[newbie] constructing a discrete dataset

[Jean Dubois]

I'd like to generate every possible combination a b c d e f for three
possible values (1, 2, 3) of each variable
Something which starts like this:
1 1 1 1 1 1
1 1 1 1 1 2
1 1 1 1 1 3
1 1 1 1 2 1
1 1 1 1 2 2
1 1 1 1 2 3
1 1 1 1 3 1
1 1 1 1 3 2
1 1 1 1 3 3
1 1 1 2 1 1
1 1 1 2 1 2
1 1 1 2 1 3
1 1 1 2 2 1
1 1 1 2 2 2
1 1 1 2 2 3
1 1 1 2 3 1
1 1 1 2 3 2
1 1 1 2 3 3
.
.
.
Can anyone here suggest how this is best done in octave in a time
efficient manner (I suppose nested for-loops are a bad idea)?

thanks in advance
jean