Build a CLI Script to Bulk-Rename or Categorize Files

Objectives

By completing this lab, you will:

• Build a complete command-line tool using Python (or your preferred language).

• Apply loops, conditionals, and input validation.

• Use file operations (rename/move).

• Handle edge cases, errors, and add logging.

• Practice real-world problem solving with automation.

Choose a Project Option

You have two options. Pick one, or do both for extra practice:

Option A: Bulk-Rename Files

A script that renames all files in a given directory using a naming scheme (e.g., add prefix, suffix, or sequential numbering).

Option B: Categorize Files

A script that moves files into subfolders based on file types (e.g., .jpg → Images, .pdf → Documents).

Step-by-Step Instructions

Step 1: Setup and Planning

 Create a Test Folder:

• For Rename (Option A):
  Create a folder test_rename and add mixed files (e.g., file1.txt, image.png, doc.docx).

• For Categorize (Option B):
  Create a folder test_sort and add mixed types (e.g., photo1.jpg, report.pdf, song.mp3).
  Ensure no subfolders exist yet.

 Tip: Work on copies of files, not originals, to avoid data loss during testing.

Step 2: Outline the Logic in Pseudocode

Bulk-Rename – Pseudocode

BEGIN
PROMPT for folder path and new filename prefix
SET count = 1
FOR EACH file in folder:
    IF file is a directory, CONTINUE
    CONSTRUCT new_name = prefix + "_" + count + original extension
    RENAME file to new_name
    PRINT success message
    INCREMENT count
END FOR
PRINT "Renaming complete."
END

Categorize – Pseudocode

BEGIN
PROMPT for folder path
DEFINE categories = {
    "Images": [".jpg", ".png", ".gif"],
    "Documents": [".pdf", ".docx", ".txt"],
    "Audio": [".mp3", ".wav"]
}
FOR EACH file in folder:
    IF file is a directory, CONTINUE
    SET ext = file extension (lowercased)
    FOR EACH category:
        IF ext is in category list:
            SET dest_folder = category
            BREAK
    IF no category matched:
        SET dest_folder = "Others"
    IF dest_folder does not exist:
        CREATE it
    MOVE file to dest_folder
    PRINT move message
END FOR
PRINT "Categorization complete."
END

Step 3: Plan Edge Cases

•  Empty folders: Script should run without errors.

•  Duplicate prefixes (rename): Avoid double-renaming.

•  Filename collisions: Use numbering or unique naming.

•  Categorize: Prevent re-moving already sorted files.

•  Permissions issues: Catch and log exceptions.

•  Skip folders (only operate on files).

Step 4: Implement the Script

 Example: Python Script for Bulk Rename (Option A)

import os

# Get user inputs
folder = input("Enter folder path to rename files in: ").strip()
prefix = input("Enter new filename prefix: ").strip()

# Validate input
if not os.path.isdir(folder):
    print("Error: Folder not found.")
    exit(1)

count = 1

# Loop through files
for filename in os.listdir(folder):
    file_path = os.path.join(folder, filename)
    if os.path.isdir(file_path):
        continue  # Skip folders

    name, ext = os.path.splitext(filename)
    new_name = f"{prefix}_{count}{ext}"
    new_path = os.path.join(folder, new_name)

    try:
        os.rename(file_path, new_path)
        print(f'Renamed "{filename}" to "{new_name}"')
        count += 1
    except Exception as e:
        print(f'ERROR renaming "{filename}": {e}')

print("Renaming complete.")

 For File Categorization (Option B), use:

• os.makedirs(path, exist_ok=True) to create folders if missing.

• shutil.move(src, dst) or os.rename() to move files.

• Loop through categories and match file extensions.

Step 5: Testing

For Rename:

•  Check all files got renamed.

•  Confirm nothing was lost or skipped.

For Categorize:

•  Confirm folders like “Images”, “Documents”, “Audio” were created.

•  Check that files moved correctly.

Example Output – Categorize Script:

Created folder: Images
Moved photo1.jpg -> Images/photo1.jpg
Moved photo2.png -> Images/photo2.png

Created folder: Documents
Moved report.pdf -> Documents/report.pdf
Moved notes.txt  -> Documents/notes.txt

Created folder: Audio
Moved song.mp3   -> Audio/song.mp3

File categorization complete.

 Test Edge Cases:

• Empty folder

•  Subfolders present (should skip or handle)

•  Already processed files (optional skip logic)

•  Read-only or restricted files

•  Large number of files

Step 6: Review and Optimize

Optional enhancements:

• Add a mode selector: rename or categorize

• Skip already renamed or sorted files

• Add logging to a file (e.g., log.txt)

• Add an undo option (if you track original names)

• Add a dry-run mode to preview actions without making changes

Lab Summary

By the end of this lab, you will have:

 Identified a repetitive manual task
 Designed logic with pseudocode
 Used input handling, loops, and conditionals
 Performed file renaming or moving
 Tested and handled errors
 Built a working CLI script!