LINUX SHELL SCRIPTING

Table of Contents

1. Project Overview
2. Project Steps and Commands
   • 2.1 Create Project Directory
   • 2.2 Initialize Git Repository
   • 2.3 Create the Bash Script File (.sh)
   • 2.4 Make the Script Executable
   • 2.5 Set Up GitHub Repository and Link Remote
3. Script Implementation Steps
   • 3.1 Prompt for User Input
   • 3.2 Ask for Table Type (Full or Partial)
   • 3.3 Full Multiplication Table
   • 3.4 Partial Multiplication Table
   • 3.5 Validate Input Range for Partial Table
   • 3.6 Handle Invalid Options
4. Troubleshooting (Common Issues and Solutions)
   • 4.1 Script Permission Denied
   • 4.2 Invalid Input for Number
   • 4.3 Invalid Range in Partial Table
   • 4.4 Git Remote Connection Issues

1. Project Overview

This project involves creating a Bash script that generates a multiplication table for a given number using both list-style and C-style for loops. The script provides an option to display the table either in ascending or descending order, and the user can choose to view a full table (from 1 to 10) or a partial table with a custom range. The project is managed with Git, including initializing a local repository, committing changes, and pushing updates to GitHub.

2. Project Steps and Commands

2.1. Create Project Directory

• First, create a project directory where all files for the project will be stored.

  

2.2 Initialize Git Repository

• Initialize a Git repository in the project directory to track changes.
• Command:

git init

2.3. Create the Bash Script File (.sh)

• Create a shell script file named multiplication_table.sh where the Bash code will be written.
• Command: touch multiplication-table.sh

2.4. Make the Script Executable

• Change the file permissions to make the script executable.
• Command: chmod +x multiplication-table.sh

2.5. Set Up GitHub Repository and Link Remote

• Create a new repository on GitHub, then add the remote link to your local Git repository.

3. Script Implementation Steps

3.1. Prompt for User Input

• Use read to prompt the user to enter a number for which the multiplication table will be generated.

echo "Enter a number:"
read number

3.2. Ask for Table Type (Full or Partial)

• Ask the user if they want a full multiplication table (1 to 10) or a partial one within a specific range.

echo "Do you want a full table or partial table? (Enter 'f' for full, 'p' for partial)"
read table_type

3.3. Full Multiplication Table

• If the user selects the full table option (f), display the multiplication table from 1 to 10 in ascending order.

if [ "$table_type" == "f" ]; then
    # Generate the full multiplication table in ascending order
    echo "Multiplication table for $number (Ascending):"
    for i in {1..10}
    do
        result=$((number * i))
        echo "$number x $i = $result"
    done

3.4. Partial Multiplication Table

• If the user chooses the partial option (p), prompt for a custom range (start and end numbers).

elif [ "$table_type" == "p" ]; then
    # Prompt for the start and end numbers of the range
    echo "Enter the start number of the range:"
    read start
    echo "Enter the end number of the range:"
    read end

3.5. Validate Input Range for Partial Table

• Check if the start and end numbers form a valid range. If valid, display the multiplication table within the specified range; otherwise, show an error message.

# Validate the range
if [ $start -le $end ]; then
    echo "Multiplication table for $number from $start to $end:"
    for i in $(seq $start $end)
    do
        result=$((number * i))
        echo "$number x $i = $result"
    done
else
    echo "Invalid range. The start number must be less than or equal to the end number."
fi

3.6. Handle Invalid Options

• Provide feedback if the user enters an invalid option for the table type.

 echo "Invalid option. Please enter 'f' for full table or 'p' for partial table."
fi

4. Troubleshooting (Common Issues and Solutions)

4.1. Script Permission Denied

- If you encounter a “Permission Denied” error when running the script, ensure the script has executable permissions.
- Solution: Run chmod +x multiplication_table.sh to make the script executable.

4.2. Invalid Input for Number

- If the user enters a non-numeric value, the script may behave unexpectedly as it expects a number for multiplication.
- Solution: Add input validation to ensure that only numbers are accepted. For example:

```sh 
if ! [[ "$number" =~ ^[0-9]+$ ]]; then
echo "Invalid input. Please enter a valid number."
exit 1
fi
```

4.3. Invalid Range in Partial Table

- If the user inputs a start number greater than the end number, the script will display an "Invalid range" error.
- Solution: Make sure the start number is less than or equal to the end number, as shown in the range validation code.

4.4. Git Remote Connection Issues

- If you have trouble pushing code to the GitHub repository, verify that the remote URL is correct and that you have the necessary permissions.
- Solution: Run git remote -v to check the remote URL and verify access. If there are issues, re-add the remote with the correct URL using git remote add origin <repository_url>.