Making animated text in linux terminal

Question

I would like to make animated text inside of the Linux terminal.

By 'animated', I mean a single character constantly changing to make it form some sort of animation. What I want is something like this:

|  # First second
/  # One second after previous frame
-  # One second after previous frame
|  # One second after previous frame
-  # One second after previous frame
\  # Last frame, skip back to top

...so it creates a line that appears to be spinning.

I am already quite aware of the method using clear, however this does not suit my needs.

clear removes all text, including previous text. I do not want this. I have seen plenty of animations in the terminal window not doing this (for example the loading bar shown using apt install), however, I have failed to reproduce.

How would I make an animation, such as a loading bar using the Linux terminal? If a library, I would prefer it being C++.

Answer 1

Using tput is the key here which is part of ncurses.

This is the sample script which I wrote:-

#!/usr/bin/env bash

clear  # Let clear the screen first

echo " Starting the spinning wheel.."
echo " Press 'q' or 'Q' to stop it.."

# to set the cursor position on terminal on row 2 column 1
tput cup 2 1

while true; do
   echo '|'
   sleep 1
   tput cup 2 1  # reset cursor position

   echo '/'
   sleep 1
   tput cup 2 1  # reset cursor position
   echo '-'

   sleep 1
   tput cup 2 1  # reset cursor position
   echo '\'

   sleep 1
   tput cup 2 1  # reset cursor position
   echo '|'

   tput cup 2 1  # reset cursor position
  # -t for timeout, -N to except only 1 character
   read -t 0.25 -N 1 ch
   if [[ $ch = "q" ]] || [[ $ch = "Q" ]]; then
       # The following line is for the prompt to appear on a new line.
        echo
        break
   fi

done

It's like a basic version. You can refine it further. You can find the script here as well:- https://github.com/uv3003/uv/blob/main/rolling_pointer.sh

Regards, Yuvraj