Crash IRB (interactive Ruby) Ruby comes with a built-in REPL, which is quite handy.



Your challenge is to crash it in the least amount of code!

The definition of "crash" is "make it exit in an unintended way." This means exit, quit, abort, irb_exit, irb_quit, et. al. are not valid answers.

Furthermore, you may not cause any side-effect to any other part of the system. For example, `rm -rf /` is not valid either.

Any version 1.9.3 or above is valid. If your code only works on a specific version of Ruby, you may specify that in the answer.

The final restriction is that you may not rely on any gems.

This is code-golf, so the shortest code that crashes IRB will win!
16 characters

String=0
String=0


Not the shortest, but I think it's funny that it doesn't crash until the second line. Generates roughly 20 lines of text before IRB exits. For some reason it cannot be shortened to for instance 2.times{String=0}.



edit

Of all the answers so far, this is the only one that has worked for me (and it works in all versions I could get my hands on), and I've tested all of them in these versions:

On whatever kind of Linux I get when ssh'ing into my university:

ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-linux]
ruby 1.8.5 (2006-08-25) [x86_64-linux]


Mac OS X Mavericks default:

ruby 2.0.0p247 (2013-06-27 revision 41674) [universal.x86_64-darwin13]


Installed through Homebrew on OS X:

ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-darwin12.4.0]




edit 2

7 characters

Combining my first version (and/or @Howard's answer, for maximum cross reference) with @chinese perl goth's answer:

STDIN=0