How To Run Python Script In Loop

In this tutorial, we will learn how to run a Python script in a loop. Running a script in a loop can be useful in various contexts like web scraping, checking server status, running scheduled tasks, and more. We will explore different ways to run a Python script in a loop, such as using a while loop, a for loop, and a crontab.

Moreover, we will discuss how to execute an external Python script inside a loop, which can be especially useful when working with larger, more complex scripts. By the end of this tutorial, you will be able to run your Python script in a loop and know multiple ways to efficiently achieve your desired looping behavior.

Step 1: Basic While Loop

A simple way to run a Python script in a loop is to use a while loop. In this example, we will print “Hello, World!” five times in a loop.

Create a file called loop.py containing the following code:

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counter = 0
 
while counter < 5:
    print("Hello, World!")
    counter += 1

Execute the script by running python loop.py, and you will see the following output:

Hello, World!
Hello, World!
Hello, World!
Hello, World!
Hello, World!

Step 2: For Loop

Another way to run a Python script in a loop is to use the for loop. The below example demonstrates how you can use a for loop to print the numbers 0 through 9.

Modify the loop.py file to contain the following code:

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for i in range(10):
    print(i)

Execute the modified script by running python loop.py, and you will get the following output:

0
1
2
3
4
5
6
7
8
9

Step 3: Executing an External Python Script in a Loop

In this step, we will learn how to execute an external Python script within a loop. This can be particularly useful when dealing with larger scripts or multiple scripts that need to be executed sequentially.

Create a new file called external_script.py containing the following code:

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def print_message():
    print("This is an external Python script.")
 
if __name__ == "__main__":
    print_message()

Now, modify your loop.py file to incorporate the following code:

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import os
 
for _ in range(3):
    os.system('python external_script.py')

Execute the modified loop.py script by running python loop.py, and you will get the following output:

This is an external Python script.
This is an external Python script.
This is an external Python script.

Step 4: Using Crontab on Unix-based Systems

Crontab is a Unix-based utility that allows you to schedule tasks to run automatically at specific intervals. You can use crontab to execute a Python script periodically.

To schedule your loop.py to run every minute, open your terminal and type crontab -e. This will open the crontab configuration file in your default text editor.

Add the following line to the end of the file:

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* * * * * /usr/bin/python [absolute_path_to_your_python_script]/loop.py

Replace [absolute_path_to_your_python_script] with the full directory path containing the loop.py script. Save and close the file.

Your Python script will now run every minute. To remove the scheduled task, edit the crontab file again by typing crontab -e, delete the previously added line, and save the file.

Conclusion

In this tutorial, we learned how to run a Python script in a loop using while loops, for loops, as well as executing an external Python script within a loop. Additionally, we explored how to schedule a Python script to run periodically using crontab on Unix-based systems. Depending on your specific use case, you can choose to use any of these methods to run your Python script in a loop efficiently.