Engineering & Code explores the full stack of modern tech—from bits and transistors to cloud fleets and formal proofs. Here you’ll find clear, rigorous walk-throughs of software design, embedded hardware, security architecture, and the physics that underpins them, always paired with code, schematics, and reasoning you can put to work.
First I had to backup my database from Heroku — so I created the database in PostGresSQL. heroku pgbackups:capture curl -o latest.dump `heroku pgbackups:url` pg_restore --verbose --clean --no-acl --no-owner -h localhost -d booher_blog latest.dump Armed with that and the handy Induction I then needed to get my data into a format easily imported by WordPress. […] read more
So I deleted all my pictures, and I restored them which resulted in a bunch of corrupted images; thousands of corrupted images. To fix this, I wrote the following script in MATLAB using the image processing toolbox: // insert blog here Using matlab I tried to determine what a corrupted image is. First when using […] read more
I had a lot of data in MySql in a rails application, but I moved to Mongo on a new application and wanted to give the client a nice archive of excel files for each client. It has been a long time since I’ve worked with visual basic, but it came back quickly. I was […] read more
[mathjax] Here we tackle what a Radar needs to accurately measure a target’s position, size and motion. (This is nothing new, just a placeholder for some of my notes.) First of all, everything depends on $SNR$, and the parameter estimation happens in the main computer of a Radar. The theoretical rms error of a measurement […] read more
This error was pretty hard to solve. I emailed heroku support and they recommended: “https://github.com/ddollar/heroku-accounts”:https://github.com/ddollar/heroku-accounts bq. For git commands to work git needs to use the ssh key associated with that account. It’s probably choosing a key associated with a different account which is causing these permissions errors. You can use a ~/.ssh/config file to […] read more
If I have two Mongoid models joined by a has_and_belongs_to_many relationship, Users and Groups. I need to quickly and efficiently sort by the most popular groups which really should be done with a counter_cache. However, counter_caches are implemented in rails by setting a callback to update the counter cache every time a child model is […] read more
In one of my applications, I have the following config files that are excluded from git: * config/mongoid.yml * config/application.yml * config/mailserver_setting.rb * config/omniauth_settings.rb For deploying to a regular server, I just add tasks to my capistrano deployment file to create sym-links to a shared directory. In this case I have to modify my application […] read more
My requirements: – All files on my laptop will be on my DNS-323 Network attached storage device – Any changes made to the shared drive on the DNS-323 will propagate to my Mac – This happens securely and safely The problem is that there are scant resources online to do this. (Isn’t this done frequently?) […] read more
Handbrake is amazing with active development and a great community. When I wanted to transfer a bunch of lectures to iphone/ipod touch format, I faced the time-consuming challenge of converting a hundred files using the Handbrake gui and figuring out the complicated set of options for HandbrakeCLI — their nightly build standalone. So, here is […] read more
So you didn’t set up automatic backups and need to recover your data? Don’t try digging it out of mysql, look no further than your rails production log. OK, try a bit with mysql, because the rails production log is a terrible way to recover your data. Only use as a last resort, but when […] read more