Changing CentOS in mid-stream

Posted Dec 18, 2020 15:35 UTC (Fri) by amacater (subscriber, #790)
In reply to: Changing CentOS in mid-stream by rahulsundaram
Parent article: Changing CentOS in mid-stream

If apt doesn't do it, apt-file certainly does.

Many Red Hat users have got used to using dnf/yum - in the case of yum, that's a third party contribution to Red Hat.

dpkg -S queries at the same level as a raw rpm command

apt will do much of what you want. In some circumstances, you might want apt-file. apt-cache search foo is also useful and apt-cache is included in apt. [First came deity, then apt-get, then aptitude with a superior solver for package dependencies, then apt - the name goes back to Wed, 4 Mar 1998 19:58:33 +0000 (GMT) and the corresponding post on the debian-devel-mailing list - https://lists.debian.org/debian-devel/1998/03/msg00332.html ]

[For the curious, there was apparently a point at which Red Hat considered adopting something other than RPM right back at the beginning. Of the surviving distributions: Slackware is first, a few months later is Debian, a couple of months later is Red Hat and SUSE is an independent entity out of Jurix. And, for the purists: Debian packaging and Red Hat packaging are largely equivalent when all's said and done. A Debian package can be stripped apart using cpio and tar - an rpm requires a specific binary to do this if I remember rightly.]

Changing CentOS in mid-stream

Posted Dec 18, 2020 16:23 UTC (Fri) by rahulsundaram (subscriber, #21946) [Link] (2 responses)

> Many Red Hat users have got used to using dnf/yum - in the case of yum, that's a third party contribution to Red Hat.

That's an odd way to phrase it given that it wasn't a contribution to the company as such, just happens to be an open source project not originating from any particular vendor like the vast majority of the distribution and I am not sure why it is relevant.

In any case, for the record, Seth Vidal who was the primary developer of Yum (and a key contributor to CentOS for that matter) and was an active direct contributor to Fedora during the time that Yum became default in Fedora (and subsequently RHEL, derived from Fedora adopted it) and was an employee of Red Hat for several years while working on Yum among other things till he passed away.

Some more backstory: https://www.linuxfoundation.org/blog/2013/07/in-memoriam-...

Changing CentOS in mid-stream

Posted Dec 18, 2020 17:14 UTC (Fri) by amacater (subscriber, #790) [Link] (1 responses)

Only really that I knew that Yum concept basically came from outside Red Hat - Yellow Dog Linux, then - and is alien to fundamental RPM - it's an add on.. I was trying to demonstrate the difference between fancy front ends and the most fundamental package ordering/dependency resolving "thing" - dpkg for Debian and RPM for Red Hat and derived distributions. (And yes, RPM has had a couple more rewrites and a change to lower case: dpkg was rewritten a few times in 1994 but is essentially the same since then).

There's not a lot to choose between them, as I wrote: I've had someone complain at me that it was harder to check signatures of packages in Debian because Debian signs the package manifest - but, meh, apt[-get|itude] checks that for you automatically and will whinge at you if the package list is out of date.

Changing CentOS in mid-stream

Posted Dec 18, 2020 18:29 UTC (Fri) by rahulsundaram (subscriber, #21946) [Link]

> Only really that I knew that Yum concept basically came from outside Red Hat - Yellow Dog Linux, then - and is alien to fundamental RPM - it's an add on

To be more accurate, YUP is from Yellow Dog. Yum although it shares some history with YUP is significantly different and originated from Duke university with Seth Vidal as the primary developer. Technically, similar to dpkg vs Apt. As you noted, just a higher level tool - I consider this as a package manager vs higher level dependency resolver (in Dnf - there are multiple libraries that handle different aspects and the resolver logic is part of libsolv - Originating from Opensuse). In Debian, there have been different resolvers in the past (Smart for example - Canonical at one point was considering making it the default resolver for Ubuntu).

Changing CentOS in mid-stream

Posted Dec 18, 2020 22:53 UTC (Fri) by Wol (subscriber, #4433) [Link]

> a couple of months later is Red Hat and SUSE is an independent entity out of Jurix.

If I remember my SuSE history correctly, it started a few months before Red Hat as a Slackware derivative. Then they rebased it on Jurix, before starting to use rpm as their packaging solution.

Cheers,
Wol

Changing CentOS in mid-stream

Posted Dec 29, 2020 16:06 UTC (Tue) by jwilk (subscriber, #63328) [Link] (1 responses)

> A Debian package can be stripped apart using cpio and tar

It's ar, not cpio: https://manpages.debian.org/deb.5

Changing CentOS in mid-stream

Posted Dec 30, 2020 18:23 UTC (Wed) by anselm (subscriber, #2796) [Link]

RPM packages are basically cpio archives with a header attached in front. There's an rpm2cpio program that will remove the header so the rest can be fed to cpio.