xprop

A tool for displaying window and font properties in an X server. More information: https://manned.org/xprop.

• Display the name of the root window:

xprop -root WM_NAME

• Display the window manager hints for a window:

xprop -name "{{window_name}}" WM_HINTS

• Display the point size of a font:

xprop -font "{{font_name}}" POINT_SIZE

• Display all the properties of the window with the id 0x200007:

xprop -id {{0x200007}}