multiple linux terminals send commands to all windows at the same time

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http://stackoverflow.com – Experts, say for example that i have 3 terminals (gnome-terminals open for example or xterm) open and i would like to group them toghether to send commands to all of them at the same time while typing on 1 single terminal, and latter on, un-group those terminals if i need to issue 1 command in a particular terminal. Is there any terminal application that could provide this capability? I've tried keyboardcast and is not exactly what i am looking for, since you have to actually type your command in 1 popup window thank you (HowTos)