Below is a simple bash script which will find and replace the substring withing the string. Feel free to use or modify this script.
Source: cat stringreplace.sh
#!/bin/bash
echo -n "Enter main string: "
read string
echo -n "Enter the sub-string that you want to replace: "
read old
echo -n "Enter new sub-string that you want to replace with: "
read new
echo "The new string is now: ${string/$old/$new}"
#!/bin/bash
echo -n "Enter main string: "
read string
echo -n "Enter the sub-string that you want to replace: "
read old
echo -n "Enter new sub-string that you want to replace with: "
read new
echo "The new string is now: ${string/$old/$new}"
Result: ./stringreplace.sh
Enter main string: linuxpoison
Enter the sub-string that you want to replace: poison
Enter new sub-string that you want to replace with: os
The new string is now: linuxos
source:http://linuxpoison.blogspot.com/2012/06/135781677513196.html