useful x utils

Post it to not forget them. Thx alex for sharing.

xrandr - primitive command line interface to RandR extension

use case :

1. query screen, device, and etc

> xrandr

2. change dpi. It is useful when debugging device scale factor on Blink.

> xrandr --dpi 150

xwininfo - window information utility for X

use case :

1. query XID of an application

> xwininfo

2. query XID tree

> xwininfo -tree

xdotool - command-line X11 automation tool

use case :

1. reparent a window. for example, you can see your application (e.g. content_shell) via another application.

> xdotool windowreparent [source_window] destination_window

refer to XReparentWindow(3)

xdpyinfo - display information utility for X

use case :

1. query DPI

> xdpyinfo | grep inch