sed -n 'np' filename
Second n is the line number of the filename;
For example, if you want to print the second line of filename, you can run
sed -n '2p' filename
sed -n 'x,yp' filename
This command will output content of filename between line x and line y.
For example, if you want to print content between line 3 to line 10, you can run
sed -n '3,10p' filename
