# print all lines
sed -n -e 'p' < file

# print the first 10 lines
sed -e '10q' < file
sed -n -e '1,10p' < file

# print lines 81 to 100
sed -n -e '81,100p' < file

# print the last 10 lines of the file?
sed -n -e '$-10,$p' < file  # does NOT work