The problemSome files have a lot of empty lines.
You may want to condense multiple empty lines to a single empty line.
You may want to get rid of all empty lines.
cat -s filename condenses multiple empty lines to a single empty line.
Inside vim, call the command as :%!cat -s
cat -s filename | sed '/^$/d' gets rid of all empty lines.
Inside vim, call the command as :%!cat -s | sed '/^$/d'
Empty lines are not the same as blank lines.
Empty lines have nothing in them.
Blank lines may have spaces and tabs that you can't see.
These commands won't work with tabs or spaces on an "empty" line.