I take no credit. SSH tmux multiplexer

mu.sh

#!/usr/bin/env bash

set -exo pipefail

decs_insts=$(aws --region us-east-1 ec2 describe-instances)

ssh_list=($(echo $decs_insts | jq -r --arg match "${1}" '.Reservations[]|select(.Instances[]|select((.Tags[]|select(.Key=="Name")|.Value)|match($match)))|select(.Instances[]|select(.State|select(.Name=="running")))|.Instances[].PrivateIpAddress' | tr '\r\n' ' '))

split_list=()
for ssh_entry in "${ssh_list[@]:1}"; do
    split_list+=( split-pane ssh "$ssh_entry" ';' )
done

tmux new-session ssh "${ssh_list[0]}" ';' \
    "${split_list[@]}" \
    select-layout tiled ';' \
    set-option -w synchronize-panes