# Debian Release Cycle

Debian has multiple releases at different maturity levels: Stable, Testing, and Unstable.

## Release Names

- **Stable (current)** — thoroughly tested, conservative updates, security fixes for ~5 years
- **Testing (next)** — receives new package versions daily, tested less, becomes stable every 2 years
- **Unstable/Sid** — bleeding-edge, permanent, breaks frequently, for developers only
- **Old Stable** — previous stable release, gets security updates for ~1 year after new stable

Current (as of 2024):
- Stable: Bookworm (12)
- Testing: Trixie (13)
- Unstable: Sid (permanent)

## Check Current Release

```bash
cat /etc/os-release
cat /etc/debian_version
lsb_release -a
```

## Switching Releases

To upgrade from Stable to Testing:

```bash
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
sudo sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
sudo apt update
sudo apt full-upgrade
```

Then reboot:

```bash
sudo reboot
```

## Upgrade Path

- Stable → Testing: possible, expect breakage
- Testing → Unstable: possible, expect major breakage
- Never downgrade: once upgraded, can only upgrade further

## Release Timeline

Major releases every ~2 years. Typical cycle:
1. **Testing** — development, ~1 year
2. **Freeze** — bug fixes only, feature freeze
3. **Release** — becomes new Stable

## Security Updates

- **Stable**: Long-term support, frequent security updates
- **Testing**: Less frequent security updates
- **Unstable**: No guarantees, for developers

Production servers should run Stable. Never Unstable.

## Release Schedule

See Debian release info:

```bash
https://wiki.debian.org/DebianReleases
```

Release dates are announced well in advance but are "when ready," not fixed.

## Distribution Codenames

Old to new:
- Wheezy (7, EOL)
- Jessie (8, EOL)
- Stretch (9, EOL)
- Buster (10, old-stable)
- Bullseye (11, old-stable)
- Bookworm (12, stable)
- Trixie (13, testing)
- Sid (unstable)

## Tips for Stability

- Use Stable for production
- Use Testing only if you need newer packages
- Use Unstable only for development
- Run `apt full-upgrade` before critical work (never during)
- Backup before major upgrades
- Read release notes before upgrading