# Build with a baseline OS Choose a Debian or Ubuntu baseline and build a package bundle without capturing a snapshot. Source: https://debark.dev/docs/get-started/no-target-machine --- A **baseline OS** describes a stock Debian or Ubuntu installation: its release, installation variant, and architecture. Choose one on the online computer to build without taking a snapshot of the offline machine. Use a baseline when you know the target’s standard installation or cannot access it yet. A snapshot is more accurate for a customized machine because it records its actual packages and apt settings. ## Choose a baseline Use the [baseline OS list](/docs/get-started/supported-systems#baseline-os-list) to find exact IDs for each release and variant, and the [architecture table](/docs/get-started/supported-systems#target-architecture) to choose the value for `--arch`. List the choices in your installed CLI: ```bash debark snapshot list-bases ``` The built-in releases are Debian 12 and 13, and Ubuntu 22.04, 24.04, and 26.04. Each has three variants: | Variant | What it assumes is already installed | | --------- | ---------------------------------------------------- | | `minimal` | The base system and apt. | | `server` | The base system and a standard server package set. | | `desktop` | The base system and the default desktop environment. | An ID combines the distribution, release, and variant: `ubuntu:24.04/minimal`. Omitting the variant selects `minimal`. These choices describe the target; they do not install an operating system. Choose the variant that matches the machine. A desktop baseline on a minimal machine can leave needed packages out of the bundle. Use `--arch amd64` or `--arch arm64` to select the target architecture. If you can access the target, `dpkg --print-architecture` reports it. Without `--arch`, the CLI uses the builder’s architecture. ## Build on the online computer You need the [CLI](/docs/get-started/installation) and a working [build backend](/docs/concepts/backends). Create a signing key once, or reuse an existing one: ```bash debark keygen --out operator.key ``` For example, prepare `jq` for Ubuntu 24.04 minimal on amd64: ```bash debark build --base ubuntu:24.04/minimal --arch amd64 \ --out ./bundle --sign operator.key jq ``` No target snapshot file is needed. Debark uses the baseline’s package assumptions to work out the downloads, then creates an ordinary package bundle. Use either `--base` or `--snapshot`, never both. You can also use package lists, vendor .deb files, and the other [build options](/docs/guides/building-a-bundle). ## Choose through interactive prompts If you prefer questions to flags: ```bash debark build --interactive ``` When asked whether you have a target snapshot, answer no. Choose the distribution, release, variant, and architecture, then enter your packages and build options. The [interactive CLI guide](/docs/get-started/interactive) explains the prompts and saved package list. ## Save a baseline for reuse You can optionally save the generated baseline as a snapshot file: ```bash debark snapshot from-base ubuntu:24.04/minimal \ --arch amd64 --out base.tar.zst ``` Then pass `--snapshot base.tar.zst` in later builds. It still describes an assumed baseline, not a captured machine. This extra step is not needed for `build --base`. To choose and save a baseline through prompts, run: ```bash debark snapshot from-base --interactive ``` ## Check the bundle on the target Follow the [quickstart](/docs/get-started/quickstart#3-transfer-the-bundle-and-public-key) to transfer the bundle and provide the public key separately. Preview the installation: ```bash debark install ./bundle --key operator.pub --status ``` The report compares the baseline’s assumptions with the real machine and warns if assumed packages are missing. Review those warnings before installing. If the baseline does not fit, capture a snapshot of the target and rebuild. Baseline builds have less end-to-end testing than builds from captured snapshots.