lxs/tools/welcome-message.sh

#!/bin/bash

# LXS - Welcome message (MOTD)
# Description: View, edit, or reset the SSH login welcome message (/etc/motd)
# Author: LXS
# Date: 2025

# Load LXS common library (colors, separator, run_spinner, loggers, helpers)
LXS_RAW_BASE="${LXS_RAW_BASE:-https://git.hyko.cx/hykocx/lxs/raw/branch/main}"
_lib=$(curl -fsSL "${LXS_RAW_BASE}/lib/common.sh") || { echo "Failed to fetch lib/common.sh" >&2; exit 1; }
eval "$_lib"
unset _lib
export LXS_LOG_FILE="/tmp/lxs_welcome_message.log"

require_root "$0" "$@"

set -u

MOTD_FILE="/etc/motd"
BACKUP_FILE="/etc/motd.lxs.bak"
DYNAMIC_DIR="/etc/update-motd.d"

# ═══════════════════════════════════════════════════════════════════════════
# Arguments
# ═══════════════════════════════════════════════════════════════════════════

ACTION=""
TEXT=""
FROM_FILE=""

while [ $# -gt 0 ]; do
    case "$1" in
        view|--view|show|--show)   ACTION="view" ;;
        set|--set|edit|--edit)     ACTION="set" ;;
        reset|--reset)             ACTION="reset" ;;
        --text)                    shift; TEXT=${1:-} ;;
        --text=*)                  TEXT="${1#*=}" ;;
        --from-file)               shift; FROM_FILE=${1:-} ;;
        --from-file=*)             FROM_FILE="${1#*=}" ;;
        -h|--help)
            cat <<EOF
Usage: welcome-message.sh [action] [options]

Actions:
  view                 Show the current welcome message
  set                  Set a new welcome message (see source options below)
  reset                Clear the welcome message (a backup is kept)

Source options for 'set' (mutually exclusive):
  --text "..."         Use the given string as the new message
  --from-file PATH     Read the new message from PATH
  (none)               Open an interactive editor (\$EDITOR or nano/vi)

  -h, --help           Show this help

With no action, an interactive menu is shown.

The welcome message lives in ${MOTD_FILE}.
On Ubuntu, dynamic MOTD scripts in ${DYNAMIC_DIR} also contribute to the
banner shown at login — those are not modified by this tool.
EOF
            exit 0
            ;;
        *)
            echo -e "${RED}Unknown option: $1${NC}" >&2
            exit 1
            ;;
    esac
    shift
done

if [ -n "$TEXT" ] && [ -n "$FROM_FILE" ]; then
    err "--text and --from-file are mutually exclusive"
    exit 1
fi

# ═══════════════════════════════════════════════════════════════════════════
# Helpers
# ═══════════════════════════════════════════════════════════════════════════

view_motd() {
    echo -e "${WHITE}${BOLD}Current welcome message${NC} ${GRAY}(${MOTD_FILE})${NC}"
    show_separator
    if [ ! -s "$MOTD_FILE" ]; then
        echo -e "${GRAY}(empty)${NC}"
    else
        cat "$MOTD_FILE"
    fi
    show_separator

    if [ -d "$DYNAMIC_DIR" ] && compgen -G "${DYNAMIC_DIR}/*" >/dev/null; then
        echo ""
        warn "Dynamic MOTD scripts are present in ${DYNAMIC_DIR}:"
        find "$DYNAMIC_DIR" -maxdepth 1 -type f -executable -printf '  • %f\n' | sort
        echo -e "${GRAY}These run at login and add to the banner.${NC}"
    fi
}

backup_motd() {
    [ -f "$MOTD_FILE" ] || return 0
    cp -a "$MOTD_FILE" "$BACKUP_FILE"
    info "Previous message backed up to ${BACKUP_FILE}"
}

write_motd() {
    local src=$1
    backup_motd
    install -m 644 "$src" "$MOTD_FILE"
    ok "Welcome message updated"
    echo ""
    view_motd
}

set_from_text() {
    local tmp
    tmp=$(mktemp /tmp/lxs.motd.XXXXXX) || { err "mktemp failed"; return 1; }
    # Preserve embedded newlines; ensure a trailing newline.
    printf '%s\n' "$1" > "$tmp"
    write_motd "$tmp"
    rm -f "$tmp"
}

set_from_file() {
    local src=$1
    if [ ! -r "$src" ]; then
        err "Cannot read file: ${src}"
        return 1
    fi
    write_motd "$src"
}

set_interactive() {
    local editor=${EDITOR:-}
    if [ -z "$editor" ]; then
        if command -v nano >/dev/null 2>&1; then editor="nano"
        elif command -v vi >/dev/null 2>&1; then editor="vi"
        else
            err "No editor found (\$EDITOR unset; nano/vi missing). Use --text or --from-file."
            return 1
        fi
    fi

    local tmp
    tmp=$(mktemp /tmp/lxs.motd.XXXXXX) || { err "mktemp failed"; return 1; }
    [ -s "$MOTD_FILE" ] && cat "$MOTD_FILE" > "$tmp"

    info "Opening ${editor}... save and exit to apply, leave empty to cancel."
    "$editor" "$tmp"

    if [ ! -s "$tmp" ]; then
        warn "Empty content — change cancelled."
        rm -f "$tmp"
        return 0
    fi

    write_motd "$tmp"
    rm -f "$tmp"
}

reset_motd() {
    if [ ! -s "$MOTD_FILE" ]; then
        info "Welcome message is already empty."
        return 0
    fi
    backup_motd
    : > "$MOTD_FILE"
    chmod 644 "$MOTD_FILE"
    ok "Welcome message cleared"
}

# ═══════════════════════════════════════════════════════════════════════════
# Menu (when no action is given on the CLI)
# ═══════════════════════════════════════════════════════════════════════════

if [ -z "$ACTION" ]; then
    echo -e "${WHITE}${BOLD}LXS - Welcome message${NC}"
    show_separator
    echo -e "  ${CYAN}[1]${NC} View current message"
    echo -e "  ${GREEN}[2]${NC} Set a new message"
    echo -e "  ${YELLOW}[3]${NC} Reset (clear) the message"
    echo -e "  ${RED}[0]${NC} Cancel"
    echo ""
    echo -e -n "${BOLD}Choice [0-3]: ${NC}"
    read -r choice
    case "$choice" in
        1) ACTION="view" ;;
        2) ACTION="set" ;;
        3) ACTION="reset" ;;
        0|"") info "Cancelled."; exit 0 ;;
        *) err "Invalid option."; exit 1 ;;
    esac
fi

case "$ACTION" in
    view)  view_motd ;;
    set)
        if [ -n "$TEXT" ];          then set_from_text "$TEXT"
        elif [ -n "$FROM_FILE" ];   then set_from_file "$FROM_FILE"
        else                             set_interactive
        fi
        ;;
    reset) reset_motd ;;
esac