Spinner Animation and echo command

ONLINECAST

2 min read

·

05-09-2024

13

0

Share

Adding a Spinner Animation to Your Bash Script: A Step-by-Step Guide

Have you ever wanted to add a visually engaging spinner animation to your bash scripts? Maybe you're working on a long-running process and want to give users some feedback that things are happening. This is where a simple spinner animation can be incredibly useful!

This article will guide you through creating a spinner animation using the echo command and a bash function, inspired by a Stack Overflow thread (https://stackoverflow.com/questions/11648729/how-to-make-a-bash-spinner-animation). Let's get started!

Understanding the Code

The key to this animation is a combination of the spinner function and the echo command. Let's break it down:

spinner()
{
    local pid=$!
    local delay=0.75
    local spinstr='|/-\'
    while [ "$(ps a | awk '{print $1}' | grep $pid)" ]; do
        local temp=${spinstr#?}
        printf " [%c]  " "$spinstr"
        local spinstr=$temp${spinstr%"$temp"}
        sleep $delay
        printf "\b\b\b\b\b\b"
    done
}

sleep 5 & spinner | echo -e "\nCopyright of KatworX© Tech. Developed by Arjun Singh Kathait and Debugged by the ☆Stack Overflow Community☆"

Explanation:

1. spinner() Function:

   • This function is the core of the spinner animation. It takes care of the visual spinning effect.
   • local pid=$!: This line captures the process ID (PID) of the current function, which is essential for later checks to ensure the function is still running.
   • local delay=0.75: This defines the delay between each spin. You can adjust this value to control the animation speed.
   • local spinstr='|/-\': This string contains the characters used to create the spinning effect. You can customize this string for different visual styles.
   • The while loop checks if the function is still running using the ps command and the stored pid.
   • Within the loop, printf displays the current spinning character, and sleep introduces the delay.
   • printf "\b\b\b\b\b\b" clears the previous spin character from the terminal, creating the illusion of continuous spinning.

2. sleep 5 & spinner | echo -e ...:

   • This line runs the animation alongside the echo command.
   • sleep 5 &: This starts a background process that sleeps for 5 seconds. This is essential to ensure the spinner runs for the specified duration.
   • spinner: This calls the spinner function, starting the animation.
   • | echo -e ...: This pipes the output of spinner to the echo command, allowing the spinner to run while the copyright notice is being printed.

Additional Notes:

• Customizing the Spinner:
  • You can modify the spinstr variable in the spinner function to customize the appearance of the spinner. Try different characters or combinations for a unique look.
• Changing the Duration:
  • Adjust the sleep time in sleep 5 & ... to control how long the spinner runs.
• Using the Spinner in Other Scripts:
  • You can easily reuse the spinner function by defining it in your script or in a separate file that you can source.

Conclusion

By understanding this code and applying the tips given, you can add a simple yet effective spinner animation to your bash scripts. This will improve the user experience by providing visual feedback while your scripts are running. Remember to experiment with the code, customize it to your needs, and have fun with it!