NewLinuxInfo

From TheBestLinux.com
Jump to navigation Jump to search

Guides, Info & Tips on New Modern Linux Server Administration

Modern Server Administration of Critical Systems

This information pertains to very modern recent relases of Redhat based distributions, including the latest releases of CentOS and Fedora, which has had most of these service upgrades and replacements for the last few years now!



systemctl


The first such service upgrade actually replaced most, if not all of the service init.d startup & shutdown scripts with a very different way of managing the startup, status and shutdown of services, such as the Apache webserver, the CUPS print server, the secure shell, aka the SSH server, and all of the other services that used to be controlled by shell scripts located in the /etc/init.d/ directory. This directory still exists so that in the event that an old legacy service needs to still be managed by the init.d shell scripts, due to the service not yet having the required setup to be managed by the replacement of all of those scripts:



For instance, here is an example of systemctl being used to query the Secure Shell Server(SSH):

[root@fc24 ~]# systemctl status sshd.service
● sshd.service - OpenSSH server daemon
   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor pres
   Active: active (running) since Sun 2016-09-11 01:12:21 PDT; 1h 20min ago
     Docs: man:sshd(8)
           man:sshd_config(5)
  Process: 791 ExecStart=/usr/sbin/sshd $OPTIONS (code=exited, status=0/SUCCE
 Main PID: 810 (sshd)
    Tasks: 1 (limit: 512)
   CGroup: /system.slice/sshd.service
           └─810 /usr/sbin/sshd

Sep 11 01:12:20 fc24.dawgland.com systemd[1]: Starting OpenSSH server daemon.
Sep 11 01:12:21 fc24.dawgland.com systemd[1]: sshd.service: PID file /var/run
Sep 11 01:12:21 fc24.dawgland.com sshd[810]: Server listening on 0.0.0.0 port
Sep 11 01:12:21 fc24.dawgland.com systemd[1]: Started OpenSSH server daemon.
lines 1-15/15 (END)



This is what is looks like after stopping the SSH server:

[root@fc24 ~]# systemctl stop sshd.service
[root@fc24 ~]# systemctl status sshd.service
● sshd.service - OpenSSH server daemon
   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor pres
   Active: inactive (dead) since Sun 2016-09-11 02:38:55 PDT; 10s ago
     Docs: man:sshd(8)
           man:sshd_config(5)
  Process: 791 ExecStart=/usr/sbin/sshd $OPTIONS (code=exited, status=0/SUCCE
 Main PID: 810 (code=exited, status=0/SUCCESS)

Sep 11 01:12:20 fc24.dawgland.com systemd[1]: Starting OpenSSH server daemon.
Sep 11 01:12:21 fc24.dawgland.com systemd[1]: sshd.service: PID file /var/run
Sep 11 01:12:21 fc24.dawgland.com sshd[810]: Server listening on 0.0.0.0 port
Sep 11 01:12:21 fc24.dawgland.com systemd[1]: Started OpenSSH server daemon.
Sep 11 02:38:55 fc24.dawgland.com systemd[1]: Stopping OpenSSH server daemon.
Sep 11 02:38:55 fc24.dawgland.com systemd[1]: Stopped OpenSSH server daemon.
lines 1-14/14 (END)



And this is the command to start it back up, and because there is no output after starting it, I've also included the output of the status once again after starting the Secure Shell Server back up:

[root@fc24 ~]# systemctl start sshd.service
[root@fc24 ~]# systemctl status sshd.service
● sshd.service - OpenSSH server daemon
   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor pres
   Active: active (running) since Sun 2016-09-11 02:42:38 PDT; 9s ago
     Docs: man:sshd(8)
           man:sshd_config(5)
  Process: 2801 ExecStart=/usr/sbin/sshd $OPTIONS (code=exited, status=0/SUCC
 Main PID: 2803 (sshd)
    Tasks: 1 (limit: 512)
   CGroup: /system.slice/sshd.service
           └─2803 /usr/sbin/sshd

Sep 11 02:42:38 fc24.dawgland.com systemd[1]: Starting OpenSSH server daemon.
Sep 11 02:42:38 fc24.dawgland.com systemd[1]: sshd.service: PID file /var/run
Sep 11 02:42:38 fc24.dawgland.com sshd[2803]: Server listening on 0.0.0.0 por
Sep 11 02:42:38 fc24.dawgland.com systemd[1]: Started OpenSSH server daemon.
lines 1-15/15 (END)



dnf


Another BIG change to a "more modern" way of managing all of the software packages on your Linux machine, is the dnf command that is a direct drop-in replacement for yum, the old, tried and true RPM package manager that for going on 20 years has been the main interface to manage Linux software installations, taking into account all of the required dependencies, as well as uninstalling, more commonly referred to "removing" software packages.

