Don't display the MOTD when an explicit command is run. (possibly via authorized_keys(5) restrictions), even when a pseudo-terminal has been allocated for the session. In other words, only display the MOTD when the server starts the user's default shell.

#!/bin/sh
set -e

test "$1" = 'remove' || test "$1" = 'deconfigure' || exit 0
if test -x /etc/init.d/dropbear; then
  if test -x /usr/sbin/invoke-rc.d; then
    invoke-rc.d dropbear stop
  else
    /etc/init.d/dropbear stop
  fi
fi