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linux-scripts/motd-generator.sh
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#!/usr/bin/env bash
#########################################################################################
#### motd-generator.sh — Generate a dynamic MOTD with system stats and health info ####
#### Shows hostname, IP, uptime, disk, load, memory, updates, and service status ####
#### Dry-run by default for --install — use --force to write to update-motd.d ####
#### ####
#### Author: Phil Connor ####
#### Contact: contact@mylinux.work ####
#### License: MIT ####
#### Version 1.02 ####
#### ####
#### Usage: ####
#### ./motd-generator.sh ####
#### ./motd-generator.sh --plain ####
#### ./motd-generator.sh --install --force ####
#### ####
#### See --help for all options. ####
#########################################################################################
set -euo pipefail
# ── Defaults ──────────────────────────────────────────────────────────
VERBOSE="${VERBOSE:-false}"
COLOR="${COLOR:-auto}"
DRY_RUN="${DRY_RUN:-true}"
MODE="${MODE:-display}"
PLAIN="${PLAIN:-false}"
MOTD_TARGET="${MOTD_TARGET:-/etc/update-motd.d/99-custom}"
# ── State ─────────────────────────────────────────────────────────────
SCRIPT_NAME="$(basename "$0")"
readonly SCRIPT_NAME
# ── Colors ────────────────────────────────────────────────────────────
setup_colors() {
if [[ "$COLOR" == "never" ]]; then
RED="" GREEN="" YELLOW="" CYAN="" BOLD="" DIM="" RESET=""
return
fi
if [[ "$COLOR" == "always" ]] || [[ -t 1 ]]; then
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[0;33m'
CYAN='\033[0;36m'
BOLD='\033[1m'
DIM='\033[2m'
RESET='\033[0m'
else
RED="" GREEN="" YELLOW="" CYAN="" BOLD="" DIM="" RESET=""
fi
}
# ── Logging ───────────────────────────────────────────────────────────
log() { echo -e "${CYAN}[INFO]${RESET} $*"; }
warn() { echo -e "${YELLOW}[WARN]${RESET} $*" >&2; }
err() { echo -e "${RED}[ERROR]${RESET} $*" >&2; }
verbose() { if [[ "$VERBOSE" == "true" ]]; then echo -e "${DIM}[DEBUG]${RESET} $*"; fi; }
# ── Data Gathering ───────────────────────────────────────────────────
get_hostname() {
hostname -f 2>/dev/null || hostname
}
get_primary_ip() {
local ip=""
if command -v ip &>/dev/null; then
ip=$(ip route get 1.1.1.1 2>/dev/null | grep -oP 'src \K[\d.]+' | head -1)
fi
if [[ -z "$ip" ]] && command -v hostname &>/dev/null; then
ip=$(hostname -I 2>/dev/null | awk '{print $1}')
fi
echo "${ip:-N/A}"
}
get_uptime() {
uptime -p 2>/dev/null || uptime | sed 's/.*up //' | sed 's/, [0-9]* user.*//'
}
get_disk_usage() {
df / 2>/dev/null | tail -1 | awk '{print $5}' | tr -d '%'
}
get_load_average() {
cut -d' ' -f1-3 /proc/loadavg 2>/dev/null || echo "N/A"
}
get_memory_usage() {
if [[ -f /proc/meminfo ]]; then
local total_kb avail_kb
total_kb=$(awk '/^MemTotal:/ {print $2}' /proc/meminfo)
avail_kb=$(awk '/^MemAvailable:/ {print $2}' /proc/meminfo)
if [[ "$total_kb" -gt 0 ]]; then
local pct
pct=$(awk "BEGIN { printf \"%.0f\", ($total_kb - $avail_kb) * 100 / $total_kb }")
local total_mb=$(( total_kb / 1024 ))
local used_mb=$(( (total_kb - avail_kb) / 1024 ))
echo "${pct}|${used_mb}|${total_mb}"
return
fi
fi
echo "0|0|0"
}
get_pending_updates() {
if command -v apt-get &>/dev/null; then
apt list --upgradable 2>/dev/null | grep -c "upgradable" || true
elif command -v dnf &>/dev/null; then
dnf check-update --quiet 2>/dev/null | grep -cE "^\S" || true
elif command -v yum &>/dev/null; then
yum check-update --quiet 2>/dev/null | grep -cE "^\S" || true
else
echo "N/A"
fi
}
get_logged_in_users() {
who 2>/dev/null | wc -l
}
get_failed_services() {
if command -v systemctl &>/dev/null; then
systemctl --no-legend --state=failed 2>/dev/null | wc -l
else
echo "N/A"
fi
}
# ── Color Thresholds ─────────────────────────────────────────────────
threshold_color() {
