Screenshot

macOS

• Use screencapture (built-in): screencapture -x output.png for silent capture, -i for interactive selection
• Capture specific window by PID: screencapture -l$(osascript -e 'tell app "AppName" to id of window 1') out.png
• For retina displays, output is 2x resolution by default — add -R x,y,w,h to capture exact pixel region
• iOS Simulator: xcrun simctl io booted screenshot output.png — faster and more reliable than screencapture

Linux

• gnome-screenshot for GNOME, spectacle for KDE, scrot for minimal/headless
• Headless X11: xvfb-run scrot output.png — creates virtual display for CI environments
• Wayland sessions break X11 tools silently — use grim for Wayland, slurp for region selection

Windows

• PowerShell built-in: Add-Type -AssemblyName System.Windows.Forms; [System.Windows.Forms.Screen]::PrimaryScreen | ... is verbose — prefer nircmd savescreenshot
• nircmd savescreenshot output.png works from CLI without dependencies on most Windows versions
• For programmatic capture, python -m PIL.ImageGrab works cross-platform but requires Pillow installed

Web Pages

• Playwright: npx playwright screenshot URL output.png --full-page — handles JavaScript rendering and scrolling
• Always wait for network idle: --wait-for-timeout=5000 or page never finishes loading dynamic content
• Full-page screenshots of long pages pixelate when viewed — split into viewport-sized chunks instead
• Puppeteer equivalent: page.screenshot({fullPage: true}) after networkidle0

Format and Quality

• PNG for UI/text (lossless), JPEG for photos (smaller files)
• JPEG quality 85-92 is optimal — below 80 shows artifacts on text, above 95 gains little
• WebP offers 25-35% smaller files than JPEG at same quality — supported everywhere except older Safari

Automation Patterns

• Add timestamps to filenames: screenshot-$(date +%Y%m%d-%H%M%S).png — prevents overwrites in batch jobs
• For comparison testing, use identical viewport sizes — different resolutions create false diffs
• CI screenshot artifacts: compress with pngquant or jpegoptim before upload — saves storage and transfer time