ref: 5086f3453d6716d6dcd782a45831c1ebb0f2b115 dir: /test/t.set0/
{$0 = $1; print; print NF, $0; print $2} {$(0) = $1; print; print NF, $0; print $2} { i = 1; $(i) = $i+1; print }