local value="$1"
local warn_at="${2:-75}"
local crit_at="${3:-90}"
if [[ "$value" -ge "$crit_at" ]]; then
echo "$RED"
elif [[ "$value" -ge "$warn_at" ]]; then
echo "$YELLOW"
else
echo "$GREEN"
fi
}
load_color() {
local load_1m="$1"
local cpus
cpus=$(nproc 2>/dev/null || echo 1)
local pct
pct=$(awk "BEGIN { printf \"%.0f\", ($load_1m / $cpus) * 100 }")
threshold_color "$pct" 75 90
}
# ── MOTD Output ──────────────────────────────────────────────────────
generate_motd_plain() {
local host ip up disk_pct load mem_info mem_pct mem_used mem_total
local updates users_count failed_count
host=$(get_hostname)
ip=$(get_primary_ip)
up=$(get_uptime)
disk_pct=$(get_disk_usage)
load=$(get_load_average)
mem_info=$(get_memory_usage)
mem_pct=$(echo "$mem_info" | cut -d'|' -f1)
mem_used=$(echo "$mem_info" | cut -d'|' -f2)
mem_total=$(echo "$mem_info" | cut -d'|' -f3)
updates=$(get_pending_updates)
users_count=$(get_logged_in_users)
failed_count=$(get_failed_services)
local dc mc lc
dc=$(threshold_color "$disk_pct" 75 90)
mc=$(threshold_color "$mem_pct" 75 90)
local load_1m
load_1m=$(echo "$load" | awk '{print $1}')
lc=$(load_color "$load_1m")
echo -e " ${BOLD}Hostname:${RESET} $host"
echo -e " ${BOLD}IP Address:${RESET} $ip"
echo -e " ${BOLD}Uptime:${RESET} $up"
echo -e " ${BOLD}Disk (root):${RESET} ${dc}${disk_pct}%${RESET}"
echo -e " ${BOLD}Load Average:${RESET} ${lc}${load}${RESET}"
echo -e " ${BOLD}Memory:${RESET} ${mc}${mem_used}M / ${mem_total}M (${mem_pct}%)${RESET}"
echo -e " ${BOLD}Pending Updates:${RESET} $updates"
echo -e " ${BOLD}Logged-in Users:${RESET} $users_count"
echo -e " ${BOLD}Failed Services:${RESET} $failed_count"
}
generate_motd_box() {
local host ip up disk_pct load mem_info mem_pct mem_used mem_total
local updates users_count failed_count
host=$(get_hostname)
ip=$(get_primary_ip)
up=$(get_uptime)
disk_pct=$(get_disk_usage)
load=$(get_load_average)
mem_info=$(get_memory_usage)
mem_pct=$(echo "$mem_info" | cut -d'|' -f1)
mem_used=$(echo "$mem_info" | cut -d'|' -f2)
mem_total=$(echo "$mem_info" | cut -d'|' -f3)
updates=$(get_pending_updates)
users_count=$(get_logged_in_users)
failed_count=$(get_failed_services)
local dc mc lc
dc=$(threshold_color "$disk_pct" 75 90)
mc=$(threshold_color "$mem_pct" 75 90)
local load_1m
load_1m=$(echo "$load" | awk '{print $1}')
lc=$(load_color "$load_1m")
local fc_color="$GREEN"
if [[ "$failed_count" != "N/A" && "$failed_count" -gt 0 ]]; then
fc_color="$RED"
fi
# Build rows as "label|value" pairs to measure widest content
local label_w=18
local rows=(
"Hostname:|$host"
"IP Address:|$ip"
"Uptime:|$up"
"Disk (root):|${disk_pct}%"
"Load Average:|$load"
"Memory:|${mem_used}M / ${mem_total}M (${mem_pct}%)"
"Pending Updates:|$updates"
"Logged-in Users:|$users_count"
"Failed Services:|$failed_count"
)
# Calculate box width from widest content
local header="System Status: ${host}"
local dateline
dateline=$(date '+%Y-%m-%d %H:%M:%S %Z')
local w=${#header}
[[ ${#dateline} -gt $w ]] && w=${#dateline}
local row label value row_len
for row in "${rows[@]}"; do
label="${row%%|*}"
value="${row#*|}"
row_len=$(( label_w + 1 + ${#value} ))
[[ $row_len -gt $w ]] && w=$row_len
done
# Add 2 for inner padding (space on each side)
w=$(( w + 2 ))
# Minimum width
[[ $w -lt 56 ]] && w=56
# Build box-drawing borders at calculated width
local bar
bar=$(printf '═%.0s' $(seq 1 $((w + 2))))
local border="╔${bar}╗"
local bottom="╚${bar}╝"
local sep="╠${bar}╣"
BOX_W=$w # export to _box_row
echo ""
echo -e " ${CYAN}${border}${RESET}"
printf " ${CYAN}║${RESET} ${BOLD}%-${w}s${RESET} ${CYAN}║${RESET}\n" "$header"
printf " ${CYAN}║${RESET} ${DIM}%-${w}s${RESET} ${CYAN}║${RESET}\n" "$dateline"
echo -e " ${CYAN}${sep}${RESET}"
_box_row "Hostname: " "$host"
_box_row "IP Address: " "$ip"
_box_row "Uptime: " "$up"
_box_row "Disk (root): " "${disk_pct}%" "$dc"
