[NTLUG:Discuss] RHEL vs debian

[Leroy Tennison]

I couldn't agree more about Systemd (system from the devil?)  And even Ubuntu has been infected with the network management plague - for Ubuntu 18 they decided to switch to netplan which appears to be half-baked.  No warning (unless you work with the non-long-term support releases - apparently Ununtu 17 was the first to be affected) except /etc/network/interfaces has only 'lo' in it...  It could be because I selected Kubuntu but two issues: trying to return to ipupdown has produced greater than 50% packet loss across a single Ethernet cable (my system to the home router) and setting up static IP addresses is flakey: unplug a NIC and plug it back in only to find it has a DHCP address where it had a static one ...  And netplan doesn't disturb existing configurations so you will likely have remnants of a previous configuration after 'netplan apply' - at minimum remove all IP addresses before 'netplan apply'.


Now, to your question, also pay attention to file locations.  /etc/network/interfaces and interfaces.d are found under /etc/sysconfig (I believe network) as ifcfg-* files.  /etc/default files are also found under /etc/sysconfig.  Although /var/spool/cron seems to be consistent, look at where the actual tab files are located, the subdirectories under cron may be different.  The Apache directory layout is likely quite different.  Probably others but these come to mind.



-----Original Message-----
From: Christopher Cox <cjcox at acm.org>
To: NTLUG Discussion List <discuss at ntlug.org>
Sent: Wed, Sep 12, 2018 9:42 am
Subject: Re: [NTLUG:Discuss] RHEL vs debian

On 09/11/2018 11:28 PM, Ralph wrote:
> Howdy,
>   I have a lot more experience with Debian based servers than with
> RHEL.  I have always liked the way it supports upgrades for long term
> use.  But, no matter my preference, I see more companies using RHEL
> derived servers(CentOS, RHEL,, Oracle, et al).  I am applying at one
> such company and I'd like some advice.  What are a few things I need o
> study about RHEL based systems to be prepared?  I use Fedora enough to
> handle the package manager, so what else should I study?  I assume
> I'll use RHEL 7.
> Thanks,
> Ralph

It's not just systemd (systemctl, journalctl)... it's all the "*ctl" commands 
that now are a part of RHEL/CentOS.

How do you change the hostname?  hostnamectl
How do you change the timezone or other time related things? timedatectl
How do you change locale and keyboard? localectl

There's other things like

How do I join a AD domain? realm (noting, that isn't for setting up Windows shares).

Software firewalling now uses firewalld.  There's a lot to that, it's actually 
pretty interesting.  To keep things consistent, you manipulate that with 
firewall-cmd (instead of firewalctl, just keeping things consistent).

Time management drops ntpd and uses chronyd.  Ntpd was need of fixing, so glad 
to see it go.  Not saying chronyd is "perfect", but it is different (not a one 
for one ntpd replacement).

While Fedora uses dnf, RHEL/CentOS is still using yum (dnf tries to be yum like 
though command wise)

"package manager" hopefully means dnf.  If you're going to use RHEL/CentOS, 
remember that 99.999% of the time, there will be no desktop/window manager.

You'll also learn to cry as systemd dies (and it does) and leaves your system in 
an almost worthless dynamic state until it is fully rebooted (thank you 
Lennart).  This means your older RHEL/CentOS 6 platforms, while older, are much 
more reliable (sad, but true).  Interest level by Lennart and Red Hat in fixing 
this: -1,000,000 (but the "minor" problem is discussed from time to time)

Many things are still managed by editing /etc/sysconfig files.  Up to you if you 
want to learn selinux (enabled by default).  99.999% of all "secure enterprise" 
things tell you to disable it (give that some thought).  With that said, selinux 
as a very fine grained control mechanism could help make some very secure 
things... but like I said, almost every enterprise package has you disable it 
because correct setup is really "undefined" (too complex, too flexible, thus 
incomprehensible from one system to the next).

Network management has gotten worse with 7, you can use the evil NeworkManager 
or the more sane /etc/sysconfig/network-scripts approach.  Choose wisely.  IMHO, 
the authors of NetworkManager along with systemd/PulseAudio need to go to work 
for Microsoft (or anywhere as far away from Linux as possible).

Best way to learn RHEL/CentOS 7, by using it live in real world use...


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