Remove duplicate empty lines using sed

Content

Use sed to remove duplicate empty lines from a file and replace them with a single empty line.

remove_duplicate_empty_lines() {     sed '/^$/N;/^\n$/D' } sed -i "" '/^$/N;/^\n$/D' input.txt

Example:

$ cat --number file.txt      1    1      2      3      4      5    5      6    6      7      8      9    9   $ cat file.txt | sed '/^$/N;/^\n$/D' > modified.txt   $ cat --number modified.txt      1    1      2      3    5      4    6      5      6    9