块支持”**”语法，此时必须设置recursive标志。如果匹配的路径是list，则用glob.glob代替glob.iglob。

import glob

for filename in glob.iglob('src/**/*.html', recursive=True)
    print(filename)

Python 2.2 to 3.4
对于老版本从Python 2.2以上的，用os.walk递归遍历目标文件夹，然后用fnmatch.filter匹配简单的通配符表达式。

import fnmatch
import os

for root, dirnames, filenames in os.walk('src'):
    for filename in fnmatch.filter(filenames, '*.py'):
        print(os.path.join(root, filename))

11、按行读取文件内容到list并去除换行

with open(path) as f:
    lines = f.read().splitlines()

12、检查文件夹下是否有文件

for root, dirnames, filenames in os.walk('.'):
    if filenames:
        print(root,'has files')
    if not filenames:
        print(root,'is empty')