====== Dynamic Message of the Day (motd) ======
===== Quellen =====
  - https://wiki.debian.org/motd
  - https://oitibs.com/debian-jessie-dynamic-motd/
  - https://unix.stackexchange.com/questions/246436/how-to-set-a-dynamic-message-of-the-day-motd-in-debian-jessie-8-2-for-ssh
  - https://elhombrequereventodeinformacion.wordpress.com/2015/04/30/motd-handling-in-debian-jessie-fixed/

===== Setup =====
<code bash>
# install lsb-release 
apt install lsb-release
# install figlet to enable ASCII art
apt install figlet
# install lolcat to enable rainbow art
apt install lolcat
# install neofetch to display Linux Distribution art
apt install neofetch
# create directory
mkdir /etc/update-motd.d/
# change to new directory
cd /etc/update-motd.d/
# create dynamic files
touch 00-header && touch 10-sysinfo && touch 90-footer
# make files executable
chmod +x /etc/update-motd.d/*
# remove MOTD file
mv /etc/motd /etc/motd.BAK
# symlink dynamic MOTD file
ln -s /var/run/motd.new /etc/motd
# Optional: Fix bug in /etc/pam.d/sshd. See Source Link 3 and 4
nano /etc/pam.d/sshd
session    optional     pam_motd.so  motd=/run/motd.dynamic.new
session    optional     pam_motd.so noupdate
</code>

===== Config Files =====
<hidden 00-header -edit>
<code bash 00-header>
#!/bin/sh
#
#    00-header - create the header of the MOTD
#    Copyright (c) 2013 Nick Charlton
#    Copyright (c) 2009-2010 Canonical Ltd.
#
#    Authors: Nick Charlton <hello@nickcharlton.net>
#             Dustin Kirkland <kirkland@canonical.com>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

[ -r /etc/lsb-release ] && . /etc/lsb-release

if [ -z "$DISTRIB_DESCRIPTION" ] && [ -x /usr/bin/lsb_release ]; then
        # Fall back to using the very slow lsb_release utility
        DISTRIB_DESCRIPTION=$(lsb_release -s -d)
fi

figlet $(hostname)
printf "\n"

printf "Welcome to %s (%s).\n" "$DISTRIB_DESCRIPTION" "$(uname -r)"
printf "\n"
</code>
</hidden>

<hidden 10-sysinfo -edit>
<code bash 10-sysinfo>
#!/bin/bash
#
#    10-sysinfo - generate the system information
#    Copyright (c) 2013 Nick Charlton
#
#    Authors: Nick Charlton <hello@nickcharlton.net>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

date=`date`
load=`cat /proc/loadavg | awk '{print $1}'`
root_usage=`df -h / | awk '/\// {print $(NF-1)}'`
memory_usage=`free -m | awk '/Mem:/ { total=$2 } /buffers\/cache/ { used=$3 } END { printf("%3.1f%%", used/total*100)}'`
swap_usage=`free -m | awk '/Swap/ { printf("%3.1f%%", "exit !$2;$3/$2*100") }'`
users=`users | wc -w`
time=`uptime | grep -ohe 'up .*' | sed 's/,/\ hours/g' | awk '{ printf $2" "$3 }'`
processes=`ps aux | wc -l`
ip=`ifconfig $(route | grep default | awk '{ print $8 }') | grep "inet addr" | awk -F: '{print $2}' | awk '{print $1}'`

echo "System information as of: $date"
echo
printf "System load:\t%s\tIP Address:\t%s\n" $load $ip
printf "Memory usage:\t%s\tSystem uptime:\t%s\n" $memory_usage "$time"
printf "Usage on /:\t%s\tSwap usage:\t%s\n" $root_usage $swap_usage
printf "Local Users:\t%s\tProcesses:\t%s\n" $users $processes
echo
</code>
</hidden>

<hidden 90-footer -edit>
<code bash 90-footer>
#!/bin/sh
#
#    90-footer - write the admin's footer to the MOTD
#    Copyright (c) 2013 Nick Charlton
#    Copyright (c) 2009-2010 Canonical Ltd.
#
#    Authors: Nick Charlton <hello@nickcharlton.net>
#             Dustin Kirkland <kirkland@canonical.com>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

[ -f /etc/motd.tail ] && cat /etc/motd.tail || true
</code>
</hidden>