In Debian, I found many different packet versioning, do you know what they stand for?
For example :

bind9 1:9.7.3.dfsg-1~squeeze11

What do 9.7.3, dfsg-1 and squeeze11 stand for?

  • can you precise what's the problem ? is it different package version or the different number inside the name itself ?
    – Kiwy
    Feb 11, 2014 at 10:45
  • Soyy for my fuzzyness. I am trying to understand what 1: stand for, what 9.7.3 stand for, what is dfsg-1 and also squeeze11. I am quiet lost. I choose this example because it seems quite complicated. But there must be a place somewhere to understand this versionning system. Feb 11, 2014 at 10:55
  • See here: askubuntu.com/questions/330018/…
    – slm
    Feb 11, 2014 at 11:01
  • This question is basically a duplicate of the earlier asked Understanding Debian dpkg package version numbers Nov 27, 2022 at 11:12

3 Answers 3


The format of Debian version numbers is defined in the Debian policy (but it doesn't answer all your questions).

1: is an epoch. This is present when the version numbering scheme changes. For example, imagine a package that starts its life with date-based versions such as 20130123, then switches to version 1.0. The version 1.0 would be considered less than (older than) 20130123, so Debian uses 1:1.0 which is greater than 20130123 (which is implicitly 0:20130123.

Everything up to the first dash is the version number of the original source package (.orig.tar.gz file in the source distribution). 9.7.3 is the upstream version number, the version number of the original package.

Normally the original source package is the exact archive provided by the upstream project. In a few cases, the original package contains component which Debian doesn't consider free enough (documentation under GFDL is a common issue in free software projects). Debian then makes a source archive without the offending files and adds .dfsg (standing for the Debian Free Software Guidelines) to the upstream version number.

The number after the dash (here 1) is the Debian revision: the version number of the Debian packaging components: the build scripts and other meta information in the debian directory in the source archive as well as the collection of patches applied before building the package. This part is omitted for upstream Debian packages, i.e. packages (normally managed by the Debian project) where the original source archive includes all the Debian build instructions and metadata.

The ~squeeze11 suffix indicates that this package evolved from version 1 of the Debian components. ~squeeze indicates that this is a revision specifically intended for the squeeze Debian release. Different releases may need different meta information, for example to indicate library version dependencies. ~ sorts before every other character, so a 1.1 or 2 version would be considered newer than 1~squeeze11.

  • 9.7.3 stands for the version of the package you want to install aka bind9
  • dfsg does mean that Debian consider this as a real open source free software there is a long explanation here about dfsg. This is a classification of open sourceness of the content of Debian (programs, sound and pictures etc...).
  • -1 is Debian's internal numbering system for their modifications to the upstream package (per release). For each upstream release, they do a upstream_release-1, upstream_release-2 etc. is the release version of the package.
  • Finally squeeze11 and I might be wrong but is probably the name use to designate the Debian Squeeze in year 2011 but I might mistaken on this.

Hope this information help you to figure out your concerns.

  • -1 is Debian's internal numbering system for the modifications to the upstream package (per release). For each upstream release, they do a upstream_release-1,upstream_release-2, and so on. Feb 11, 2014 at 11:30

I'm sure Debian's release notes (or distribution install documentation) includes a chapter on this. If nothing else helps, look for packaging guidelines, they must tell packagers how to name their packages.

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