Rails 2.3.x upgrades fix security vulnerabilities and API changes across patch levels, with extra CSRF, XSS, and JSON gem updates needed on some releases.

Selecting specific columns limits loaded attributes and can make records read only, while SQL expressions can add computed fields for sorting and display.

Zombie processes appear when child processes exit but the parent never waits, leaving defunct entries in ps; fixing or restarting the parent removes them.

Backbone plugin for custom getter and setter logic on model attributes, enabling computed values and validation without changing core model code.

ActionMailer defaults to http in email links, which can expose session cookies to SSL-stripping. Set default_url_options or the link protocol to use https where needed.

Keeping git branches linear avoids cluttered merge commits when pulling updates. Setting pull.rebase=true makes git pull rebase by default.

Custom .irbrc files can make irb and the Rails console more useful with extra methods, nicer printing, editor integration, and app-specific prompts.

Virtus boolean attributes need Virtus::Attribute::Boolean rather than Boolean, because Ruby has no native Boolean class and Virtus will not coerce it correctly.

Capistrano API changes can break deployments with older deploy.rb files; bundling it and using bundle exec helps keep releases working.

Broken speaker output on Ubuntu can often be restored by restarting the audio stack with pulseaudio -k and reloading ALSA.

Backported Ruby 1.8.7–2.0.0 features for older Ruby versions improve compatibility and access to newer core APIs without upgrading the interpreter.

Subscribe to the Ruby on Rails security mailing list without a Google account by using a direct boxsubscribe URL instead of the web interface.

Frequent deployments fill application servers with old releases, tmp files, and stale compiled assets. Capistrano can automate release and asset cleanup to prevent disk-space exhaustion.

Keyboard remapping in Ubuntu lets you change key behavior when layouts or hardware keys are inconvenient. xmodmap can adjust mappings using keycodes from xev.

Lightweight WYSIWYG HTML editing for web apps, with a cleaner interface than TinyMCE or CKEditor and Rails integration.

Launch the GNOME disk utility from the terminal with sudo palimpsest.

Use rvm in a script shebang to run Ruby with a specific version instead of the system default.

Absolutely positioned boxes can use opposing offsets on both sides in modern browsers; only IE6 and older break this layout.

Need to remove cookie data during a Capybara scenario when browser state must reset before the test ends.

Periodic command output in an awesome panel can be turned into a widget with a timeout timer and escaped text.

Split panes in LibreOffice Calc can end up in awkward positions; moving the dividers off screen and toggling splitting restores the default layout.

ActiveRecord can inherit without STI when no type column exists or inheritance_column is overridden, making form models and presenters possible.