CentOS 8: What Changed (regular UNIX Admin Commands)?

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Hello Experts!

I’m sure many of you run CentOS for some time already.

My question is: is there some place that lists which of the most often used sysadmin commands are gone and what are replacements for them. Or what else one needs to do after successful installation. (in the past it was process accounting that was not enabled by default, but which gives you quite some handle in investigating compromise).

I just tried quite ordinaly command of freshly installed CentOS 8:

last

and got an error:

last: (default utx db): No such file or directory

I realize that it could be just me, and I’ll cope with that myself one way or another but this one prompted me to ask everybody: Is there anything I can read so I can learn what differenmt to expect on CentOS 8
from, say, CentOS 7?

Thanks. Valeri

++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++

15 thoughts on - CentOS 8: What Changed (regular UNIX Admin Commands)?

  • Huh. When I run it I got

    [root@localhost ~]# last root pts/0 192.168.1.15 Sat Oct 19 15:42 still logged in reboot system boot 4.18.0-80.11.2.e Fri Oct 18 09:39 still running root pts/1 192.168.1.15 Thu Oct 17 14:16 – 09:38 (19:22)
    smooge pts/1 192.168.1.15 Fri Oct 4 18:14 – 13:24 (12+19:10)
    smooge pts/1 192.168.1.15 Fri Oct 4 09:02 – 09:09 (00:06)
    smooge pts/1 192.168.1.15 Thu Oct 3 16:31 – 16:46 (00:14)
    smooge pts/2 192.168.1.15 Mon Sep 23 17:23 – 09:05 (15:41)
    smooge pts/1 192.168.1.15 Sat Sep 21 14:45 – 10:36 (5+19:51)
    smooge pts/1 192.168.1.15 Thu Sep 19 17:04 – 17:05 (00:01)
    smooge pts/1 192.168.1.15 Mon Sep 16 13:06 – 17:02 (03:55)
    smooge tty2 tty2 Thu Sep 12 12:43 – down (35+20:55)
    reboot system boot 4.18.0-80.el8.x8 Thu Sep 12 12:33 – 09:38 (35+21:05)

    In el7 it used to be in this package:
    [smooge@batcave01 ansible (master)]$ rpm -qf /usr/bin/last sysvinit-tools-2.88-14.dsf.el7.x86_64

    And in el8 it is in
    [root@localhost ~]# rpm -qf /usr/bin/last util-linux-2.32.1-8.el8.x86_64

    The wtmp file is owned by
    [root@localhost ~]# rpm -qf /var/log/wtmp systemd-239-13.el8_0.5.x86_64

    However as you can tell from above this system has been installed for a bit so I am guessing whatever creates wtmp hasn’t happened?

  • Indeed, as I suspected, it was just me. Really stupid thing: I shuffled two hostnames (one was freshly installed CentOS 8 machine, another was jail inside some FreeBSD machine…). Puzzle solved, but thanks to that I’m reading RedHat’s document about what’s new in RedHat 8 compared to
    7, – Thank you, Leon, for link in your reply!

    Valeri

  • Saw your later response that the problem was solved but this is an interesting question that deserves an answer (and not just what changed in RHEL8).  As an example, I’m used to ifconfig and route but keep getting reminded that these commands are now deprecated and “ip” should be used instead.  Likewise for using dnf instead of yum, systemctl instead of service, firewallcmd instead of iptables, etc. I wonder how many shell scripts there are “out there” that folks have written or accumulated over the years and which now need to be updated before deprecated becomes no longer available?  Or, like using iptables instead of firewallcmd, may cause something very different than what is expected.

    Anyone know of any resource out there that might provide such documentation?

    Cheers, Dave

    —
    “They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty.”

    — Benjamin Franklin

  • I think that the deprecation of ifconfig and route was started before RHEL-7 came out.. and yet I just can’t get used to them.

  • The ip commands have been around since CentOS 6 if not earlier. you can do things with them that you can’t do with ifconfig, such as setup policy routing rule sets..

  • Once upon a time, Stephen John Smoogen said:

    I’ve started using “ip” for more things lately… partly because I’m lazy, and once I learned the commands can be abbreviated, I can type less. :)

    ifconfig -> ip l (or maybe ip -s l if I want counters)
    route -> ip r arp -> ip n

    I’m also getting more used to nmcli for connection and configuration management (which also allows abbreviation – wooo for laziness!).

    firewalld is not really the same thing as iptables though; it’s more of a management layer on top of just writing raw rules. One big issue I
    have though is that firewalld always sets up kernel connection state tracking, which is not a good thing for some uses (high-traffic DNS
    servers for example).

    The bigger change there is switching from iptables to nftables – while you can keep using the iptables command and language (there’s a translation), to get the most out of it, you have to learn the nft command and language (which is different). I’ve barely scratched the surface on that one.

  • which makes them harder to learn…

    Unix philosophy: small programs, each of which does one thing well.

  • But we know it: Linux != UNIX

    Incidentally, reading new RedHat 8 guide (RedHat “diff 8 7”) I’ve notices quite pleasing thing: they shift toward similarity with some UNIXes, namely: base system, and addons.

    Valeri

  • Smooge, that is because you are OLD :)

    Actually .. i have the same issues .. probably for the same reason :)

  • With the case of DNF and Yum, the RHEL team put in considerable work into making sure that the new DNF-based ‘yum’ command is a drop-in replacement for the vast majority of those scripts.

  • I think that the complaint should be that yum/dnf are not even what a real Unix would use. We should only get giant UUencoded patch files
    (and even then it may really just need to be tapes)

  • They did so well, that I didn’t even notice anything changed – no complaints from my “automated” update facility. I only learned about this change from “diff {RedHat} 8 7” document.

    This reminds me what I used to say about my sysadmin job: My job is like that of a plumber: if I do it right, no one will notice that I exist; if I do it wrong, everybody gets … you know what.

    Well done, RedHat!

    Valeri

    —
    ++++++++++++++++++++++++++++++++++++++++
    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247
    ++++++++++++++++++++++++++++++++++++++++

  • One major change is that the Firewalld in el8 doesn’t use “iptables” rules (netfilter) but instead “nft” rules (nftables).

    —
    Jonathan Billings