unix script for parsing the table:

 1,2,3,4,5,6,7,8,0,0,0,0

 0,1,2,3,4,5,6,7,8,0,0,0

 0,0,1,2,3,4,5,6,7,8,0,0

 0,0,0,1,2,3,4,5,6,7,8,0

 0,0,0,0,1,2,3,4,5,6,7,8

display:

start r2 c4

end   r5 c4

start r2 c6

end r5 c6

start r2 c8

end r5 c8

command: cat a.txt |awk -F "," 'NR>=2 && NR <=5'|awk -F "," '{print $4" "$6" "$8;}'

result:

3 5 7

2 4 6

1 3 5

0 2 4