# PLONK

**PLONK** stands for:

> **PLONK Leaves Only Needed Kernels**

It is a small Debian-oriented shell script used to list, simulate and purge old Linux kernel packages.

In short:

> old kernels go plonk.

## What it does

PLONK helps keeping Debian systems clean by removing old kernel packages while preserving the kernels that are still needed.

It can:

* list old installed kernel packages;
* list kernel packages left in `rc` state;
* simulate the purge operation before doing anything;
* purge old kernel packages;
* keep a configurable number of installed kernels;
* always keep the currently running kernel;
* avoid removing Debian kernel meta-packages such as `linux-image-amd64`.

## Why

Debian systems can accumulate old kernel packages over time, especially on long-lived servers or frequently updated machines.

Sometimes old kernels are already removed but still appear in `dpkg` output with `rc` status, meaning that only residual configuration files are left.

PLONK tries to clean both cases in a conservative way.

## Requirements

PLONK requires:

* Debian;
* `bash`;
* `apt-get`;
* `dpkg-query`;
* root privileges when actually removing packages.

It is mainly written and tested with Debian in mind.

## Usage

```bash
plonk [option]
```

Available options:

```text
-l | --list      : list old kernel packages
-n | --dry-run   : simulate old kernel packages removal
-r | --remove    : remove old kernel packages
-k | --keep NUM  : number of kernels to keep
-y | --yes       : assume yes when removing packages
-h | --help      : show help and exit
```

## Examples

List old kernel packages and residual `rc` packages:

```bash
./plonk --list
```

Simulate the purge operation:

```bash
./plonk --dry-run
```

Remove old kernel packages:

```bash
sudo ./plonk --remove
```

Remove old kernel packages and keep three installed kernels:

```bash
sudo ./plonk --remove --keep 3
```

Remove old kernel packages without confirmation:

```bash
sudo ./plonk --remove --yes
```

## Recommended workflow

Before removing anything, always run:

```bash
./plonk --list
```

Then run:

```bash
./plonk --dry-run
```

Only after reviewing the output, run:

```bash
sudo ./plonk --remove
```

On production servers, remote systems or machines where rollback matters, keeping more than the default number of kernels is recommended:

```bash
sudo ./plonk --remove --keep 3
```

## About `rc` packages

In `dpkg` output, packages in `rc` state are already removed, but their configuration files are still present.

Example:

```text
rc  linux-image-6.1.0-38-amd64  6.1.147-1  amd64  Linux 6.1 for 64-bit PCs
```

PLONK can purge those residual packages too.

## Safety notes

PLONK is intentionally conservative.

It always keeps:

* the currently running kernel;
* at least one additional installed kernel by default;
* the related Debian kernel ABI packages;
* Debian kernel meta-packages.

Still, kernel removal can be risky. Always check the dry-run output before purging packages.

## Install

Clone the repository:

```bash
git clone <repo-url>
cd plonk
```

Make the script executable:

```bash
chmod +x plonk
```

Optionally install it system-wide:

```bash
sudo install -m 0755 plonk /usr/local/sbin/plonk
```

Then run:

```bash
plonk --help
```

## Name

`plonk` is both:

```text
PLONK Leaves Only Needed Kernels
```

and the sound old kernels make when they finally disappear down the drain.

## License

* GPL-3.0-or-later.