A portable fast MOTD similar to Ubuntu's.

Long story short:

1. Copy motd.sh to /etc.
2. Edit /etc/pam.d/system-login:

-session    optional   pam_motd.so          motd=/etc/motd
+session    optional   pam_exec.so          stdout /etc/motd.sh

1. Copy motd.sh to /etc.
2. Edit /etc/pam.d/login and /etc/pam.d/sshd:

-session    optional   pam_motd.so          motd=/run/motd.dynamic
+session    optional   pam_exec.so          stdout /etc/motd.sh

3. (Optional) Disable static motd message:

Edit /etc/pam.d/login and /etc/pam.d/sshd

-session    optional     pam_motd.so noupdate

1. Copy motd.sh to /etc.
2. Put this into your ~/.config/fish/config.fish:

if [ xterm != "dumb" ]
  bash /etc/motd.sh; or echo "Failed to show MOTD."
end

If you don't like scripts in /etc, feel free to choose any other location.