bash - unix sed command does not work -

i'm trying edit file called bookdb.txt contains

boy:man:67.00:15:28  harry potter - order of phoenix:j.k.rowling:70.00:40:20 harry potter - half blood prince:j.k.rowling:40.00:50:20

this command

sed -i "s/""$title""/""$newtitle""/g" ./bookdb.txt

it works. want make sure edits exact string of $title, because if lets contains "a", letter in file changed. how use <\ \> in case ?

a simple option try, since title begins @ beginning of line , delimited colon, this:

sed -i "s/^""$title:/""$newtitle"":/g" bookdb.txt

note ^ anchors match beginning of line, , : in both match , replacement section.

Camp