Write the top to file and sed

top -b -n 30 -d 1 > top_out

# -b is batch mode
#-n is the 30 runs
# -d is 1 second to write

# out the fille
sed -n 100p top_out

or 

sed -n "100,$ p" test_out



# Ref
http://linux.vbird.org/linux_basic/0440processcontrol/0440processcontrol-fc4.php