1. Python OS Module

• Python OS module provides the facility to establish the interaction between the user and the operating system
• It provides functions for creating and removing a directory (folder), fetching its contents, changing and identifying the current directory, etc.

import os

# shows all attribute and method in this module.
print(dir(os))

1.1 Common OS functions

• os.getcwd()
  • Get current working directory(cwd)
• os.listdir()
  • list/display files and dir
• os.chdir()
  • Change dir/folder

print(os.getcwd())
# /home/user/Desktop

print(os.listdir())
# ['file1.py', 'dir1', 'file2.py]

# Change dir
os.chdir('dir1/')

• os.mkdir()
  • Create dir/folder, if exist shows error
• os.makedirs()
  • Create multi level dir

# Create dir
os.mkdir('newDir1')
os.makedirs('dir2/dir')

• os.rename()
  • Rename files n dir, if exist replace

os.rename('newDir1','newDir2')

• os.remove()
  • Delete only files
• os.rmdir()
  • Delete only empty dir
• os.removedirs()
  • Delete dir and its contents

os.remove('file1.py')

os.rmdir('newDir2')
os.rmdir('dir2/dir/')

os.removedirs('dir2/dir')

• os.system()
  • executing a shell command.

os.system('pwd')
os.system('ls')

1.2 OS Path

• os.path.exists()
  • True if path exist else False
• os.path.getsize()
  • Gives the size of the file/dir in bytes.
• os.path.isdir()
  • True if path is dir else False
• os.path.isfile(path)
  • True if path is file else False

os.path.exists('dir2')
size = os.path.getsize("file1.py")

os.path.isdir('dir2')
# True

os.path.isfile("C:\\Users\foo.csv")
# True

• os.path.join()
  • Joins one or more path components
• os.path.abspath()
  • Returns absolute/full path.

path = "/home"
print(os.path.join(path, "User/Desktop", "file.txt"))
# /home/User/Desktop/file.txt

print(os.getcwd()+'newfile.txt')    # '/' slash problem
print(os.path.join(os.getcwd(),'newfile'))  #better solution


print(os.path.abspath(__file__))
print(os.path.abspath('file.txt'))
# /home/User/Desktop/file.txt

print(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
print(os.path.dirname(os.path.dirname(os.path.abspath('file.txt'))))
# /home/User

1.3 Additional OS Fxn

• os.environ
  • Get all env(System,Users) variables
• os.environ.get()
  • Get the specific env

os.environ.get('HOME')
# '/home/uxer'

# Add a new environment variable 
os.environ['myenv'] = 'envVar'

• os.path.basename()
  • base name of the specified path.
• os.path.dirname()
  • base dir of the specified path.
• os.path.split()
  • split dir and file name

print(os.path.basename('/temp/test.txt'))
# test.txt

print(os.path.dirname('/temp/test.txt'))
# /temp

print(os.path.split('tmp/temp/test.txt'))
# ('tmp/temp', 'test.txt')

• os.walk()
  • shows all dir, sub-dir, files from the given location

print(list(os.walk(os.getcwd()))) 
for dirpath, dirnames, filesname in os.walk('/home/dev/Desktop/'):
    print('curr path: ',dirpath)
    print('dirs: ',dirnames)
    print('files: ',filesname)
    print()

• os.stat()
  • This method is used to get status of the specified path.

# st_size= size of file
# st_mtime = last modified timestamp

print(os.stat('demo.json'))
print(os.stat('demo.json').st_size)

from datetime import datetime
# converting timestamp to redable form
print(datetime.fromtimestamp(os.stat('demo.json').st_mtime))