Focus on the window with ID of 12345

Command-line automation for X11.
More information: <https://manned.org/xdotool>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

xdotool windowfocus --sync {{12345}}

click the source code to copy install xdotool on any operating system with command-not-found.com