download ubuntu images and keep them current

utils/download_latest_ubuntu.sh

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+#!/usr/bin/env bash
+
+set -euo pipefail
+
+DOWNLOAD_DIR="/data/ubuntu"
+mkdir -p "$DOWNLOAD_DIR"
+
+ARCH="amd64"
+
+# Supported:
+# 24.04 desktop
+# 24.04 server
+# 26.04 desktop
+# 26.04 server
+
+declare -A URLS=(
+  ["24-desktop"]="https://releases.ubuntu.com/24.04/"
+  ["24-server"]="https://releases.ubuntu.com/24.04/"
+  ["26-desktop"]="https://releases.ubuntu.com/resolute/"
+  ["26-server"]="https://releases.ubuntu.com/resolute/"
+)
+
+download_if_newer() {
+    local key="$1"
+    local base_url="${URLS[$key]}"
+
+    echo "Checking $key..."
+
+    iso_name=$(curl -fsSL "$base_url" \
+        | grep -oE 'ubuntu-[0-9.]+(-live-server|-desktop)-amd64\.iso' \
+        | sort -Vu \
+        | tail -1)
+
+    if [[ -z "$iso_name" ]]; then
+        echo "Could not determine latest ISO for $key"
+        return 1
+    fi
+
+    latest_version=$(echo "$iso_name" | grep -oE '[0-9]+(\.[0-9]+)+')
+
+    local_iso=$(find "$DOWNLOAD_DIR" -name "*$(basename "$iso_name" | sed 's/[0-9.]\+//')*" 2>/dev/null | sort | tail -1 || true)
+
+    if [[ -n "$local_iso" ]]; then
+        local_version=$(basename "$local_iso" | grep -oE '[0-9]+(\.[0-9]+)+' | head -1)
+
+        if [[ "$local_version" == "$latest_version" ]]; then
+            echo "Already up to date: $iso_name"
+            return 0
+        fi
+
+        echo "Outdated local ISO found:"
+        echo "  Local : $local_version"
+        echo "  Latest: $latest_version"
+    fi
+
+    echo "Downloading $iso_name..."
+    wget --limit-rate=4M -c -P "$DOWNLOAD_DIR" "${base_url}${iso_name}"
+
+    echo "Done."
+    echo
+}
+
+download_if_newer "24-desktop"
+download_if_newer "24-server"
+download_if_newer "26-desktop"
+download_if_newer "26-server"
+
+echo "Finished."
+