Many command line scripts simply read all the files mentioned to them as one long stream of data, the last file of one byte side by side with the first byte of the next file.  Ruby provides you with a very simple way to do this, by using the ARGF object combined with some simple option parsing.

What is truth?  No, not philosophically, in the (ironically imaginary) world of computer science, truth has a very well defined meaning.  But each high level language seems to interpret this a bit differently.  So what is truth in Ruby?  And how are they represented?

Exceptions, like just about everything else in Ruby, are objects.  They're objects you typically don't deal with either, in fact when you catch an exception using a rescue clause, you're often only testing for the presence of the exception an ignoring the exception object itself.  But there is slightly more you can do with them.

While the Bignum is not a class you'll encounter directly, you've probably used it a few times without even noticing it.  This article tells you a bit about how Bignum works and what you can do with it.