Bash Shell Quick If Then and Case Switch Statements

protocol=udp # or tcp

# If-then implementation
if [$protocol == udp]
then
	prefix=@
else
	prefix=@@
fi
  
# Case-switch implementation
case "$protocol" in 
    #case 1
    "udp") prefix=@ ;; 
    #case 2
    "tcp") prefix=@@ ;; 
    #case 3 
    "") prefix=@@ ;; 
esac

echo "$prefix"