Your problem is that $1...$3 are not indices in an array, but are read-only scalar variables generated by the system. Thus, $1 is not at all the same as $[1] (heh, heh) or something like that.

You want to use eval() to convert your iterator into something usable, like so:

perl -e "$a = qq(foo); $a =~ m/(foo)/; $s = 1; $xx =  eval('\$$s');pri
+nt $$xx; "
[download]

Celebrate Intellectual Diversity