if -ge =greater /equal
-le = less/ equal

what if we want just equal
i cannot used (=)

eg:
if [ $file_year = $curr_year ]
echo "..."
fi

if [ $file_year = $curr_year + 1 ]--> this comparison also wrong
echo"...
else
echo"....
fi

-eq - equal
-ge - greater or equal
-le - lesser or equal
-lt - less than
-gt - greater than
-ne - not equal

it really help me...