Welcome maheshkumar,

Two things you may want to search on:

• "Slurp a file" or reading the entire file into a string in memory. I use 'read' or 'sysread', but there are other techniques.
  
  
• 'index' function to find exact location of sub-strings

If the file is larger than available memory, you can use the 'read' or 'sysread' in a loop, getting chucks of the file that will fit in available memory. This may be more complicated, but you don't have to worry about line endings.

Good Luck!