I have a prompt. I want to send a clear or ls to all my byobu windows (opened with F2), by typing it only once.
Is there a way to do that?
This was such a phenomenal question, and something that I've been wanting to do for so long, that I just put a couple of scripts together, added to Byobu-5.73, and released the new feature :-)
As of that version of Byobu, you can now use Shift-F9 to enter a command and send to all panes (splits), or Ctrl-F9 to enter a command and send to all windows.
You can watch a demo here: http://blog.dustinkirkland.com/2014/09/apply-updates-to-multiple-systems.html
This feature is available in Ubuntu 14.04 LTS (trusty), or you can always install the latest version from ppa:byobu/ppa or build/install from source.
Full disclosure: I am the author and maintainer of Byobu.