When I do apt-show-versions samba on my Debian machine, I get something like

samba:amd64/buster 2:4.9.5+dfsg-5+deb10u1 uptodate

Comparing this to the samba versions, which you can find at the official sources, I would assume, that samba 4.9.5 is installed. But what are the other numbers and letters?

My guess is that these indicate Debian specific modifications. But would like to understand how to read them and what they mean. Especially if these change but the "base"-version (here 4.9.5) stays the same.


1 Answer 1


The full description is given in Debian Policy; in this specific version:

  • 2 (before the :) is the epoch, basically a Debian-specific counter which is used when the main version number “goes back”
  • 4.9.5 is the upstream version, matching Samba 4.9.5
  • +dfsg is a suffix indicating that the upstream sources were repackaged to remove DFSG-non-free content (parts of the source code which don’t meet the Debian Free Software Guidelines)
  • 5 (after the -) is the revision of the package; this is incremented when changes are made to the packaging, without changing the upstream version
  • +deb10u1 is a suffix indicating that the packaging was updated for Debian 10, i.e. as a stable update after Debian 10 was released, and that this is the first such update.

Epochs rarely change, and only in association with an upstream version change. The suffixes change when the packaging changes, without an upstream version change; the first suffix (5 here) changes during the development of the next Debian release, and the second (deb10u1 here) changes for updated to a specific Debian release (for a security update or an important bug fix in a point release).

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