Mac tips and tricks

Empty trash from USB drive: rm -Rf /Volumes/NAME_OF_USB_DRIVE/.Trashes/*

Take screen shot:

1. Press Command-Shift-4.

2. Move the crosshair pointer to where you want to start the screenshot.

3. Drag to select an area.

4. When you've selected the area you want, release your mouse or trackpad button.

5. Find the screenshot as a .png file on your desktop.