Here is an example of how to use dnf to first search for, and then install over the internet, Blender, a very powerful tool to create your own custom animation, simulations and movies: 

[root@fc24 ~]# dnf search blender
Last metadata expiration check: 2:29:11 ago on Sun Sep 11 00:31:02 2016.
=========================== N/S Matched: blender ============================
blender.x86_64 : 3D modeling, animation, rendering and post-production



After searching for and finding the package I want to install, I then use dnf, NOT YUM!, to perform the dependency checking, downloading of the package along with the required dependencies, install all of the packages, and then perform what is called the "Cleanup" portion of the process.

This is how to use dnf to download, install, and then clean up any left over junk: 

[root@fc24 ~]# dnf install blender
Last metadata expiration check: 2:30:45 ago on Sun Sep 11 00:31:02 2016.
Dependencies resolved.
=============================================================================
 Package                      Arch      Version             Repository  Size
=============================================================================
Installing:
 Field3D                      x86_64    1.7.2-1.fc24        updates    519 k
 OpenColorIO                  x86_64    1.0.9-11.fc24       fedora     439 k
 OpenImageIO                  x86_64    1.6.16-1.fc24       updates    1.7 M
 blender                      x86_64    1:2.77a-1.fc24      updates     29 M
 boost-locale                 x86_64    1.60.0-7.fc24       updates    279 k
 boost-program-options        x86_64    1.60.0-7.fc24       updates    166 k
 boost-regex                  x86_64    1.60.0-7.fc24       updates    300 k
 fftw-libs-double             x86_64    3.3.4-7.fc24        fedora     805 k
 fonts-blender                noarch    1:2.77a-1.fc24      updates    4.7 M
 google-droid-sans-fonts      noarch    20120715-10.fc24    fedora     2.5 M
 hdf5                         x86_64    1.8.16-3.fc24       fedora     1.7 M
 jack-audio-connection-kit    x86_64    1.9.10-5.fc24       fedora     555 k
 jemalloc                     x86_64    4.2.1-1.fc24        updates    182 k
 libffado                     x86_64    2.2.1-8.fc24        fedora     690 k
 libspnav                     x86_64    0.2.3-3.fc24        fedora      17 k
 libxml++                     x86_64    2.40.1-2.fc24       fedora      89 k
 pugixml                      x86_64    1.7-2.fc24          fedora      92 k
 python3-numpy                x86_64    1:1.11.0-4.fc24     fedora     3.0 M
 tinyxml                      x86_64    2.6.2-11.fc24       fedora      54 k
 yaml-cpp03                   x86_64    0.3.0-9.fc24        fedora     151 k

Transaction Summary
=============================================================================
Install  20 Packages

Total download size: 47 M
Installed size: 178 M
Is this ok [y/N]: y



MariaDB


The long time "free" SQL server and client that used to be included in all standard Linux server installations server, MySQL, has been acquired by Oracle, and they've "commercialized" it, so that it is no longer "officially" free. This caused a bunch of long time developers to create what has become the "defacto" MySQL replacement, and uses the exact same MySQL commands that we have become accustomed to throughout the years.

This is how I installed MariaDB on my new Fedora Linux 24, the latest and greatest! In one command, I've installed both the server and client, along with all of their dependencies! Here's how I did it: 

[root@fc24 ~]# dnf install mariadb-server mariadb
Last metadata expiration check: 3:08:41 ago on Sun Sep 11 00:31:02 2016.
Dependencies resolved.

=================================================================

 Package                Arch        Version               Repository    Size

=================================================================

Installing:
 mariadb                x86_64      3:10.1.16-1.fc24      updates      6.3 M
 mariadb-common         x86_64      3:10.1.16-1.fc24      updates       66 k
 mariadb-config         x86_64      3:10.1.16-1.fc24      updates       29 k
 mariadb-errmsg         x86_64      3:10.1.16-1.fc24      updates      203 k
 mariadb-libs           x86_64      3:10.1.16-1.fc24      updates      654 k
 mariadb-server         x86_64      3:10.1.16-1.fc24      updates       19 M
 perl-DBD-MySQL         x86_64      4.036-1.fc24          updates      146 k
 perl-DBI               x86_64      1.634-3.fc24          fedora       729 k
 perl-Math-BigInt       noarch      1.9997.15-2.fc24      fedora       178 k
 perl-Math-Complex      noarch      1.59-362.fc24         updates       95 k
 perl-Storable          x86_64      1:2.53-348.fc24       updates       84 k

Transaction Summary

=================================================================

Install  11 Packages

Total download size: 28 M
Installed size: 140 M
Is this ok [y/N]:y
Retrieved from "https://thebestlinux.com/index.php?title=NewLinuxInfo&oldid=711"