[CentOS] more recent perl version?

Wed May 24 14:23:04 UTC 2017
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On Wed, May 24, 2017 8:46 am, Warren Young wrote:
> On May 24, 2017, at 6:02 AM, hw <hw at gc-24.de> wrote:
>> Warren Young schrieb:
>>> CentOS 5 just left supported status, which shipped Perl 5.8.8 from
>>> first release to last
>> Living in the past seldwhen is a good idea.
> I don’t propose to teach you about my problems — they are, after all,
> mine, and I’m coping with them quite well, thank you — but I’ll give
> you a glimpse into someone else’s as a lesson: the San Francisco Bay
> Area Rapid Transit System was still running on PDP-8s as of several years
> ago, and may still be doing so.

Warren, thanks a lot for this long and extremely instructive post!! I'm
with you on all counts.


> As I understand it, they were using a modified PDP-8/e, which is 1970
> tech.  Note that I didn’t say “1970’s.”  I mean the year nineteen
> hundred and seventy, A.D.  The PDP-8/e is just an enhanced version of the
> original PDP-8 from 1965, which is itself not a huge departure from the
> PDP-5, from 1963.
> And you know what?  The PDP-8/e is still well suited to the task.  Trains
> haven’t changed that much in the intervening decades, and the
> construction techniques used by that era of computer mean it’s still
> repairable with little more than a soldering iron.
> We have 40-cent microcontrollers with equivalent computing power to a
> PDP-8/e today that run on far less power, but you’d have to pile up a
> bunch of I/O interfacing in front of them to make it as electrically
> capable and robust as a PDP-8/e, and you’d have to re-develop all the
> software, too.
> The modern tendency would not be to use one of those 40-cent micros, it
> would instead be to put a gigahertz class Linux PC in its place, with all
> the concomitant risks.
> Try getting a modern Internet worm into a PDP-8!  Good luck not blowing
> the 4k word field boundary.
>>> If this sort of stance seems risible to you, you probably shouldn’t
>>> be using CentOS.  This is what distinguishes a “stable” type of OS
>>> from a “bleeding edge” one.
>> When a version of a software has been released 20 years ago,
> Eleven: https://dev.perl.org/perl5/news/2006/perl-5.8.8.html
> …which makes it younger than the C89 standard some still stick to over
> in C land.  And younger than C99.  And younger than C++-98.  And C++-93.
> By your lights, the C/C++ world is positive decrepit for not immediately
> tossing everything and insisting on C11 and C++-14.
>> that doesn´t mean it´s more stable than a version of that
>> software which is being released today.
> Actually, it does, provided it’s still being maintained, as Perl 5.8.8
> was up to a few months ago.  Software that gets no new features also gets
> no new bugs.  Therefore, the overall bug count can only go down.
> The distinction you may be looking for is that there is a fine line
> between “stable” and “moribund.”  RHEL/CentOS rides that line much
> closer than some other OSes, but it actively stays on the good side of the
> line.
> After that end-of-support date, sometimes all it takes to slip over to the
> bad side of the line is a new exploit or similar, but decades-old exploit
> targets are very rare.
> More commonly, something changes in the environment to make the old
> software unsuitable, as happened with BIND 4 and Apache 1.3.  You
> couldn’t drag either of those forward into the modern world without
> major rework, so people running on them were forced to transition.
> I don’t see that happening with Perl 5.8.  It was an uncommonly good
> release of a language that was already quite stable by that point.  It is,
> after all, the fourth major version after Perl 5.0.  You’d *expect* it
> to be stable by that point.
> The only question then, is whether you can live without the new features.
> I can.
>> what about the bug fixes?
> Red Hat was backporting them up until a few months ago.
> Now we just get to see how fast it bit-rots without Red Hat’s support.
> I don’t expect it to do so quickly.
>> Feature "signatures" is not supported by Perl 5.16.3 at …
> Again, see the docs:
>     https://perldoc.perl.org/perlsub.html#Signatures
> I note that this feature is still marked experimental and subject to
> removal.
> …And you’re lecturing me about stability?
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247