/boot can fill up from old kernel images and initramfs files, blocking upgrades and updates. Removing unused kernels and shrinking initramfs frees space safely.

Gnome and MATE panels can steal focus in Awesome WM 3.5 when switching desktops. A window rule and an autofocus.lua replacement prevent the panel from taking focus.

External displays on a docking station may fail to activate or mirror the same layout; resetting them and reapplying xrandr settings can work around a kernel bug.

Dual-screen presentations on Linux can keep speaker notes or a projector preview visible without cloning displays. x11vnc and a VNC viewer provide a local preview of the second screen.

Upgrading to Bundler 1.13.x can break parallel_tests with a LoadError when loading Gherkin formatters. Setting bundle config --local disable_exec_load true restores the old behavior.

Command-line tests with Aruba can accidentally run real external executables; Aruba Doubles provides stubs for those binaries when PATH is adjusted with Aruba's official API.

Rake tasks appear in rake -T only when they have descriptions; removing comments or whitelisting tasks keeps internal tasks out of the task list.

Memoized ActiveRecord values can stay stale in specs even after reload; re-finding the record or clearing memoization avoids false failures.

Ruby module subclassing injects state and defines accessors when included, enabling trait-like macros and partial classes for cleaner model organization.

Haml mangles Angular 1 dynamic class attributes and can trigger [$parse:syntax] errors. Use ng-class or avoid Haml class interpolation.

Sidekiq monitoring needs a JSON status endpoint for queue sizes, worker activity, and recent failures. A cron-triggered heartbeat job and Redis timestamps let external checks detect stalled background processing.

AngularJS service kinds differ in configurability, injection style, and object shape; factories are usually the default choice, while providers support configuration and decorators extend existing services.

closure_tree adds hierarchical tree support to ActiveRecord models with efficient reads, pre-ordered trees, and safer concurrent updates than ancestry.

AngularJS -watch registrations can be removed after a condition is met, avoiding unnecessary change detection once a scoped value appears.

ls becomes slow in very large directories because it sorts names and formats columns before printing. Disabling both yields immediate streaming output.

Run a command at regular intervals and watch its output update, useful for monitoring changing files or other live system state with watch.

Use git difftool to open diffs in a graphical viewer like Meld when the terminal diff is not enough.

Browser-based OCR for scanned documents and images, with Web Worker processing and support for many input sources. Accuracy drops on distorted pages, mixed content, and layouts with tight borders.

VCR request replay depends on matching new HTTP requests to recorded ones; :match_requests_on lets you customize matching by URI, path, or a custom lambda.

git diff can show more surrounding lines for each change, making it easier to understand context in modified files.

VCR tests can flicker when recorded requests change because of randomness, timestamps, or generated sequences, making cassette mismatches hard to diagnose.

The MATE panel clock can use a custom strftime format instead of the default display, making compact date-and-time layouts possible.

SVGs can be styled with CSS only when embedded inline; using them as images or sprites blocks styling, and IE support is limited.