README for Username Validation Script

Author Information

• Name: [Your Full Name]
• Course: [Course Number and Name]
• Assignment: Username Validation
• Date: [Date of Completion]

Program Description

[Write 2-3 sentences in your own words describing what this script does and its purpose. Explain the problem it solves and how it works at a high level.]

Username Requirements

This script validates usernames according to the following rules:

• Must start with a lowercase letter
• Can only contain lowercase letters, digits, and underscores
• Must be between 3 and 12 characters in length (inclusive)

Usage

To run the script interactively:

./username.sh

To test with the provided input file:

./username.sh < username-input

How the Script Works

[Explain in 3-5 sentences how your script validates usernames. Include information about:]

• The use of the while loop
• The grep command with extended regular expressions
• The meaning of the -E and -v flags
• The redirect > /dev/null 2>&1

Regular Expression Pattern

The validation uses the following regular expression pattern:

^[a-z][a-z0-9_]{2,11}$

This pattern ensures that:

• The username starts with a lowercase letter [a-z]
• The following characters are lowercase letters, digits, or underscores [a-z0-9_]
• The total length is between 3 and 12 characters

Testing Results

[Describe your testing process and results. Include:]

• Example valid usernames you tested (at least two)
• Example invalid usernames and why they fail (at least two)
• How you used the username-input file to test

Challenges and Solutions

[Optional: Describe any challenges you encountered while creating this script and how you solved them. This could include debugging issues, understanding regular expressions, or Git workflow problems.]

Resources

[List any resources you used (class slides, ChatGPT, etc.). Please refer to the course syllabus for more details on citations.]

License

This project is part of coursework for Chapman University and is intended for educational purposes.