Replace one substring for another string in shell script

Question

I have \"I love Suzi and Marry\" and I want to change \"Suzi\" to \"Sara\".

#!/bin/bash
firstString=\"I love Suzi and Marry\"
secondString=\"Sara\"
# do some         


        

Answer 1

I know this is old but since no one mentioned about using awk:

    firstString="I love Suzi and Marry"
    echo $firstString | awk '{gsub("Suzi","Sara"); print}'