Create/Attach tmux session on ssh

ssh_tmux.config

# Place this at the end of the ssh config to launch a tmux session called 'ssh' when logging in via SSH or attach to it when it exists.
# * Don't launch tmux then ssh is called with a command (like 'ssh <remote> <command>')
# * If tmux is not installed, fall back to the login shell
# * Print the MOTD message in a temporary split-window on creating/attaching a session (will close on enter key)
Match exec "[[ $(ps h o args p $PPID | wc -w) -eq 2 ]]"
    RequestTTY yes
    RemoteCommand command -v tmux > /dev/null 2>&1 && tmux new-session -A -s ssh \; split-window 'motd=$(cat /run/motd.dynamic 2>/dev/null || cat /etc/motd 2>/dev/null); lines=$(echo "$motd" | wc -l); tmux resize-pane -y $((lines + 1)); echo "$motd"; read -r _' || exec $SHELL -l