Delete blank lines within range

Question

Suppose I have the file:

begin
asdf

asdf
end

begin

asdf
end

begin
asdfasdf

end

How can I use something like the global command to delete every empty line in between 'begin' and 'end'?

:/begin/,/end/ g/^$/d only deletes the space in the first begin/end block.

Thank you for your help!

Answer 1

In the very general case, the :g command cannot be called recursively. There is one exception: Since Vim patch 8.0.0630, one can call a recursive :g command, if it operates only within a single line. So you can do something like (quoting the help):

When the command is used recursively, it only works on one line. Giving a range is then not allowed. This is useful to find all lines that match a pattern and do not match another pattern:

    :g/found/v/notfound/{cmd}

This first finds all lines containing "found", but only executes {cmd} when there is no match for "notfound".

However that means, this does not apply to your use case here. You would need to call :g to mark all begin/end regions, and then call another :g command to find empty lines (to be deleted).

However, in your case, you can use the :s command like this:

g/begin/,/end/s/^\n//

Note: We are searching for line start (^), followed by a line break (\n), because we want to remove this line break, effectively deleting the empty line. For that reason using the pattern ^$ to the :s command would not work, as it would leave the empty line intact (keep the line break).

Answer 2

You could instead try this: :g/begin/,/end/ s/^$//. I don't think g works recursively, so using s instead seems to do the job.