Howdy Coolguy, (I wish I could be a cool guy ;) )
When you enter find mode, look below the find button on the toolbar, (FMP8-9) and you'll see dropdown list of operators. Among them is "=" which is what you're looking for.
"=" (without the quotes) means "Exact Match", so you would enter find mode, then type "=sha" to find those records that have "Sha", but not "Shamus" or "Shallot".
This is what you're after, no?
How can i do the exact matching using script?
Enter Find Mode
Setfield [ Yourfield ; "=" & ITEM ]
I have used "ITEM" to represent a variable or constant, whatever is applicable. If it is text constant (like "sha"), you could simplify by using:
SetField [ Yourfield ; "=sha" ].
If it is a variable that you set earlier in the script, you would use:
SetField [Yourfield ; "=" & $variable ]