Module search path in Python - Step-by-Step Execution

Concept Flow - Module search path

Start: import module

↓

Check built-in modules

No↓

Check current directory

No↓

Check directories in sys.path one by one

↓

Load module

When Python imports a module, it looks in built-in modules, then current directory, then each folder in sys.path until it finds the module or raises an error.

Execution Sample

Python

import sys
print(sys.path)

This code prints the list of directories Python searches for modules.

Execution Table

Step	Action	Module Found?	Directory Checked	Result
1	Check built-in modules	No	N/A	Continue searching
2	Check current directory	No	./ (current folder)	Continue searching
3	Check sys.path[0]	No	/usr/lib/python3.12	Continue searching
4	Check sys.path[1]	Yes	/home/user/projects	Module loaded
5	End	N/A	N/A	Import successful

💡 Module found in /home/user/projects, search stops.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
module_found	False	False	False	False	True	True
directory_checked	None	built-in	current dir	/usr/lib/python3.12	/home/user/projects	/home/user/projects

Key Moments - 2 Insights

Why does Python check the current directory before sys.path folders?

Python checks the current directory early to allow importing modules from your working folder easily, as shown in execution_table step 2.

What happens if the module is not found in any directory?

If no directory has the module, Python raises ModuleNotFoundError after checking all sys.path entries, as implied after step 5.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the module found?

A Step 4

B Step 2

C Step 3

D Step 1

💡 Hint

Check the 'Module Found?' column in execution_table rows.

According to variable_tracker, what is the value of 'module_found' after step 3?

A True

B None

C False

D Error

💡 Hint

Look at the 'module_found' row under 'After Step 3' column in variable_tracker.

If the module was in the current directory, how would the execution_table change?

A Module Found? would be No at all steps

B Module Found? would be Yes at step 2

C Module Found? would be Yes at step 3

D Module Found? would be Yes at step 1

💡 Hint

Current directory is checked at step 2 in execution_table.

Concept Snapshot

Module search path in Python:
- Python looks for modules in this order:
  1. Built-in modules
  2. Current directory
  3. Directories in sys.path
- Stops at first found module
- If not found, raises ModuleNotFoundError

Full Transcript

When you import a module in Python, the interpreter searches for it in a specific order. First, it checks if the module is built-in. If not found, it looks in the current working directory. If still not found, it searches each folder listed in sys.path one by one. Once the module is found, Python loads it and stops searching. If the module is not found anywhere, Python raises a ModuleNotFoundError. This process helps Python know where to find the code you want to use.