dynmotd

Dynamic Message of the Day — a single Bash script that displays system information on login.

Features

• Color schemes (switchable via config block at top of script)
• Enable/disable individual information sections
• Per-host description, environment label and SLA tag
• Maintenance log with add/delete/list support
• Automatic dependency installation on --install
• --update for non-interactive binary updates (Ansible / Puppet / cron)
• Multi-distribution support (Debian, RHEL, SUSE, Arch, Alpine families)
• All IPv4 addresses + optional IPv6 from all active interfaces
• Load average (1m / 5m / 15m) and realistic available memory (MemAvailable)
• Graphical utilization bars for memory, swap and disk
• Network interface state and link speed
• Optional Fail2Ban section — summary, per-jail IP list, parallel reverse DNS
• Optional Failed Systemd Services section (auto-hidden when all services are healthy)
• Parallel section rendering for fast output
• Update count cache to avoid slow package manager queries on every login
• LDAP / AD / NIS user support via getent
• Single self-contained shell script, no external dependencies beyond coreutils

Supported Linux Distributions

Distributions actively supported (last ~10 years, 2015 – 2026):

Debian family

Distribution	Versions / Releases	Status
Debian	8 (Jessie) – 12 (Bookworm)	Tested
Ubuntu	16.04 LTS – 24.04 LTS	Tested
Linux Mint	18 – 22	Tested
Raspberry Pi OS	Bullseye, Bookworm	Tested
Kali Linux	Rolling (2020+)	Tested
Pop!_OS	20.04 – 22.04	Compatible
Elementary OS	6 – 7	Compatible
MX Linux	19 – 23	Compatible
Devuan	3 – 5	Compatible
Zorin OS	16 – 17	Compatible

RHEL family

Distribution	Versions	Status
CentOS	7, 8, Stream 8/9	Tested
RHEL	7, 8, 9	Tested
Rocky Linux	8, 9	Tested
AlmaLinux	8, 9	Tested
Fedora	35 – 41	Tested
Oracle Linux	7, 8, 9	Compatible
CloudLinux	7, 8	Compatible

SUSE family

Distribution	Versions	Status
openSUSE Leap	15.x	Tested
openSUSE Tumbleweed	Rolling	Tested
SLES	12, 15	Compatible

Arch family

Distribution	Versions	Status
Arch Linux	Rolling	Compatible
Manjaro	Rolling	Compatible
EndeavourOS	Rolling	Compatible

Other

Distribution	Versions	Status
Alpine Linux	3.x	Compatible

"Tested" = verified by the author. "Compatible" = dependency auto-install supported, not explicitly tested. Tell me if you have verified it on a distribution not listed here.

Installation

The script must run as root.

sudo -i
git clone https://github.com/rtulke/dynmotd.git
cd dynmotd
./dynmotd.sh --install

--install automatically:

1. Detects your Linux distribution
2. Installs any missing dependencies via your native package manager
3. Copies the script to /usr/local/bin/dynmotd
4. Creates /etc/profile.d/motd.sh so dynmotd runs on every login
5. Runs first-time environment setup (function, environment label, SLA)

To verify the installation, log out and back in:

exit
sudo -i

Manual dependency installation

If you prefer to install packages yourself before running --install:

Debian / Ubuntu / Raspberry Pi OS / Mint

apt update && apt install -y coreutils procps hostname sed gawk grep dnsutils lsb-release

CentOS 7 / RHEL 7

yum install -y hostname procps-ng gawk bind-utils

CentOS Stream 8-9 / Rocky / AlmaLinux / RHEL 8-9

dnf install -y hostname procps-ng gawk bind-utils

Fedora

dnf install -y hostname procps-ng gawk bind-utils

openSUSE / SLES

zypper install -y hostname procps gawk bind-utils lsb-release

Arch / Manjaro

pacman -Sy inetutils procps-ng gawk bind

Alpine Linux

apk add bind-tools busybox-extras procps gawk

Usage

Usage: dynmotd [OPTION] [value]

  e.g.  dynmotd -a "deployed new SSL certificate"

Options:

  -a | --addlog "..."           Add a maintenance log entry
  -d | --rmlog  [line-number]   Delete a log entry by line number
  -l | --log                    List all log entries
  -c | --config                 Reconfigure environment settings
  -i | --install                Install dynmotd and its dependencies
  -U | --update                 Update binary only (no setup, safe for Ansible/cron)
  -u | --uninstall              Uninstall dynmotd (log deletion is optional)
  -v | --version                Show version and exit
  -h | --help                   Show this help

Uninstall

dynmotd --uninstall

The uninstaller asks two separate questions:

1. Whether to delete the log and configuration data in /root/.dynmotd/
2. Final confirmation before removing the binary and profile hook

System packages that were installed as dependencies are never removed automatically. Remove them with your package manager if desired.

