Shell Programming and Scripting

#!/bin/bash
count=1
var1="00100011"
while [[ $count -le ${#var1} ]]
do
     var2=$(expr substr $var1 $count 1)
     if [ "$var2" -eq 1 ];
        then
        var3=0
     else
        var3=1
        echo $var3
        count=`expr $count + 1`
     fi
     done

echo "$var1" | sed 's 0 - g; s 1 0 g; s - 1 g'

#!/bin/bash
count=1
var1="00100011"
printf " Original: $var1\n"
printf " Inverted: "
while [[ $count -le ${#var1} ]]
do
  var2=$(expr substr $var1 $count 1)
  if [ "$var2" -eq 1 ];
  then
    var3=0
  else
    var3=1
  fi
  # echo $var3
  printf $var3
  count=`expr $count + 1`
done
printf "\n"

 Original: 00100011
 Inverted: 11011100

tr 01 10

echo 101101 | sed 'y/01/10/'
010010