0~⍨⍎⍞~'[]'

s;[^0-9]+0|[],[]+;;g

bash-3.2$ sed -rf sedFile <<< "[[[4, 5, 8]], [[5, 6, 20]], [[1, 20, 500]]]"
4 5 8 5 6 20 1 20 500

s/[^0-9][^1-9]*/ /g

perl -ple 's/D+0?/ /g'

perl -E '$,=$";sub p{map{ref$_?p(@$_):$_||""}@_}say p eval<>'

def d(x):
 try:map(d,x)
 except:print`x`*(x!=0)

{x@?&x:,//x}

k){x@?&x:,//x}((1;0);(2;0);(2;3))
1 2 2 3
k){x@?&x:,//x}(((4;5;8));((5;6;20));((1;20;500)))
4 5 8 5 6 20 1 20 500
k){x@?&x:,//x}(((1;0);(0;0);(0;0));((1;0);(1;2);(2;0));((2;0);(0;0);(0;0)))
1 1 1 2 2 2

s/D+|b0/ /g

cat '[[1, 0], [2, 0], [2, 3]]' | perl -pe 's/D+|b0/ /g'

puts eval(gets).flatten.reject &:zero?

~{[]*}4*{},' '*

echo [[[1 0] [0 0] [0 0]] [[1 0] [1 2] [2 0]] [[2 0] [0 0] [0 0]]] | ruby golfscript.rb x.gs

1 1 1 2 2 2

import re
print(*re.findall('[1-9]d*',input()))

import re
print re.sub('D[^1-9]*',' ',raw_input())[1:-1]

for(;s=strtok(s,"[], ");s=0)atoi(s)&&puts(s);

def d(l):
    if list==type(l):return[y for x in l for y in d(x)]
    return[str(l)]*(l!=0)
print" ".join(d(input()))

d=lambda l:list==type(l)and[y for x in l for y in d(x)]or[str(l)]*(l!=0)
print" ".join(d(input()))

print(readLine split"\D|\b0"mkString" ")

x([H|T]):-x(H),x(T).
x(0). x([]).
x(M):-write(M),put(32).
:-read(X),x(X),halt.

def f[A](l:List[_]):List[_]=l match{
case Nil=>l
case(l:List[_])::s=>(f(l):::f(s))
case e::s=>e::f(s)}
def p(l:List[_])=f(l)filter(!=0)mkString " "

val l1 = List (List (1, 0), List (2, 0), List (2, 3))
val l2 = List (List (List (4, 5, 8)), List (List (5, 6, 20)), List (List (1, 20, 500)))
val l3 = List (List (List (1, 0), List (0, 0), List (0, 0)), List (List (1, 0), List (1, 2), List (2, 0)), List (List (2, 0), List (0, 0), List (0, 0)))
val l4 = List (l1, l2, l3)

scala> l4.map(p)
res94: List[String] = List(1 2 2 3, 4 5 8 5 6 20 1 20 500, 1 1 1 2 2 2)

scala> p(l4)
res95: String = 1 2 2 3 4 5 8 5 6 20 1 20 500 1 1 1 2 2 2

l=$(echo "[[[1, 0], [0, 0], [0, 0]], [[1, 0], [1, 2], [2, 0]], [[2, 0], [0, 0], [0, 0]]]")
echo $l|tr -d '][,'|sed 's/b0b/ /g'
1           1   1 2 2   2

1    2    2 3
   4 5 8   5 6 20   1 20 500
   1               1    1 2  2     2