Delete \n characters from line range in text file

Question

Let\'s say we have a text file with 1000 lines.

How can we delete new line characters from line 20 to 500 (replace them with space for example)?

My try:

Answer 1

This might work for you (GNU sed):

sed -r '20,500{N;s/^(.*)(\n)/\2\1 /;D}' file

or perhaps more readably:

sed ':a;20,500{N;s/\n/ /;ta}' file