Quick and dirty progress bar function in shell

progress.sh

#!/bin/sh

print_progress_bar(){
    percent=$1
    width=$2
    width=$(( ${width} - 10 ))
    barlen=$(( ${width} * ${percent} / 100 ))
    voidlen=$(( ${width} - ${barlen} ))
    bar=`printf %${barlen}s |tr " " "="`
    void=`printf %${voidlen}s`
    if [ `printf ${percent} | wc -c` -eq 1 ]
    then
        percent=" ${percent}"
    fi
    printf "\r[${bar}${void}] (${percent}%%)"
}

counter=0
while [ $counter -ne 101 ]
do
        print_progress_bar ${counter} 80
        counter=$(( $counter + 1  ))
        sleep 0.1
done