[NTLUG:Discuss] RHEL vs debian

[Christopher Cox]

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...