_box_row "Load Average: " "$load" "$lc"
_box_row "Memory: " "${mem_used}M / ${mem_total}M (${mem_pct}%)" "$mc"
_box_row "Pending Updates: " "$updates"
_box_row "Logged-in Users: " "$users_count"
_box_row "Failed Services: " "$failed_count" "$fc_color"
echo -e " ${CYAN}${bottom}${RESET}"
echo ""
}
_box_row() {
# Print a row inside the box with correct padding regardless of content length
# Usage: _box_row "Label:" "value" [color_prefix]
local label="$1"
local value="$2"
local color="${3:-}"
local inner_w="${BOX_W:-56}"
# Build the visible text (no ANSI)
local vis_text=" ${label} ${value}"
local vis_len=${#vis_text}
# Pad to fill the box
local pad_len=$(( inner_w - vis_len ))
[[ $pad_len -lt 0 ]] && pad_len=0
local padding
padding=$(printf '%*s' "$pad_len" '')
# Build output with optional color on value
if [[ -n "$color" ]]; then
printf " ${CYAN}║${RESET} %s %b%s${RESET}%s ${CYAN}║${RESET}\n" "$label" "$color" "$value" "$padding"
else
printf " ${CYAN}║${RESET} %s %s%s ${CYAN}║${RESET}\n" "$label" "$value" "$padding"
fi
}
# ── Install ──────────────────────────────────────────────────────────
install_motd() {
if [[ "$DRY_RUN" == "true" ]]; then
log "[DRY-RUN] Would install MOTD script to ${MOTD_TARGET}"
log "[DRY-RUN] Run with --force to actually install"
echo ""
log "Generated script preview:"
echo " #!/bin/bash"
echo " # Generated by ${SCRIPT_NAME} on $(date '+%Y-%m-%d %H:%M:%S')"
echo " $(readlink -f "$0") --plain --no-color"
return
fi
if [[ $EUID -ne 0 ]]; then
err "Installation requires root privileges"
exit 1
fi
local script_path
script_path=$(readlink -f "$0")
local motd_dir
motd_dir=$(dirname "$MOTD_TARGET")
if [[ ! -d "$motd_dir" ]]; then
mkdir -p "$motd_dir"
fi
cat > "$MOTD_TARGET" <<MOTD_EOF
#!/bin/bash
# Generated by ${SCRIPT_NAME} on $(date '+%Y-%m-%d %H:%M:%S')
# Source: ${script_path}
${script_path} --plain
MOTD_EOF
chmod 755 "$MOTD_TARGET"
log "Installed MOTD script to ${MOTD_TARGET}"
log "The MOTD will update on each login"
}
# ══════════════════════════════════════════════════════════════════════
# USAGE
# ══════════════════════════════════════════════════════════════════════
usage() {
cat <<EOF
${SCRIPT_NAME} — Generate a dynamic MOTD with system stats and health info
USAGE:
${SCRIPT_NAME} [OPTIONS]
OPTIONS:
--plain Plain text output (no box art)
--install Install as ${MOTD_TARGET} (dry-run by default)
--force Actually install (disables dry-run)
--verbose Enable debug output
--no-color Disable colored output
--help Show this help
ENVIRONMENT VARIABLES:
COLOR Color mode: auto, always, never (default: auto)
MOTD_TARGET Install target (default: ${MOTD_TARGET})
EXAMPLES:
# Display MOTD with box art
./motd-generator.sh
# Plain format for piping
./motd-generator.sh --plain --no-color
# Preview install (dry-run)
./motd-generator.sh --install
# Actually install
sudo ./motd-generator.sh --install --force
EOF
}
# ══════════════════════════════════════════════════════════════════════
# ARGUMENT PARSING
# ══════════════════════════════════════════════════════════════════════
parse_args() {
while [[ $# -gt 0 ]]; do
case "$1" in
--plain)
PLAIN="true"; shift ;;
--install)
MODE="install"; shift ;;
--force)
DRY_RUN="false"; shift ;;
--verbose)
VERBOSE="true"; shift ;;
--no-color)
COLOR="never"; shift ;;
--help|-h)
setup_colors
usage
exit 0 ;;
*)
err "Unknown option: $1"
echo "Run ${SCRIPT_NAME} --help for usage" >&2
exit 1 ;;
esac
done
}
# ══════════════════════════════════════════════════════════════════════
# MAIN
# ══════════════════════════════════════════════════════════════════════
main() {
parse_args "$@"
setup_colors
case "$MODE" in
install)
install_motd
;;
display)
if [[ "$PLAIN" == "true" ]]; then
generate_motd_plain
else
generate_motd_box
fi
;;
esac
}
main "$@"
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