Basic Mapping

If there's one feature of Vimscript that will let you bend Vim to your will more than any other, it's the ability to map keys. Mapping keys lets you tell Vim:

When I press this key, I want you to do this stuff instead of whatever you would normally do.

We're going to start off by mapping keys in normal mode. We'll talk about how to map keys in insert and other modes in the next chapter.

Type a few lines of text into a file, then run:

:map - x

Put your cursor somewhere in the text and press -. Notice how Vim deleted the character under the cursor, just like if you had pressed x.

We already have a key for "delete the character under the cursor", so let's change that mapping to something slightly more useful. Run this command:

:map - dd

Now put your cursor on a line somewhere and press - again. This time Vim deletes the entire line, because that's what dd does.

Special Characters

You can use <keyname> to tell Vim about special keys. Try running this command:

:map <space> viw

Put your cursor on a word in your text and press the space bar. Vim will visually select the word.

You can also map modifier keys like Ctrl and Alt. Run this:

:map <c-d> dd

Now pressing Ctrl+d on your keyboard will run dd.

Commenting

Remember in the first lesson where we talked about comments? Mapping keys is one of the places where Vim comments don't work. Try running this command:

:map <space> viw " Select word

If you try pressing space now, something horrible will almost certainly happen. Why?

When you press the space bar now, Vim thinks you want it to do what viw<space>"<space>Select<space>word would do. Obviously this isn't what we want.

If you look closely at the effect of this mapping you might notice something strange. Take a few minutes to try to figure out exactly what happens when you use it, and why that happens.

Don't worry if you don't get it right away -- we'll talk about it more soon.

Exercises

Map the - key to "delete the current line, then paste it below the one we're on now". This will let you move lines downward in your file with one keystroke.

Add that mapping command to your ~/.vimrc file so you can use it any time you start Vim.

Figure out how to map the _ key to move the line up instead of down.

Add that mapping to your ~/.vimrc file too.

Try to guess how you might remove a mapping and reset a key to its normal function.