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June 20, 2017

Infinite recursion in Rails associations

I’m working on a Rails 5.0 project that is using an existing database. This kind of project is more difficult than creating a database from scratch using Rails migrations. One problem is that the existing database doesn’t use Rails conventions for the names of its columns. That led me to a bone-headed mistake in my model associations that caused Rails to get into an infinite recursion.

May 30, 2017

Unblock sound on resume in Linux Mint 18

On the ThinkPad T60p and T61, using both Linux Mint 17 and 18, sound is not properly initialized after a suspend/resume cycle. The symptom is that after a resume, playing a video on YouTube produces no sound. The fix is to play a sound file using the /usr/bin/play utility, which apparently unblocks or reinitializes the audio device.

March 18, 2017

KVM on Linux Mint 18

I’ve been running Koha on Debian 8 in a VMware Workstation virtual machine, to test it prior to deployment on Linode for a real library. Yesterday I decided to investigate running this VM in KVM, the native Linux virtualization system that is used at Linode. The conversion went well on both Linux Mint 17 and 18. What follows are the steps I used on Mint 18 (Mate edition).

March 10, 2017

Pandoc on Linux Mint 18

As mentioned earlier, I use Pandoc instead of a word processor to prepare printed documents. Installing it on Linux Mint 18 reminded me that in order to create PDF files, you need to install more than Pandoc itself. Here is what I had to do to install Pandoc and the Latex files it requires:

sudo apt-get install pandoc lmodern texlive-latex-recommended \
                     texlive-latex-extra texlive-fonts-recommended

March 4, 2017

Emacs key bindings in Firefox on Linux Mint Mate or Cinnamon

Firefox can use Emacs key bindings in editable text fields, but the method for enabling this feature has changed in Mint over the years. In the Mate edition of Linux Mint, this command will do the trick:

gsettings set org.mate.interface gtk-key-theme 'Emacs'

In the Cinnamon edition of Linux Mint, use this:

gsettings set org.cinnamon.desktop.interface gtk-key-theme 'Emacs'

March 1, 2017

VMware Workstation 11 on Linux Mint 18

VMware Workstation 11 was released before Linux Mint 18 (and its parent, Ubuntu 16.04). Because the Linux kernel has changed, the Workstation installer fails to compile the vmmon and vmnet modules. Fixing this requires some minor patches. Once this is done, Workstation itself won’t start; fixing this requires a minor patch to a couple of shell scripts.

January 22, 2017

Bill and Me

I once spent a weekend with Bill Gates and some of his cronies, including Paul Allen, before either of them became rich and famous. It was just a matter of chance, and it didn’t seem all that big of a deal at the time.

January 18, 2017

Koha on Linode

Koha is an open source library system that is used widely throughout the world, and especially in Vermont. For various reasons (including financial) our library was not able to join either of the two consortia of Koha users in Vermont. So I installed Koha on Linode for the exclusive use of our library.

Linode is a hosting service that provides low-cost Linux virtual servers, called “Linodes”. Installing Koha in a Linode is a straightforward process, but it does require that you to be somewhat comfortable with typing commands at a command prompt.

January 17, 2017

Linux Mint on a 2008 Macbook

I have access to an old (2008) white Macbook that is not being used due to the age of its operating system. New versions of Firefox can’t be installed on this machine without an operating system upgrade, and the upgrade path for old MacBooks doesn’t appear to be free or easy. So I decided to see if I could install Linux Mint 17 (LTS) on the MacBook. Supposedly it was possible, but I wanted to see for myself.

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