Set OSX terminal window background color per SSH hosts.

vsh.sh

#!/bin/sh
# Set TMUX terminal pane background color per SSH hosts
# alias ssh='path/to/vsh.sh'

_ssh_tmux_background () {
    [ -z "$TMUX_PANE" ] && return 0
    if [ -n "$1" ]; then
        hostname=$(command ssh -G "$@" | awk '$1=="hostname" { print $2; }')
        case "$hostname" in
        *.example.com)
            # blue
            style='bg=colour52'
            ;;
        *.example.net)
            # red
            style='bg=colour17'
            ;;
        esac
    else
        style=default
    fi

    tmux set-option -p -t "$TMUX_PANE" window-style "$style"
    tmux set-option -p -t "$TMUX_PANE" window-active-style "$style"
}

_ssh_tmux_background "$@"  # Parse Host
trap '_ssh_tmux_background' 0 1 2 3 15
command ssh "$@"