Vagrant: “The following SSH command responded with a non-zero exit status. “

Vagrant up often returns the following error running Chef scripts: The following SSH command responded with a non-zero exit status. Vagrant assumes that this means the command failed! mount -t vboxsf -o uid=`id -u vagrant`,gid=`id -g vagrant` v-csc-1 /tmp/vagrant-chef-1/chef-solo-1/cookbooks You can troubleshoot this by logging into the running server, then running the command (the password […]

Fixing “The box ‘base’ could not be found.” (Vagrant)

This is an indication that the the base virtual image is not configured, usually from forgetting to finish the installation. This image is copied, and modified to produce the desired virtualized environment. It’s easy to fix, by running the following: vagrant box add base http://files.vagrantup.com/lucid32.box It is also possible that you installed the box under […]

First Philadelphia Node.JS Meetup

I went to the first Philadelphia Node.JS meetup last night hosted by Zivtech. It was a mix of local developers at various stages in their careers. There were several informative impromptu presentations, including a demonstration of file transfer using web sockets and Node.JS and sending Apple IOS push notifications from Node.JS. Useful libraries: Socket.io – […]

Scraping a List of Adsense Sites Within a Niche

One of the challenges in web crawling and scraping is determining which URLs to scrape. It’s easy for a site to have many urls that aren’t visited by humans, like a stock photo site that uses an API to supplement its data. Sites with sessionid parameters or dynamic content may make many duplicate or similar […]

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How to find Pitches in Music

Have you ever wanted to find what chords were in a song? A good first step is to read the notes played during a short time interval. If several notes are played simultaneously, in order to figure out the notes, we need to separate the waveform into the individual frequencies. Fortunately there is a well-established […]

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Using Prolog to Generate Test Data

I’ve built several reporting systems where work was divided evenly between a charting UI and database scripts – an ETL job, report sql, and database schema. It’s nice to divide work between UI and database developers to take advantage of specialization, but not having data is always an issue for the first week or two […]

How to Write a Wav File in Scala

The following code will play a chord to a Wav file using Scala. This is adapted from sample code and uses the library here to handle the file format. One of the nice things about Scala is the ease of using existing Java code, since it runs on the JVM. I started this project by […]

Finding Corporate Sponsors of Open Source

I copied about 19,000 git repositories into a full-text solr index. Because commits are tied to email addresses this provides interesting insight into corporate open source contributions. The search front-end I added lets you search for programmers or companies, grouped by the number of commits. For example, searching for Linux returns the following results: linux-foundation […]