A Duet in Rhapsody

Louie Mueller BBQ,
originally uploaded by ryan.d.phillips.

Fantastic BBQ!

A few weeks ago, I saw videos of developers at the Apple WWDC conference doing their presentations with a clipboard tool within OSX, which pastes snippets of code from a queue. Developers at the conference do not need to remember or refer to a document to provide an example. Their focus is only on the presentation.

Today, I gave a presentation to a group of developers showing off some capabilities of different tools from the command-line. I find it hard thinking about what I’m going to say in a public forum and thinking of command line arguments at the same time. My presenter hat comes off and I put on my engineering hat. One solution I came up with in Linux is to use the Screen command line tool to pass commands to a running Screen session (created with `screen -S demo`). This script runs in a different terminal on my laptop display, and all I have to do is press enter throughout the presentation.

The presentation today was a royal success. Partly due to this script.

Update: I was asked to explain the following code snippet. The code sends commands to a screen session called ‘demo’. Created with the command above. It then loops through the command list and if the window is 0 pauses after each command to allow for explanation. If the window number is not zero it will execute the command without interaction in the screen window specified.

#!/usr/bin/env python

from subprocess import Popen

# set with -S on the screen commandline
screen_name = 'demo'

# window specifies the screen window to direct the command
commands = [
    {
        'window':0,
        'command':'ls -l',
        'post-command':'\n',
    },
    {
        'window':0,
        'command':'echo Hello World',
        'post-command':'\n',
    },
    # direct this command to window 1
    {
        'window':1,
        'command':'echo Hello from window 1',
        'post-command':'\n',
    },
]

def run_screen(screen_name, window, cmd):
    Popen(['screen', '-S', screen_name, '-p', str(window), '-X', 'stuff',
            cmd]).communicate()

for cmd in commands:
    if cmd['window'] == 0:
        print("(%(window)i) %(command)s" % cmd)
        run_screen(screen_name, cmd['window'], cmd['command'])
        if cmd['post-command']:
            print("+ %s" % cmd['post-command'].replace('\n', '<cr>'))
            raw_input('...waiting for keypress')
            run_screen(screen_name, cmd['window'], cmd['post-command'])
        print(".... talk about whats happening ....")
        raw_input()
    else:
        run_screen(screen_name, cmd['window'], cmd['command'])
        run_screen(screen_name, cmd['window'], cmd['post-command'])

It’s been way too long since the last blog post. A couple months ago, Kristine and I went on a long overdue cruise vacation from Long Beach to Mexico. We had a blast!

I definitely need to come up with a better name. Event-JSON is a BSD licensed JSON-RPC 2.0 server written in C with libevent2. Please direct patches to the project page on github.

Source: http://github.com/rphillips/obelisk

[Updated: Link]