I have some software packages customised for Ubuntu 10.04, 10.10 and 12.10, but now I have to install them on Debian Squeeze. I have been unable to Google for a mapping between specific Ubuntu and Debian versions. Can someone here help?
Specifically I want to know which Ubuntu version corresponds to Debian Squeeze.
You can find the Debian version on which your Ubuntu version is based in the file /etc/debian_version
| Ubuntu Version | Ubuntu Codename | /etc/debian_version | Debian Version |
|---|---|---|---|
| 25.04 | Plucky Puffin | trixie/sid | 13 |
| 24.10 | Oracular Oriole | trixie/sid | 13 |
| 24.04 LTS | Noble Numbat | trixie/sid | 13 |
| 23.10 | Mantic Minotaur | trixie/sid | 13 |
| 23.04 | Lunar Lobster | bookworm/sid | 12 |
| 22.10 | Kinetic Kudu | bookworm/sid | 12 |
| 22.04 LTS | Jammy Jellyfish | bookworm/sid | 12 |
| 21.10 | Impish Indri | bullseye/sid | 11 |
| 21.04 | Hirsute Hippo | bullseye/sid | 11 |
| 20.10 | Groovy Gorilla | bullseye/sid | 11 |
| 20.04 LTS | Focal Fossa | bullseye/sid | 11 |
| 19.10 | Eoan Ermine | buster/sid | 10 |
| 19.04 | Disco Dingo | buster/sid | 10 |
| 18.10 | Cosmic Cuttlefish | buster/sid | 10 |
| 18.04 LTS | Bionic Beaver | buster/sid | 10 |
| 17.10 | Artful Aardvark | stretch/sid | 9 |
| 17.04 | Zesty Zapus | stretch/sid | 9 |
| 16.10 | Yakkety Yak | stretch/sid | 9 |
| 16.04 LTS | Xenial Xerus | stretch/sid | 9 |
| 15.10 | Wily Werewolf | jessie/sid | 8 |
| 15.04 | Vivid Vervet | jessie/sid | 8 |
| 14.10 | Utopic Unicorn | jessie/sid | 8 |
| 14.04 LTS | Trusty Tahr | jessie/sid | 8 |
| 13.10 | Saucy Salamander | wheezy/sid | 7 |
| 13.04 | Raring Ringtail | wheezy/sid | 7 |
| 12.10 | Quantal Quetzal | wheezy/sid | 7 |
| 12.04 LTS | Precise Pangolin | wheezy/sid | 7 |
| 11.10 | Oneiric Ocelot | wheezy/sid | 7 |
| 11.04 | Natty Narwhal | squeeze/sid | 6 |
| 10.10 | Maverick Meerkat | squeeze/sid | 6 |
| 10.04 LTS | Lucid Lynx | squeeze/sid | 6 |
Sid is the development distribution of Debian. That's how, for example, Ubuntu 20.04, released in April 2020, can be based on Debian 11 "Bullseye", which was released in August 2021.
You can find out the contents of the file without installing an entire system by viewing the sources for the package basefiles on Launchpad.
Unfortunately there is no direct mapping /etc/debian_version as mentioned in Jacob's answer gives a rough idea but it only really reflects one package and said package is a package that is locally modified in Ubuntu so won't be automatically pulled in from Debian.
In particular Ubuntu is often ahead of Debian on core packages like libc6. Trying to install a package built on Ubuntu on a contemporary version of Debian is likely to end up with version errors on libc6.
According to https://superuser.com/questions/407745/wrong-libc6-version-in-debian-squeeze-can-i-go-back Debian squeeze had libc6 2.11 . According to http://web.archive.org/web/20110705212424/http://packages.ubuntu.com/search?keywords=libc6 ubuntu 10.04 lucid also had libc6 2.11 . So the packages for 10.4 lucid are IMO the most likely to work on Squeeze.
Depending on what other libraries your program needs you may well find that a specific build for Debian squeeze is needed.
In addition to what was said,
Note that a package from an APT-based distribution (e.g. Ubuntu) should not be installed in another APT-based distribution (e.g. Debian), as default. Also vice-versa.
This question is still useful if you are a package maintainer, but not for end-users. End-users should just don't install packages from alien distributions.
When you need cross-platform packages, see instead these solutions that were designed for that purpose:
Again, apt packages are not designed to be cross-distribution and should not be used for that purpose. That is, if you are interested in avoiding to create Frankenstein.
Explanations:
https://wiki.debian.org/DontBreakDebian
https://wiki.debian.org/DontBreakDebian#Don.27t_make_a_FrankenDebian
