How to join lines without producing a space?

Question

The standard J command for joining lines replaces the newline character(s) with a space. It's useful when editing 'literature' but can be troublesome if I, say, edit a hex dump by hand if I forget to remove the superfluous space.

Is there a quick & easy method to join two lines without producing a space between them?

Answer 1

The gJ mapping does this; from :help gJ:

Join [count] lines, with a minimum of two lines. Don't insert or remove any spaces.

You could rebind it to J, if you want to save a keystroke:

:nnoremap J gJ

Note that this doesn't remove any spaces, so if either the current line ends with a space or next line starts with one or more spaces they will be left as is; so this:

Hello
    world

Becomes:

Hello    world

We could use Jx in this case, then it will be Helloworld, but that won't work in all cases; from the help:

Join the highlighted lines, with a minimum of two lines. Remove the indent and insert up to two spaces

[...]

These commands, except "gJ", insert one space in place of the unless there is trailing white space or the next line starts with a ')'.

So in some cases more than one space or no space is inserted. As far as I can see, there is no easy way to change this behaviour; I created a function to modify gJ to always join without spaces:

" Like gJ, but always remove spaces
fun! s:join_spaceless()
    execute 'normal! gJ'

    " Remove character under the cursor if it's whitespace.
    if matchstr(getline('.'), '\%' . col('.') . 'c.') =~ '\s'
        execute 'normal! dw'
    endif
endfun

" Map it to a key
nnoremap <Leader>J :call <SID>join_spaceless()<CR>

If you want, you can add let save = winsaveview() at the start of the function, and call winrestview(save) at the end to prevent the cursor from moving (but the current behaviour is the same as gJ).

See also: :help J, :help 'joinspaces'

Answer 2

Another trick you may try is to use replace. Sometimes this might be useful.

%s/$\n//g

Scenario: Delete the last character and join with the next line:

%s/=$\n\(.\)/\1/g

For example,

xxxx=
123

becomes:

xxxx123

Answer 3

To always join with a single space :

nmap J gJi <ESC>ciW <ESC>

To join with no space at all (removes trailing+leading space) :

nmap <C-J> gJi <ESC>diW

Answer 4

Create a macro and reuse it:

qaJxq

Now replay the macro, a by using @a wherever you want to join two lines with no space.

@@ will repeat the previous macro. So you can just hold @ to join multiple lines.

Answer 5

Select the lines you'd like to merge, enter an Ex command by typing a colon : in normal mode. Then type this command:

s/$\n\s*//gc

The entire command should look likewise:

:'<,'>s/$\n\s*//gc

This is actually a tweaked version of the @insidepower's command that replaces space-indentations as well as newline characters.

Explanation:

• '<,'> means that we modify only the lines selected in visual mode.

• /$\n\s* is a regex pattern. We're looking for a match that ends $ with a new line character \n and has non-determined number of whitespaces * thereafter.

• s/pattern//gc is a substitute command to find each pattern and replace it with an empty character on confirmation.

To figure out more about flags and metacharacters for regular expressions in Vim take a look at this chapter of Vim Reference.