After looking into Fink Command and Porticus I could not find the GNU command ‘tac’ for writing bash scripts.
So I found these replacements which works well from the following link (Thanks guys :-))
http://trac.osgeo.org/grass/ticket/181
Normal use of tac: .....| tac |.......
Replacement Nr. 1
.....| awk '{print NR,$0}' | sort -nr | sed 's/^[0-9]* //' | .......
Replacement Nr. 2
tac () {
awk '1 { last = NR; line[last] = $0; } END { for (i = last; i > 0; i--) { print line[i]; } }'
}