ref: ba4a1c07f1bc7622f8a3dcd4f2d383f4ec70fc1c dir: /test/t.split3/
{ a = $0 " " $0 " " $0 if ($1 != "") n = split (a, x, "[" $1 "]") print n, x[1], x[2], x[3], x[4] }