How to clear bell state from all tmux windows - terminal

Question

I help maintain a large number of Unix-like servers, and so keep a script called tmux-rebuild that I use to rebuild all the tmux sessions and windows with SSH links to each server.
I have tmux configured to show the window's name in red with an exclamation mark in its status bar when a terminal bell character is printed in that window. This is very handy for programs like irssi alerting me to when I have messages in another window.
I also have my $PS1 set up on every server to print a terminal bell at the end of every prompt. This is useful because if I run a long job in one window and switch to another, I can immediately see when it's finished because when my prompt is written to the screen after the job is done, tmux makes the window name come up in red with an exclamation mark. This is great for my workflow.
However it causes a slight problem with the rebuild script mentioned above, because when I start up tmux after running it, every window in every session is flagged in red, due to the first prompt being printed to the screen. This makes the feature useless until I visit every window, and there are something like 40-50 of them.
Is there something I can add to my script that will clear all alerts from sessions and windows after they are created? I don't mind using a kludge if necessary.

Answer 1

From the tmux man page, specifically the last sentence here:
kill-session [-aC] [-t target-session]
Destroy the given session, closing any windows linked to it
and no other sessions, and detaching all clients attached
to it. If -a is given, all sessions but the specified one is
killed. The -C flag clears alerts (bell, activity, or
silence) in all windows linked to the session.
So, simply:
tmux kill-session -C

Answer 2

Figured out an acceptable workaround; I redefined the next/previous bindings to allow repeats:
# Allow repeats for next/prev window
bind-key -r n next-window
bind-key -r p previous-window
This allows me to quickly sweep up the alerts for all windows in a session by pressing my prefix key and tapping "n" until they're all clear, and I'm back in my original window.

Answer 3

With tmux 1.6 (and later), list-windows can generate customizable output, so it is fairly simple to read the output lines and make a loop that runs select-window for each window.
Add list-session (to loop over all sessions, optionally), and display-message (to parse session specifiers, and to record the current/“last” windows so they can be properly restored), and you might end up with something like this:
#!/bin/sh
# usage: tmux-select-each [session [...]]
#
# Select every window in specified session(s). If no sessions are
# specified, process all windows in all sessions.
#
# This can be handy for clearing the activity flags of windows in
# freshly spawned sessions.
if test $# -gt 0; then
for session; do
tmux display-message -p -t "$session:" '#S'
done
else
tmux list-sessions -F '#{session_name}'
fi |
while read -r session; do
active_window=$(tmux display-message -p -t "$session:" '#S:#I')
last_window=$(tmux display-message -p -t "$session:"\! '#S:#I' 2>/dev/null)
tmux list-windows -t "$session" -F '#{session_name}:#{window_index}' |
while read -r window; do
if test "$window" = "$active_window" ||
test "$window" = "$last_window"; then
continue
fi
tmux select-window -t "$window"
done
if [ -n "$last_window" ]; then
tmux select-window -t "$last_window"
fi
tmux select-window -t "$active_window"
done