Update

To update an already-installed dynmotd to a newer version without running the full setup again:

cd dynmotd
git pull
sudo bash dynmotd.sh --update

--update only replaces the binary at /usr/local/bin/dynmotd. It does not ask setup questions, does not touch logs or configuration, and does not reinstall packages — safe to run from Ansible, Puppet, or a cron job.

Configuration

Edit the config block at the top of the installed script:

vim /usr/local/bin/dynmotd

Enable / disable sections

Each section has an _INFO toggle and an optional _ALWAYS override:

Variable	Default	Description
SYSTEM_INFO	1	System info (hostname, IP, kernel, CPU, memory, load)
STORAGE_INFO	1	Storage / disk usage with utilization bars
NETWORK_INFO	1	Network interfaces — state and link speed
USER_INFO	1	User sessions and SSH keys
UPDATE_INFO	1	Available package updates
UPDATE_ALWAYS	0	Show Update section even when UPDATE_INFO="0"
ENVIRONMENT_INFO	1	Environment label (function, env, SLA)
FAILED_SERVICES_INFO	1	Failed systemd services (auto-hidden when none failed)
FAILED_SERVICES_ALWAYS	0	Always show Failed Services, even when all healthy (= none)
FAIL2BAN_INFO	1	Fail2Ban summary — total banned + jail overview
FAIL2BAN_ALWAYS	0	Always show Fail2Ban, even if not installed
SHOWFAIL2BAN_IPS	1	List banned IPs per jail (no DNS, no delay)
RESOLVEFAIL2BAN_IPS	1	Resolve banned IPs via reverse DNS (parallel, requires SHOWFAIL2BAN_IPS="1")
MAINTENANCE_INFO	1	Maintenance log entries
MAINTENANCE_ALWAYS	0	Show Maintenance section even when MAINTENANCE_INFO="0"
WEATHER_INFO	1	Weather via wttr.in (auto-hidden if curl unavailable or fetch fails)
WEATHER_ALWAYS	0	Always show Weather section, even if fetch fails (= unavailable)
WEATHER_CITY	(empty)	City for weather lookup — empty = auto-detect from server IP
WEATHER_CACHE_HOURS	1	Hours before weather data is re-fetched (0 = always live)
WEATHER_UNITS	(empty)	Unit system: m = metric, u = USCS, M = wind in m/s (empty = wttr.in default)
VERSION_INFO	1	Version banner

1 = enabled, 0 = disabled.

Section display order

Sections are rendered in this fixed order:

1. System Info
2. Weather
3. Storage Info
4. Network Interfaces
5. User Data
6. Update Info
7. Environment Data
8. Failed Services
9. Fail2Ban
10. Maintenance Information
11. Version banner

Maintenance log display

LIST_LOG_ENTRY="2"      # number of log lines shown in the MOTD

Update cache

UPDATE_CACHE_HOURS="6"  # hours before the update count is refreshed (0 = always live)

The update cache avoids running a full package manager check on every login. The cached count is stored in /root/.dynmotd/update_cache and refreshed automatically when it expires.

Color schemes

Seven schemes are pre-defined. Uncomment exactly one block to activate it (F1 = labels, F2 = borders, F3 = values, F4 = warnings):

#	Name	Character
1	DOT (default)	grey labels · pink borders · green values
2	Retro Hacker	all green, Matrix style
3	Retro Alert	all red, maximum urgency
4	Ocean	cyan/blue, cool and professional
5	Solarized Dark	grey with warm yellow accent
6	Nord	ice blue, clean and modern
7	Amber	brown/yellow, classic CRT terminal

Example — switching to Nord:

vim /usr/local/bin/dynmotd

Comment out the active scheme and uncomment Nord:

## 1. DOT - day of the tentacle (default)
#F1=${C_GREY}
#F2=${C_PINK}
#F3=${C_LGREEN}
#F4=${C_RED}

## 6. nord — ice blue, clean and modern
F1=${C_LBLUE}
F2=${C_LCYAN}
F3=${C_WHITE}
F4=${C_YELLOW}

Known Issues

Hostname not displayed correctly

The Hostname field uses hostname --fqdn. If /etc/hostname contains only the short name, only the short name is shown. Fix:

hostname mail.example.com
hostname > /etc/hostname

Also check /etc/hosts:

127.0.1.1  mail.example.com

Note: The Address v4 / Address v6 fields are read directly from network interfaces via ip -brief addr show and are not affected by hostname resolution.

SSH key shows "- Unknown -"

This happens when the key has no comment field. Either add a comment to the end of the key line in ~/.ssh/authorized_keys, or generate keys with:

ssh-keygen -C "your.name@example.com"