Bash Script - Task Management

A Simple Guide to a Bash Task Management Script

This article explains a basic task management script written in Bash. The script lets users create tasks, view them, mark them as completed, and delete them. Let’s go through the code step by step.

Overview of the Script

The script has several functions, each doing a specific job for managing tasks. It runs a loop that shows a menu to the user until they choose to exit.

1. Shebang Line

#! /bin/bash

This line tells the system to use the Bash shell to run the script.

2. Creating the Task File

create_file() {
    if [ -f 'tasks.txt' ]; then
        echo "File exists"
        echo ''
    else
        touch tasks.txt
        echo "File created"
        echo ''
    fi
}

• Purpose: Checks if tasks.txt exists. If it does, it tells the user. If not, it creates the file.
• -f: Checks if the file exists.
• touch: Creates an empty file if it doesn’t already exist.

3. Displaying the Menu

display_menu() {
    echo "1. Add task"
    echo "2. View all tasks"
    echo "3. Mark task as completed"
    echo "4. Delete task"
    echo "5. Exit"
    echo ''
}

• Purpose: Shows a simple menu for the user to choose from.
• The menu offers options to add, view, mark, delete tasks, or exit the program.

4. Adding a Task

add_task() {
    read -p "Enter task: " task
    if grep -q "$task:Pending" tasks.txt; then
        echo "Task already exists"
        echo ''
        return
    elif grep -q "$task:Completed" tasks.txt; then
        echo "Task already exists"
        echo ''
        return
    fi
    echo "$task:Pending" >> tasks.txt
    echo "Task added"
    echo ''
}

• Purpose: Asks the user to enter a task and adds it to tasks.txt with the status "Pending".
• grep -q: Searches the file quietly to check for duplicates.
• Appending: The task is added to the file with the status Pending.

5. Viewing All Tasks

view_tasks() {
    cat tasks.txt
    echo ''
}

• Purpose: Shows all tasks in tasks.txt.
• cat: Reads the file and displays its contents.

6. Marking a Task as Completed

mark_task() {
    read -p "Enter task to mark as completed: " task
    echo ''
    if grep -q "$task:Pending" tasks.txt; then
        sed -i '' "s/$task:Pending/$task:Completed/g" tasks.txt
        echo "Task marked as completed"
        echo ''
    else
        echo "Task not found or already completed"
        echo ''
    fi
}

• Purpose: Lets the user mark a task as completed.
• sed -i '': Changes the status from "Pending" to "Completed" in the file.
• Feedback: Tells the user if the task was found and updated.

7. Deleting a Task

delete_task() {
    read -p "Enter task to delete: " task
    echo ''
    if grep -q "$task:Pending" tasks.txt; then
        sed -i '' "/$task:Pending/d" tasks.txt
        echo "Task deleted"
        echo ''
    elif grep -q "$task:Completed" tasks.txt; then
        sed -i '' "/$task:Completed/d" tasks.txt
        echo "Task deleted"
        echo ''
    else
        echo "Task not found"
        echo ''
    fi
}

• Purpose: Deletes a task from the file.
• /pattern/d: Removes lines that match the pattern from the file.
• Feedback: Informs the user whether the task was deleted or not found.

8. User Input Handling

user_input() {
    read -p "Enter your choice: " choice
    echo ''
    case $choice in
        1) add_task ;;
        2) view_tasks ;;
        3) mark_task ;;
        4) delete_task ;;
        5) echo "Exiting..." ;;
        *) echo "Invalid choice"
    esac

    return $choice
}

• Purpose: Gets user input and runs the correct function based on the choice.
• case statement: Handles multiple options more clearly than using many if statements.

9. Main Program Loop

create_file

while true; do
    display_menu
    user_input

    if [ $? -eq 5 ]; then
        echo ''
        break
    fi
done

• Purpose: Sets up the task file and runs a loop to show the menu until the user decides to exit.
• $?: Gets the exit status of the last command (in this case, user_input).

Conclusion

This Bash script is a simple task manager. It shows basic Bash scripting concepts like functions, file handling, user input, and control flow. With a few changes, this script can be improved to add more features, like saving task priorities or due dates.

Script can be found here

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