You use the \u/\U and \l/\L operators in conjunction with a regex. \u uppercases the next character, \U to all following characters. Likewise with \l, except for lower-case. You can stack them too, like \u\L, which will make the next character upper-case, but all subsequent ones lower-case. 
$_ = "";
s/\b(\w+)\b/\u\L$1/g;
s/(\w+\s*)$/\U$1/g;

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Thus, "tHis is a TEST line oF,teXT" will become "This Is A Test Line Of,TEXT". If you have a lot of debris, like brackets, commas and whatnot, you might have to tweak this a bit to better match your definition of "word". Do you want it to be "Free-Lance" or "Free-lance"?

In reply to Re: Mixing the case of a line by tadman
in thread Mixing the case of a line by Joes

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