Toggle synchronize-panes(send command to all panes)
panes
// what it does
setw synchronize-panes toggles the window's synchronize-panes option, after which every keystroke you type is broadcast to all panes in that window at once. It's built for running the same commands across several servers or sessions side by side. Called with no value it simply flips the flag on or off each time.
// tmux command
: setw synchronize-panes// gotcha
It's easy to forget it's on — you'll type in one pane and unknowingly fire the command in every pane, which is dangerous with destructive commands. It's per-window and has no default keybinding, so bind it or run it from the prompt.