> Also, the syntax is very heavy.  Was it inspired by another programming 
> language?  The ones I'm familiar with use $1, {1}, or similar syntax, but 
> I've never seen %1$s :/

From printf(3):

   By default, the arguments are used in the order given, …
   One can also specify explicitly which argument is taken, at each place
   where an argument is required, by writing "%m$" instead of '%' and "*m$"
   instead of '*', where the decimal integer m denotes the position in the
   argument list of the desired argument, indexed starting from 1.  Thus,

        printf("%*d", width, num);
        and
        printf("%2$*1$d", width, num);

https://en.wikipedia.org/wiki/Printf_format_string#Parameter_field

I don't know when POSIX introduced it, but it's been around for a while.