Cutting down the Ubuntu MOTD down to size

The Ubuntu message of the day (MOTD) is a chatty affair. A MOTD sends information to all users on login—A recent login message greeted me with 42 lines of questionable value.

Welcome to Ubuntu 18.04.2 LTS (GNU/Linux 4.15.0-1021-aws x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Mon Apr 20 01:01:24 UTC 2020

  System load:  28.97              Processes:             10
  Usage of /:   28.9% of 48.41GB   Users logged in:       0
  Memory usage: 61%                IP address for enp4s0: 10.0.101.001
  Swap usage:   0%

 * Kubernetes 1.18 GA is now available! See https://microk8s.io
   for docs or install it with:

     sudo snap install microk8s --channel=1.18 --classic

 * Multipass 1.1 adds proxy support for developers behind enterprise
   firewalls. Rapid prototyping for cloud operations just got easier.

     https://multipass.run/

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

 * Canonical Livepatch is available for installation.
   - Reduce system reboots and improve kernel security. Activate at:
     https://ubuntu.com/livepatch

99 packages can be updated.
1 update is a security update.

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

*** System restart required ***
Last login: Sun Apr 19 03:41:04 2020 from 192.168.0.1

Disable the verbose parts of the message

The commands listed below reduce the verbosity of the MOTD from 42 lines to 11 lines.

# Disable cron job that updates the Ubuntu news.
systemctl disable motd-news.timer

# Disable Ubuntu news.
sed -i -e 's/ENABLED=1/ENABLED=0/' /etc/default/motd-news

# Disable MOTD scripts by removing the executable bit so run-parts won't run
# them.
chmod -x \
    /etc/update-motd.d/10-help-text \
    /etc/update-motd.d/50-motd-news \
    /etc/update-motd.d/51-cloudguest \
    /etc/update-motd.d/80-livepatch \
    /etc/update-motd.d/91-release-upgrade \
    /etc/update-motd.d/95-hwe-eol \
    /etc/update-motd.d/98-reboot-required

# The legal notice gets appended to the MOTD by PAM. The simplest way
# to drop it from the MOTD is to delete the file.
rm -f /etc/legal

The trimmed message looks like:

Welcome to Ubuntu 18.04.2 LTS (GNU/Linux 4.15.0-1021-aws x86_64)

  System information as of Mon Apr 20 01:40:59 UTC 2020

  System load:  19.49              Processes:             10
  Usage of /:   28.9% of 48.41GB   Users logged in:       1
  Memory usage: 50%                IP address for enp4s0: 10.0.101.001
  Swap usage:   0%

152 packages can be updated.
1 update is a security update.

History of the Ubuntu MOTD

I'm not the first to discover the chatty MOTD. The inclusion of ads in the MOTD briefly outraged Hacker News and caused several bloggers to blog.

The best overview of the mechanics behind the Ubuntu MOTD is by David Kuhl in the AskUbuntu question: How is /etc/motd updated? To summarize, Ubuntu generates the MOTD by combining data from four sources.

  1. Scripts run by run-parts in /etc/update.motd/ like 00-header or 10-help-text.
  2. Binaries invoked by /etc/pam.d/login.
  3. SSH options from /etc/ssh/sshd_config, namely PrintLastLog.
  4. The /etc/legal file.

Script contents from /etc/update.motd/

For reference, here's the output of the stock scripts in /etc/update.motd/.

  • /etc/update.motd/00-header

    Welcome to Ubuntu 18.04.2 LTS (GNU/Linux 4.15.0-1021-aws x86_64)

  • /etc/update.motd/10-help-text

    * Documentation:  https://help.ubuntu.com
* Management:     https://landscape.canonical.com
* Support:        https://ubuntu.com/advantage

  • /etc/update.motd/50-landscape-sysinfo

    System information as of Mon Apr 20 01:15:45 UTC 2020

System load:  20.6               Processes:             1031
Usage of /:   28.9% of 48.41GB   Users logged in:       1
Memory usage: 43%                IP address for enp4s0: 10.0.0.1
Swap usage:   0%

  • /etc/update.motd/50-motd-news

    * Kubernetes 1.18 GA is now available! See https://microk8s.io
  for docs or install it with:

    sudo snap install microk8s --channel=1.18 --classic

* Multipass 1.1 adds proxy support for developers
  behind enterprise firewalls. Rapid prototyping for
  cloud operations just got easier.

    https://multipass.run/

  • /etc/update.motd/51-cloudguest

    Get cloud support with Ubuntu Advantage Cloud Guest:
  http://www.ubuntu.com/business/services/cloud

  • /etc/update.motd/80-livepatch

    Get cloud support with Ubuntu Advantage Cloud Guest:
  http://www.ubuntu.com/business/services/cloud

  • /etc/update.motd/90-updates-available

    152 packages can be updated.
1 update is a security update.

Legal text in the MOTD

The MOTD includes legal text in the login message. The simplest way to prevent it from appearing in the MOTD is to delete the file: rm /etc/legal. The file contains the following text:

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.