[Fedora-packaging] Guidelines and epochs

Fernando Nasser fnasser at redhat.com
Mon Jan 8 14:41:56 UTC 2007


I'd also change the format to "the smallest possible integer".  Epoch's 
are already a pain as small integers like "1" or "2".  Imagine as 
"anything that is suited for the version/release tags is also suited here".

Also, I have mixed feeling about this.  As there are some packages that 
for historic reasons had to have their Epoch bumped, it is very easy to 
forget to add the "1:" in front of the dependency versions.  The other 
thing is that RPMs deal with "EVR" where "E" stands for "Epoch", so I 
wonder if the right thing wouldn't be to make that clear by having the 
Epoch, Version and Release tags all there, always (even if zero).

Anyway, before it would be a problem to make this change as RPM had a 
bug that would not correctly equate "Epoch: 0" with a version dependency 
lacking the leading ":0", but I believe this has been fixed several RPM 
releases ago (right Paul?), so it shouldn't be a problem now.  But 
please allow a release or two to enforce this so we can propagate this 
rule upstream to the packages we import (leaving it as a recommendation 
only for FC7 for instance).


Axel Thimm wrote:
> Seems like it isn't really clear that we want packagers to evoid
> epochs like the devil. There are some situations that require epochs,
> when there is no other way to undo versioning and, of course, when
> there were epochs to start with.
> Currently epochs are only mentioned under the Requires section:
>> Second, the Epoch must be listed when adding a versioned dependency
>> to achieve robust epoch-version-release comparison. A quick way to
>> check the Epoch of package foo is to run:
> I'd like to clarify that so that it refers only to non-zero epochs to
> avoid people adding "0:" upfront of every mentioned version(-release),
> e.g. change "the Epoch" against "a non-zero Epoch"
> Then I'd like to have somewhere a recommendation that epochs should be
> avoided as much as possible. This seems to belong to
> Packaging/NamingGuidelines, where epochs seem to have been left off
> (probably deliberately to not lead people into temptation). How about
>> Package Epoch
>> epochs are generally to be avoided. They provide a last-resort
>> mechanism to override package version and release, but are more
>> trouble than they are worth while. If you realy have to use an epoch
>> you MUST use a simple integer (technically anything that is suited
>> for the version/release tags is also suited here). Make sure you
>> explore all other possiblities before deciding to use epochs.
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