Update: Just as I was about to post this, I figured out my own answer, using a lookahead: /(?=aa)./. The lookahead matches without advancing pos, the "." advances pos by 1. Are there other ways to do this? More efficient ways?

You don't need the dot:

    my $str= "aaa aa aaa";
    print "String = '$str'\n";
    while(  $str =~ /(?=aa)/g  ) {
        print pos($str), $/;
    }
__END__
String = 'aaa aa aaa'
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See RE: Re: ^x* vs x*$ for why.

                - tye ("Twice in one day")