# 
## Overview
The **`os`** module in Python provides functions that help us interact with the underlying operating system. 

The **`unsetenv()`** method is used to delete the given environment variable. The deletion affects the subprocesses created by the following method calls:

1. `os.system()`
2. `os.popen()`
3. `os.fork()`
4. `os.execv()`

Using `os.unsetenv()` doesn't actually delete the keys stored in the `os.environ`. Instead, we can use the `del` operator or the `pop` method on the `os.environ` dictionary.

> **Note**: Refer to this [link](https://www.educative.io/answers/how-to-list-all-the-environment-variables-in-python) to learn more about `os.environ`.

## Syntax

```
os.unsetenv(key)
```

## Parameter values

- **`key`**: The environment key to be deleted.

## Code example

import os

print(os.environ["educative"])

import os

os.environ["educative"] = "awesome"

print("The current environment variables are:")
print(os.environ)

os.unsetenv("educative")

print("Executing child.py")
os.system("python child.py")

print("Is the key 'educative' still present in the os.environ dictionary?", "educative" in os.environ)


## Explanation

### `child.py`
This Python script tries to print the environment variable `educative`.

### `main.py`
- Line 1: We import the `os` module.
- Line 3: We create a new environment variable called `educative` whose value is `awesome`.
- Lines 5–6: We print the current environment variables.
- Line 8: We invoke the `unsetenv()` method and pass `educative` as the parameter.
- Lines 10-11: We execute the `child.py` script using the `os.system()` call. This method throws an error indicating that the `educative` key is not found in the `os.environ` dictionary. This indicates that `unsetenv()` affects the child's process environment only. 
- Line 13: We check if the `educative` key is still present in the `os.environ` dictionary.

What is the os.unsetenv() method in Python?

The os.unsetenv() method in Python deletes an environment variable for subprocesses, without removing keys from os.environ directly.