OS Module

The OS Module

To import:

import os

Get current working directory

# pwd in linux
os.getcwd()

Change directory

# cd in linux
os.chdir("/Path/To/Wanted/Directory")

List content of directory

# ls in linux
os.listdir()

Make a folder

# mkdir in linux
os.mkdir("Name_of_folder_you_want")

• Can only be run once, as if the folder exists an error will be generated

  • [Errno 17] File exists: folder_name

• Adding a conditional to check if the folder exits:

# os.listdir = lsdir in linux
if "myfolder" not in os.listdir("~/Desktop"):
	os.mkdir("myfolder")

Making multiple directories

# mkdir -p /path/to/folder in linux
os.makedirs("/path/to/folder")

• This can be run once for the same reasons as making a folder

Remove directory

# rmdir /path/to/directory in linux
os.rmdir("/path/to/directory")

• If the folder is not empty it will not delete it, same as Linux

• os.rmdir does not work on files, same as rmdir in Linux

To remove in general, it is same as Linux

# rm /path/to/file in linux
os.remove("/path/to/file")

• Can be run only once if the file does not exits

• To prevent this, you can use the same if statement check in order to see if it exists

# rm -rf /path/to/directory in linux
os.removedirs("/path/to/directory")

Rename files

# mv current_name new_name in linux
os.rename("current_name", "new_name")

Traversing directories

# Unpacking
for directory_path, dirnames, filenames in os.walk("/location/to/folder"):
	print(directory_path)
	print(dirnames)
	print(filenames)

• By "walking":

  • The first variable prints the path to the file

  • The second variable prints the folders inside the path provided

  • The third variable prints the files inside the path provided

• After which, if it finds a folder it goes on level deeper within the directory structure

• After which it starts the process again

• If multiple folders, it will take them separately and "walk" through them until the end

Getting the environment variable

# Getting the HOME variable
# echo $HOME in linux
os.environ.get("HOME")

Join method

• Usually used when the path to folder is questionable

  • Such as does it contain a / at the end or not?

# Concatinates basically ~/my_file.txt
os.path.join(os.environ.get("HOME"), "my_file.txt")

Return just the filename

# Will return just file.txt
print(os.path.basename("/path/to/file.txt"))

Return just the directory

# Will return just the "/path/to" folder structure, not the file
print(os.path.dirname("/path/to/file.txt"))

Return both directory path and filename separately

# Will return a tuple with directory and filename
print(os.path.split("/path/to/file.txt"))
# Example tuple: ("/path/to", "file.txt")

Check if path exists

# Boolean expression
os.path.exists("/path/to/file.txt")
# Returns True or Flase

• Usually used as a if statement

Check if directory exits

os.path.isdir("/path/to/file.txt")

Check if file exists

os.path.isfile("/path/to/file.txt")

Exclude file format

# Prints the entire path + extension in tuple
os.path.splitext("/path/to/file.txt")
# Example: ("/path/to/file", ".txt")