DEMO.md

A Demo of demosh

This is the documentation - and executable code! - for demoing demosh itself. The easiest way to use this file is, unsurprisingly, to execute it with demosh.

Things in Markdown comments are safe to ignore when reading this later. When executing this with demosh, things after the horizontal rule below (which is just before a commented @SHOW directive) will get displayed.

The demo doesn't really have other external requirements, but it's intended to be a Real Demo (if such a thing really exists), so it uses hooks and all that jazz.

---

Introducing demosh

This is demosh, the Demo SHell. It can read Markdown files or shell scripts, displaying commentary, typing commands out and then running them. It lives at https://github.com/BuoyantIO/demosh.

When reading Markdown (like this file), demosh will display "normal text" and execute commands in bash blocks, like so:

echo 'Hello, world!'

Commands really don't have to be as simple as that, of course: demosh can manage fairly complex stuff:

now=$(date +"%Y-%m-%dT%H:%M:%S")

echo "The previous command ran at $now"

demosh also understands functions:

say_hello () {
    echo "Hello, world!"
}

say_hello

As you would expect, variables and functions persist across blocks:

echo "The previous command ran at $now."

If we use curly braces for the variable substitution, demosh will do the interpolation when typing the command.

echo "The previous command ran at ${now}."

Here's that function call again.

say_hello

Another helpful thing that demosh can do is to let you back up and run things again, by hitting -, or skip things by hitting +.

echo "DON'T RUN THIS COMMAND!!! back up and say hello again instead."

As you've seen, demosh pretends to type things out for you to make the demo a little more realistic. For long commands, though, you can always skip to the end with SPACE:

curl https://httpbin.org/ip \
    | grep origin \
    | cut -d: -f2 \
    | tr -d ' ' \
    | tr -d '"'

You can also skip to the end and immediately run it with RETURN:

curl https://httpbin.org/ip \
    | grep origin \
    | cut -d: -f2 \
    | tr -d ' ' \
    | tr -d '"'

demosh also has macros and hooks that you can use, for example, to control livecast setups. For example, let's flip over and look at the web browser displaying the demosh repo.

That was using a macro to:

• use a hook to show the browser
• wait for a RETURN back in the demosh window
• use another hook to flip back to demosh

If the hooks aren't set, the macro will just make you hit RETURN to proceed, rather than failing.

Put it all together and you can show the demo you're seeing now by running the Markdown file we're going to show you next (assuming the hooks are working, of course.)

#@wait
#@ifhook show_editor
  #@show_editor
  #@wait_clear
  #@show_terminal
#@endif

So that's the whirlwind tour of demosh -- hope you enjoyed it! We'll finish by using a hook to go back to the slides.