COMP7004 - Systems Scripting

Lecture 15: Organising Files

Dr. Vincent Emeakaroha

vincent.emeakaroha@mtu.ie

Semester 2, 2026

Objectives

• Python provides the ability to organise pre-existing files on

a hard drive. This enables automating boring tasks such as:

• Making copies of all PDF files (and only the PDF files) in

every sub-folder of a folder.

• Removing the leading zeros in the filename for every file in

a folder of hundreds of files named as cat001.txt,

cat002.txt, cat003.txt, and so on.

• Compressing the content of several folders into one ZIP file

(which could be a simple backup system).

Accessing User Home Directory

• Python provides a function in the os module to return

a user home directory.

• The function

• os.path.exapanduser()

• Passing tilda (~) as parameter to this function ensure

interoperability across platforms.

• Example

Copying Files and Folders

• The shutil (or shell utilities) module provides functions

for copying files, as well as entire folders.

• To copy a file, we can call shutil.copy(source,

destination). This will copy the file at the path source

to the folder at the path destination. Both source and

destination are string data type.

• If the destination is a filename, it will be used as the

new name of the copied file. This function returns a

string of the path of the copied file.

Copying Files and Folders

• While shutil.copy() will copy a single file, shutil.copytree() will copy an

entire folder and every subfolders and files contained in it.

• Calling shutil.copytree(source, destination) will copy the folder at the

path source, along with all of its files and subfolders, to the folder at

the path destination. The source and destination parameters are both

strings.

• It returns a string of the path of the copied folder.

Moving and Renaming Files and

Folders

• The shutil module provides the shutil.move() function for

this purpose.

• Calling shutil.move(source, destination) will move the le or

folder at the path source to the path destination and will

return a string of the absolute path of the new location.

• If destination points to a folder, the source le gets moved

into destination and keeps its current lename. See

following example.

• If the lename exist in the destination folder, it will be

silently overwritten.

Moving and Renaming Files and

Folders

• If the folder “backup” is not existing, the function will

rename the file “tips.txt” into “backup” at the path

destination. Be careful in using this function.

• The destination path can also specify a filename. In this

case, the source filename will be renamed to the name

specified at the destination path.

Permanently Deleting Files and

Folders

• One can delete a single file or a single empty folder with

functions in the os module, whereas for a non-empty folder

and all of its contents, we use the shutil module.

• Calling os.unlink(path) will delete a file at the specified path.

• Calling os.rmdir(path) will delete a folder at the specified path. The

folder must be empty of any files or folders.

• Calling shutil.rmtree(path) will remove the folder at the specified

path and all files and folders it contains will be deleted too.

• Be very careful in using these functions. It is a good idea to first

print out the content intended to be deleted before calling

these delete function on the content to avoid mistakenly

deleting important files.

Deleting Files: Example

• This will permanently delete all the files in the current

working directory that has the ending “.rxt”.

• Always print out the file names first to know exactly the

files you are about to delete.

Safe Deletes with the send2trash

Module

• Since Python’s built-in shutil.rmtree() function irreversibly

deletes files and folders, it can be dangerous to use.

• A much better way to delete files and folders is with the third-

party send2trash module.

• The send2trash module can be installed from a Terminal

window by simply running python3 –m pip install send2trash.

• Using send2trash is much safer because it will send folders

and files to your computer’s recycle bin or trash instead of

permanently deleting them.

send2trash Module: Example

• While sending files to the recycle bin lets you recover them

later, it will not free up disk space like permanently deleting

them does. If you want your program to free up disk space, use

the os and shutil functions to delete file and folders.

• Note that the send2trash() function can only send files to the

recycle bin, it cannot pull files out of it.

Walking a Directory Tree

• Let assume you want to rename every file in some folder

and also every file in every subfolder of that folder. That is,

you want to walk through the directory tree touching each

file as you go.

• Python provides the os.walk() function to handle this

process for you. This function accepts a single value – the

path of a folder.

• You can use os.walk() in a for loop statement to walk a

directory tree, much like how you can use the range()

function to walk over a range of numbers.

