How does yum compare versions?

Question

We have a web app we package into an RPM. We have a problem with the version field of the RPM.

Let's say we have installed our rpm: foo-2.1.0.007

007 is our build number.

Now when we try to install a newer rpm, foo-2.1.0.010, yum says "There's nothing to update".

When I've remade the RPMs, but removed the leading zeroes, the problem was solved:

foo-2.1.0.7

foo-2.1.0.10

According to this link each segment of the version is compared as an integer, but practice shows otherwise.

So my question is: What is the version comparison algorithm for RPM and why leading zeroes interfere?

Answer 1

Yum just asks rpm to compare them. You can install rpmdevtools, and you then use:

% rpmdev-vercmp foo-2.1.0.010 foo-2.1.0.007
0:foo-2.1.0.010 is newer

...which is what you'd expect. Unless you have an epoch in the 007 package, I'm not sure why you are getting a different answer. What version of rpm do you have? What does vercmp say for you?