readline missing history-search-{backward,forward}

Well, you have managed to find a feature/config I didn't even know about...kudos!

So you are saying that the given config file does have an effect on readline behavior, but doesn't do what it's supposed to, right? I'm not familiar with .inputrc at all...is this something processed by IRB? Will investigate a bit. If you can do some investigation as well it would accelerate fixing this issue.

Ahh, ok, so .inputrc is a bash thing, and you're rebinding up and down to bash commands history-search-forward and history-search-backward. Does this affect MRI's IRB the way you would expect?

Yes. MRI IRB with such .inputrc behaves exactly the same as in bash.

Hmm. So the equivalent keystroke in readline would be C-r, which does appear to work ok in jirb:

system ~/projects/jruby $ jirb
irb(main):001:0> puts 'hello'
hello
=> nil
irb(main):002:0> # next line will use C-r
irb(main):003:0* puts 'hello'
hello
=> nil
(reverse-i-search)`put': puts 'hello'

It seems like C-r works on its own, but however up/down get rebound by bash breaks on our readline implementation (jline).

I'm going to file this as an issue with jline for now.

Filed: https://github.com/jline/jline2/issues/51

Someone came up with a fix for the backward search but jline does not yet support forward search. We'll need a jline release to pick up the change.