The -s option in cat turns multiple consecutive blank lines into one blank line.
$ echo -e "hello\n\n\n\n\n\n\n\n\n\nworld" > hello.txt $ cat -s hello.txt hello world It's not directly customizable, but it could make it a little easier to organize your text. For instance, you could run the file through cat -s first and then change every blank line into something else:
$ cat -s hello.txt | sed "s/^[[:space:]]*$/...\n . \n.../g" hello ... . ... world