How to add a progress bar to a shell script?

Question

When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.

For example, copying a b

Answer 1

#!/bin/bash

function progress_bar() {
    bar=""
    total=10
    [[ -z $1 ]] && input=0 || input=${1}
    x="##"
   for i in `seq 1 10`; do
        if [ $i -le $input ] ;then
            bar=$bar$x
        else
            bar="$bar  "
       fi
    done
    #pct=$((200*$input/$total % 2 + 100*$input/$total))
    pct=$(($input*10))
    echo -ne "Progress : [ ${bar} ] (${pct}%) \r"    
    sleep 1
    if [ $input -eq 10 ] ;then
        echo -ne '\n'
    fi

}

could create a function that draws this on a scale say 1-10 for the number of bars :

progress_bar 1
echo "doing something ..."
progress_bar 2
echo "doing something ..."
progress_bar 3
echo "doing something ..."
progress_bar 8
echo "doing something ..."
progress_bar 10