Is there some built in functionality in Vim to merge the contents of two registers into a single register by appending the two?

4 Answers 4


It is not exactly clear what you would like to happen when e.g. one register contains a linewise selection and the other one contains a block selection. But for the easy case, you can always do (as noted in a comment)

:let @c=@a.@b

and have the concatenation of register a and b in register c. But note, this might have funny effects, if the registers contain blockwise selections (or one register is of a different type than the other).

  • If not the registers contain blockwise selections? I'd edit, but I don't know what you meant to say.
    – Wildcard
    Sep 6, 2017 at 20:58
  • This is close enough to what I wanted. I forgot to mention it in my OP, but my goal is to make it so that I can copy string after string and produce a long string consisting of all copied parts. In my case it is to yank the BibTeX keys from the bibliography file into a single LaTeX citation like so: \cite{smith2015,knuth1999,lindhe2016}.
    – lindhe
    Sep 14, 2017 at 14:57

Let's say you want to merge "a and "b into "c:

call setreg('c', getreg('a').getreg('b'))

You can of course replace a, b and c by whatever register you want.

For a bit more of details:

getreg('x') will return the content of the register x as a string.

In vim you can concatenate two strings with . like this:

let str1 = 'foo'
let str2 = 'bar'
let result = str1 . str2
" result is equal to 'foobar'

Thus getreg('a').getreg('b') concatenate the content of registers "a and "b.

Finally setreg() allows you set the content of a register.

See the doc for more details:

  • 2
    Another way to do this would be: :let @c = @a . @b.
    – garyjohn
    Sep 6, 2017 at 15:06
  • @garyjohn Ahah yes that is much easier! Using setreg became an automatism for me because I often had problems with let @... but most of the time these problems were related to the registers types so here it is not really a good argument.
    – statox
    Sep 6, 2017 at 15:43

When registers only contain strings, we can do it with the old

:let @c = @a . @b

If you want to handle the registers as lists (one element per line), then you'll need to use the new functions described by @statox, but beware, lists are concatenated with +, not ..

:call setreg('c', getreg('a', 1, 1) + getreg('b', 1, 1))

Additionally and as an alternative:
if you only want to append something onto an allready filled register,
you can use the "uppercase-version" of the register-name.

For example:

  • you're marking a line of text with shift+v,
  • you'r "yanking" that text into register @a with shift+", a, y
  • next you're marking another line of text ...
  • and this one, you're appending onto register @a with shift+", A, y

As result you have two lines of text in register @a.

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