You can search bash's history using what you have already typed easily.
Suppose you have just typed
curl -I http://superuser.com and you forgot to type Ctrl+r first:
$ curl -I http://superuser.com
If you want to do an i-search on your history, go to the beginning of line first (Ctrl+a), enter i-search (Ctrl+r) and type Ctrl+y. This should search using the contents of the whole text you already typed:
(reverse-i-search)`curl -I http://superuser.com': curl -I http://superuser.com/faq
Alternatively, you can use Ctrl+w instead of Ctrl+y to search using just the first word of the text you just typed:
(reverse-i-search)`curl': curl -I http://superuser.com/faq
Binding it all to a single key
If you want to do all this in one keystroke, you can bind a single key to a keyboard macro. If you want to use, say, F12 run:
$ bind '"\e[24~":"\C-a\C-r\C-y"'
That will last for the session.
Making it permanent
Just define the macro in your
Note that here we omit the single quotes.
You might find this answer useful.