Oh I always do ctrl+shift+r for that last bit, like reverse-tabbing on a gui. Good to know about ctrl+s, though I imagine muscle memory will prevent me for ever using it. :)
normally control-shift-r is just control-r; both key combinations send the same byte, 0x12, so they both search backwards in readline history. is your terminal emulator doing something different? if you type control-v control-shift-r enter control-d as the input to the command od -t x1a, what does it say?
