bash实现动态进度条

#!/bin/bash
i=0
bar=''
index=0
arr=( "|" "/" "-" "\\\\" )

while [ $i -le 100 ]
do
    let index=index%4
    printf "[%-100s][%d%%][\\e[43;46;1m%c\\e[0m]\\r" "$bar" "$i" "${arr[$index]}"
    let i++
    let index++
    usleep 30000
    bar+='#'
    clear
done

printf "\\n"