Find and Replace in Shell/Bash Scripts

We can do this Find and Replace task in Scripts using vi/vim editors.

Open your Script with vi/vim editor, then
:%s/WordToReplace/ReplaceWith/g

Finding and Replacing a word with Confirmation
:%s/WordToReplace/ReplaceWith/gc

Case Insenitive Finding and Replacing
:%s/OLD/new/gi
This will find all the words "Old, OLd,olD..." and Replaces with word "new"

Case Insensitive Find and Replace
:%s/OLD/new/gI

Find and Replace between L1 and L2 lines
:L1,L2s/OLD/new/g

Finding and Replacing only specific word

:%s/\<OLD\>/new/gc