I'd disagree and say it's marginally off topic. Having a strong C background made picking up Perl a snap, and it's a very good thing to have to understand the *NIX / POSIX underpinnings which Perl sits on top of. Not to mention if you ever want to interact with external libraries via XS or Inline::C.

On the other hand, having a strong C background makes you program perl as if it were C. When I'm recruiting for perl people, I ask that applicants be competent with some other language, but I don't care what language.

That said, I'll second both K&R (2nd edition) and The Joy Of C. Both are very good.

I agree that a systems programming language like C would complement Perl well; small overlap in their problem areas.

(Strictly commercially today, Java might be a better choice. I don't know.)

If you are going to learn C, I would recommend spending a few hours looking over processor architecture, if you don't know anything about it. C is quite close to the machine and it is enlightening to think about how C code would compile.

I am impressed by your will to learn. I know fewer languages after learning Perl! I stopped using AWK, shell and others and can't say I know them anymore. I know a better superset.

My favorite C book is Harbinson-Steele, but it is not that relevant anymore. Go with K&R or some other recommendation.