search file content

I want to perform search by content in a file using the Finder’s find or Sherlock. For instance I would like to search for a specific string in FrameMaker file.
I am running system X 10.2.x
How can I do it?

Thanks for the help.

If you are looking for a single string in a single file, you can use this code:

if (offset of "some text" in (read alias "path:to:file.txt")) = 0 then
	display dialog "Not found!"
else
	display dialog "Found!"
end if