Learning C

I recently made a few C++ program for my course and it reignited my interest in programming (I had previously done a little C) and I'd like to learn properly in my spare time, I'm interested in making small programs that perform useful tasks or automate menial ones but ultimately I'd like to be able to make a nice looking tag based file database that will allow me to thoroughly categorize things as the current options are quite lacking in features. Obviously that's a while away yet and I'm sure to think of more things before then.

I think C is the right choice because it seems to be very multi-purpose and there is a lot of documentation on it, so much in fact I don't really know where to start. I know K&R is a popular book but the last edition was released 22 years ago and I'm sure that many things have changed since then, is there perhaps a more modern one that I should be looking at [after/instead of] K&R?

ultimately I'd like to be able to make a nice looking tag based file database that will allow me to thoroughly categorize things as the current options are quite lacking in features.
Do it in Ruby on Rails, watch the screencasts!