# OS Module

## The OS Module

### To import:

```python
import os
```

### Get current working directory

```python
# pwd in linux
os.getcwd()
```

### Change directory

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

### List content of directory

```python
# ls in linux
os.listdir()
```

### Make a folder

```python
# 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:

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

### Making multiple directories

```python
# 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

```python
# 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**

```python
# 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

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

### Rename files

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

## Traversing directories

```python
# 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

```python
# 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?

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

### Return just the filename

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

### Return just the directory

```python
# 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

```python
# 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

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

* Usually used as a if statement

### Check if directory exits

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

### Check if file exists

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

### Exclude file format

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


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