Walking a Directory Tree

• Unlike range(), the os.walk() function will return three

values on each iteration through the loop:

1. A string of the current folder’s name.

2. A list of strings of subfolders in the current folder

3. A list of strings of the files in the current folder

• Note that the current folder means the folder for the

current iteration of the for loop. The current working

directory of the program is not changed by os.walk()

function.

• See the following example.

Walking a Directory Tree: Example

• Just like you can choose the variable name ’i’ in a for loop,

you can choose variable names for the three values.

• One can use a loop to iterate over the three variables.

Walking a Directory Tree: Example

Output

Compressing Files with the zipfile

Module

• Compressing a file reduces its size, which is useful for

transferring it over the Internet.

• A Zip file can contain multiple files and subfolders. So

it is a handy way to package several files into one

archive.

• Python can both create and open (or extract) Zip files

using functions in the zipfile module.

Reading ZIP Files

• To read the content of a ZIP le, you must rst create a

ZipFile object (note the capital letters Z and F).

• ZipFile objects are conceptually similar to the File object

we saw returned by the open() function previously. They

are values through which the program interacts with the

le.

• To create a ZipFile object, call ziple.ZipFile() function,

passing it a string of the .zip le’s lename.

• Note that ziple is the name of the Python module, and

ZipFile() is the name of the function.

Reading ZIP Files: Example

Creating and Adding to ZIP Files

• To create your own compressed ZIP files, you must open the ZipFile

object in write mode by passing ‘w’ as the second argument.

• When you pass a path to the write() method of a ZipFile object, Python

will compress the file at that path and add it into the ZIP file.

• The write() method’s first argument is a string of the filename to add.

The second argument is the compression type parameter, which tell

the computer what algorithm it should use to compress the file. You

can just set this value to zipfile.ZIP_DEFLATED.

• See the following example:

Creating and Adding to ZIP Files

• Keep in mind that, just as with writing to les, write mode will erase all

existing content of a ZIP le.

• If you want to add le to an existing ZIP le, pass ‘a’ as the second

argument to ziple.ZipFile() to open the ZIP le in append mode.

Output showing created ZIP file

Extracting from ZIP Files

• Calling the extractall() method on ZipFile objects extracts all the files

and folders from a ZIP file into the current working directory.

• Example:

• Optionally, you can pass a folder name as an argument to extractall()

to have it extract the files in a folder other than the current working

directory. If the folder name passed does not exist, it will create it.

Extracting from ZIP Files

• The extract() method for ZipFile object will extract a single file

from the ZIP file.

• Let us continue with the previous example:

• The string you pass to extract() must match one of the strings

in the list returned by namelist(). You can optionally, pass a

second argument to extract() to extract to a folder other than

the current working directory. Python will create the folder if it

does not exist.

Use Case Scenario: Backing Up a

Folder

• Say you are working on a project whose files you keep in a folder

name /home/vin/progProject. You are worried about loosing your

work, so you would like to create ZIP file snapshots of the entire

folder.

• You would like to keep different versions, so you want the ZIP file’s

filename to increment each time it is made.

• For example:

• progProject_1.zip, progProject_2.zip, progProject_3.zip and so on.

• You could do this by hand but it is rather annoying and you might

accidentally misnumber the ZIP files’ names. It would be much

simpler to run a program that does this boring task for you.

Step1: Figure out the ZIP File’s

Name

• The whole program will be written as a Python function so that

it will be easy to reuse it in different Python programs.

• We will create a function that takes one parameter as

argument. The parameter will represent the path to the folder

name.

• To name the ZIP file, we will extract the base name from the

folder path. We can then concatenate it with a running number

count.

• Before a new folder with incremented count number is created,

we have to first check whether it already exist using the

os.path.exists() function.

Working Solution Structure

Step2: Create the New ZIP File

• Now that the new ZIP file’s name is stored in the

zipFilename variable, you can call zipfile.ZipFile()

function to actually create the ZIP file.

• Be sure to pass ‘w’ as second argument so that the

ZIP file is opened in write mode.

Step3: Walk the Directory Tree and

Add to ZIP File

• You can use os.walk() function in a for loop to iterate

over the directories.

Complete Solution

Thank You!