spinner.sh

#!/bin/bash

spinner() {
  local i sp n
  sp='/-\|'
  n=${#sp}
  printf ' '
  while sleep 0.1; do
    printf "%s\b" "${sp:i++%n:1}"
  done
}
main() {
  spinner &
  spinner_pid=$!
  
  # do something here
   
  kill $spinner_pid
  wait $spinner_pid 2>/dev/null
  
  # done
}
main "$@"