Vim registers: The basics and beyond


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Vim’s registers are that kind of stuff that you don’t think you need until you learn about them. After that, they become essential in your workflow, and it’s hard to let them behind. Saying that, it’s still incredible how many people use vim for years without knowing how to make proper use of them. Bear with me and you won’t be one of them.

If you have no idea what I’m talking about

You can think of registers as a bunch of spaces in memory that vim uses to store some text. Each of these spaces has a identifier, so it can be accessed later.
It’s no different than when you copy some text to your clipboard, except that you usually have just one clipboard to copy to, while vim allows you to have multiple places to store different texts.

The basic usage

Every register is accessed using a double quote before its name. For example, we can access the content that is in the register r with "r.

You could add the selected text to the register r by doing "ry. By doing y you are copying (yanking) the selected text, and then adding it to the register "r. To paste the content of this register, the logic is the same: "rp. You are pasting the data that is in this register.
You can also access the registers in insert/command mode with Ctrl-r + register name, like in Ctrl-r r. It will just paste the text in your current buffer.
You can use the :reg command to see all the registers and their content, or filter just the ones that you are interested with :reg a b c.

:reg a b c
--- Registers ---
"a   register a content
"b   register b content
"c   register c content

The unnamed register

vim has a unnamed (or default) register that can be accessed with "". Any text that you delete (with d, c, s or x) or yank (with y) will be placed there, and that’s what vim uses to paste, when no explicit register is given. A simple p is the same thing as doing ""p.

Never lose a yanked text again

It already happened to all of us. We yank some text, than delete some other, and when we try to paste the yanked text, it’s not there anymore, vim replaced it with the text that you deleted, then you need to go there and yanked that text again.
Well, as I said, vim will always replace the unnamed register, but of course we didn’t lose the yanked text, vim would not have survived that long if it was that dumb, right?

vim automatically populates what is called the numbered registers for us. As expected, these are registers from "0 to "9.
"0 will always have the content of the latest yank, and the others will have last 9 deleted text, being "1 the newest, and "9 the oldest. So if you yanked some text, you can always refer to it using "0p.

The read only registers

There are 4 read only registers: "., "%, ": and "#
The last inserted text is stored on "., and it’s quite handy if you need to write the same text twice, in different places, not needing to yank and paste.

"% has the current file path, starting from the directory where vim was first opened. What I usually use it for is to copy the current file to the clipboard, so I can use it externally (running a script in another terminal, for instance). You could execute :let @+=@% to do that. let is used to write to a register, and "+ is the clipboard register, so we are copying the current file path to the clipboard.

": is the most recently executed command. If you save the current buffer with :w, “w” will be in this register. A good way to use it is with @:, to execute this command again. For example, if you execute a substitute command in one line, like in :s/foo/bar, you can just to go another line and execute @: to run this substitution again.

"# is the name of the alternate file, that you can think of it as the last edited file (it’s a bit more complex than that, go to :h alternate-file if you want to understand it better). It’s what vim uses to switch between files when you use Ctrl-^, and you could do the same thing with :e Ctrl-r #. I rarely use this, but hopefully you are more creative than I am.

The expression and the search registers

The expression register ("=) is used to deal with results of expressions. This is easier to understand with an example. If, in insert mode, you type Ctrl-r =, you will see a “=” sign in the command line. Then if you type 2+2 <enter>, 4 will be printed. This can be used to execute all sort of expressions, even calling external commands. To give another example, if you type Ctrl-r = and then, in the command line, system('ls') <enter>, the output of the ls command will be pasted in your buffer.

The search register, as you may have imagined, is where the latest text that you searched with /, ?, * or # is. If, for example, you just searched for /Nietzsche, and now you want to replace it with something else, there is no way you are going to type “Nietzsche” again, just do :%s/<Ctrl-r />/mustache/g and you are good to go.

Macros

You may already be familiar with vim’s macros. It’s a way to record a set of actions that can be executed multiple times (:h recording if you need more information). What you probably didn’t know is that vim uses a register to store these actions, so if you use qw to record a macro, the register "w will have all the things that you did, it’s all just plain text.

The cool thing about this is that, as it is just a normal register, you can manipulate it as you want. How many times have you forgotten that step in the middle of a macro recording and had to do it all over again? Well, fixing that is as simple as editing a register.
For example, if you forgot to add a semicolon in the end of that w macro, just do something like :let @W='i;'. Noticed the upcased W? That’s just how we append a value to a register, using its upcased name, so here we are just appending the command i; to the register, to enter insert mode (i) and add a semicolon.
If you need to edit something in the middle of the register, just do :let @w='<Ctrl-r w>, change what you want, and close the quotes in the end. Done, no more recording a macro 10 times before you get it right.

Another cool thing about this is that, as it’s just plain text in a register, you can easily move macros around, applying it in other vim instance, or sharing it with someone else. Think about it, if you have that register in your clipboard, you can just execute it with @+ ("+ is the clipboard register). Try it, just write “ivim is awesome” anywhere, then copy it to your clipboard, and execute @+ in a vim buffer. How cool is that?

Wrapping up

Understanding how registers work is quite simple, and although you are not going to use them every 5 minutes, it certainly will avoid some annoyances, like losing a yanked text, of having to record a macro again. I covered the things that I use the most, but there is more. If you are curious about what a small delete or a black hole register is, you should definitely read the short and easy to follow documentation in :h registers.

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