How do I capitalize all the words on one line?

        $line =~ s/\b(\w)/\U$1/g;

This has the strange effect of turning ``don't do it'' into ``Don'T Do It''. Sometimes you might want this, instead (Suggested by Brian Foy <comdog@computerdog.com>):

    $string =~ s/ (
                 (^\w)    #at the beginning of the line
                   |      # or
                 (\s\w)   #preceded by whitespace
                   )
                /\U$1/xg;
    $string =~ /([\w']+)/\u\L$1/g;

To make the whole line upper case:

        $line = uc($line);

To force each word to be lower case, with the first letter upper case:

        $line =~ s/(\w+)/\u\L$1/g;