LeftPad in Shell (Bash)

#!/bin/bash
leftPad() {
  SIZE=${#1}
  PADCHAR="."
  if [ ! -z $3 ]; then
    PADCHAR=$3
  fi
  PAD=$(($2 - SIZE))
  COUNTER=0
  RESULT=""
  while [  $COUNTER -lt $PAD ]; do
    RESULT="$RESULT$PADCHAR"
    let COUNTER=COUNTER+1
  done
  RESULT="$RESULT$1"
  echo $RESULT
}
leftPad "foo" 6 "."
leftPad "1" 1
leftPad "2" 2
leftPad "3" 3
leftPad "4" 4
leftPad "5" 5
leftPad "hello" 7
leftPad "foo" 6
leftPad "foo" 3
leftPad "foobar" 3
leftPad "foo" 6 "?"