chapters/01.markdown @ 0baa9f045283

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

The first pieces of Vimscript we'll look at are the `echo` and `echom` commands.

You can read their full documentation by running `:help echo` and `:help echom`
in Vim.  As you go through this book you should try to read the `:help` for
every new command you encounter to learn more about them.

Try out `echo` by running the following command:

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

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

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

Now try out `echom` by running 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 the following:

    :::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 Vimscript 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 moving on, let's look at how to add comments.  When you write Vimscript
code (in your `~/.vimrc` file or any other 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.  Later 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.