tmux-cssh

#!/bin/sh

usage() {
  echo "Usage: $0 user1@host1 user2@host2 host3 host{4..6} host7 host8 [...]"
}
[ $# -lt 1 ] && usage && exit 1

create_ssh_pane() {
  local session=$1
  local host=$2

  tmux has-session -t $session 2>/dev/null \
    && tmux split-window -t $session "exec ssh $host" \
    || tmux new-session -d -s $session "exec ssh $host"

  tmux select-layout -t $session tiled >/dev/null
}

export session="cssh-$$"
for host in "$@"; do
  create_ssh_pane $session $host
done
#tmux set-window-option -t $session status off >/dev/null
tmux set-window-option -t $session synchronize-panes on >/dev/null
exec tmux attach -t $session