From Fedora Project Wiki

FC6 Distribution Tags in Red Hat Enterprise Linux 5


Some Red Hat Enterprise Linux 5 RPMs have .fc6 in their name. Why is this happening, and what does it mean?


An RPM's spec file contains a place for an optional distribution tag. This tag is used so that a single spec file can build a package for multiple distributions, because sometimes a package's dependencies will be different from one distribution to another.

For Fedora Core 6, the distribution tag is .fc6 and for Red Hat Enterprise Linux 5, the distribution tag is .el5

An RPM with one of these distribution tags was initially built for that particular distribution.

Fedora Core 6 served as the upstream for Red Hat Enterprise Linux 5. From the RPM building perspective, both distributions share the same version of glibc and gcc. Therefore, some packages that were built and tested for the Fedora Core 6 release did not need to be rebuilt for the Red Hat Enterprise Linux 5 release.

In general terms, when you build an RPM, there are two things you have to test: 1. The integrity of that one specific RPM. 2. The functionality of that RPM when placed in a group with all the other RPMs in a distribution.

By maintaining these packages exactly as they were initially created, and taking them from Fedora Core 6 directly into Red Hat Enterprise Linux 5, the validation and testing work that was done to meet condition (1) above did not have to be repeated, and more effort could be focused on the testing to meet condition (2).

Looking at the Red Hat Enterprise Linux 5 Client (x86) release candidate, there are 187 packages out of 1507 total that have the .fc6 tag. The Server version of that same release candidate has 252 packages with the .fc6 tag out of 2108.

Further technical reading: