How to create a rotation animation using shell script?

I am looking for a script that creates a rotation animation using character /,-, | and \.

If you continuously switch between these characters it should look like its rotating. How to make this?

Use that script:

#!/bin/bash

chars="/-\|"

while :; do
  for (( i=0; i<${#chars}; i++ )); do
    sleep 0.5
    echo -en "${chars:$i:1}" "\r"
  done
done

The while loop runs infinite. The for loop runs trough each character of the string given in $chars. echo prints the character, with a carriage return \r, but without linebreak -n. -e forces echo to interpret escape sequences such as \r. There's a delay of 0.5 seconds between each change.

Here's an example using \b, which tells the terminal emulator to move the cursor one column to the left, in order to keep overwriting the same character over and over.

#!/usr/bin/env bash

spinner() {
    local i sp n
    sp='/-\|'
    n=${#sp}
    printf ' '
    while sleep 0.1; do
        printf "%s\b" "${sp:i++%n:1}"
    done
}

printf 'Doing important work '
spinner &

sleep 10  # sleeping for 10 seconds is important work

kill "$!" # kill the spinner
printf '\n'

See BashFAQ 34 for more.

Since you don't explicitly ask for bash, a little plug for the fish shell, where this can be solved beautifully IMO:

set -l symbols ◷ ◶ ◵ ◴
while sleep 0.5
    echo -e -n "\b$symbols[1]"
    set -l symbols $symbols[2..-1] $symbols[1]
end

In this case, symbols is an array variable, and the contents if it are rotated/shifted, because $symbols[2..-1] are all entries but the first.

How to create a rotation animation using shell script?

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