How can I replace multiple empty lines with a single empty line in bash?

Question

I have a file that contains:

something



something else

something else again

I need a bash command, sed/grep w.e that will produce the fo

Answer 1

grep -A1 .  | grep -v "^--$"

This grep solution works assuming you want the following:

Input

line1

line2
line3


line4



line5

Output

line1

line2
line3

line4

line5