Thursday, June 28, 2018

Errata for Articles on

DK Smith has offered me his time to point out some errors, spelling mistakes etc. This page will document his findings.

Saturday, June 23, 2018

Linode Box Images

git prompts for passphrase after mac os upgrade

  1. Create (or edit if it exists) the following ~/.ssh/config file:
    Host *
      UseKeychain yes
      AddKeysToAgent yes
      IdentityFile ~/.ssh/id_rsa
  2. eval "$(ssh-agent -s)" 
  3. ssh-add -K ~/.ssh/id_rsa

Installing Rugged on Mac OS

Check if Mac is 64 bit: 

getconf LONG_BIT

ERROR: CMake is required to build Rugged
cat /Users/bparanj/.rvm/gems/ruby-2.3.1@headache/extensions/x86_64-darwin-17/2.3.0/rugged-
ERROR: CMake is required to build Rugged.
brew install cmake

Must be superuser to create this extension.


createuser --superuser postgres2

gpg: keyserver receive failed: No route to host


gpg-connect-agent --dirmngr 'keyserver --hosttable'


gpg --keyserver hkp:// --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

Friday, June 22, 2018

When to Apply Memoization

Apply memoization, when two conditions are met:

1. Optimal sub structure
2. Overlapping sub problems

Tuesday, June 19, 2018

Make sure that `gem install libv8 -v '' --source ''` succeeds before bundling.

This happened on Mac OS 10.10.5. I needed a specific version of libv8, so I used the -v flag in gem install.


gem install libv8 -v -- --with-system-v8
bundle config build.libv8 --with-system-v8

Monday, June 18, 2018

SSL Notes

git clone
cd letsencrypt
./letsencrypt-auto --apache --rsa-key-size 4096

./letsencrypt-auto --apache -d -d -d -d -d

SSL with Let's Encrypt in Apache