chapters/01.markdown @ 0f37d5cc8d29

Echoing Messages
================

The first piece of Vimscript we'll look at is `echom`.

You can read the full documentation for the command by running `:help echom` in
Vim.  As you go through this book you should try to read the `:help` for every
new command you encounter to get a better understanding of how to use each one.

Run the following command:

    :::vim
    :echo "Hello, world!"

You should see `Hello, world!` appear at the bottom of the window.

Persistent Echoing
------------------

Now run the following command:

    :::vim
    :echom "Hello again, world!"

You should see `Hello again, world!` appear at the bottom of the window.

To see the difference between these two commands, run one more new command:

    :::vim
    :messages

You should see a list of messages.  `Hello, world!` will *not* be in this list,
but `Hello again, world!` *will* be in it.

When you're writing more complicated Vim scripts later in this book you may find
yourself wanting to "print some output" to help you debug problems.  Plain old
`:echo`will print output, but it will often disappear by the time your script is
done.  Using `:echom` will save the output and let you run `:messages` to view
it later.

Comments
--------

Before we move on we should mention comments.  When you write Vimscript code (in
your `~/.vimrc` file or another one) you can add comments with the `"`
character, like this:

    :::vim
    " Make space more useful
    nnoremap <space> za

This doesn't *always* work (that's one of those ugly corners of Vimscript), but
in most cases it does, and we'll talk about when it won't (and why that
happens).

Exercises
---------

Read `:help echo`.

Read `:help echom`.

Read `:help messages`.

Add a line to your vimrc file that displays a friendly ASCII-art cat (`>^.^<`)
whenever you open Vim.