While researching an old install for an upgrade system
requirement compliance, I discovered that I b=need to validate which Linux
version was installed. So, here is a
quick note on the command I used to validate which version of Linux was
The new CentOS 8 rebuild
is out. Christened version 8.0-1905, this release provides a secure, stable and
a more reliable foundation for CentOS users such as organizations running
high-performance websites and businesses with Linus experts that use CentOS
daily for their workloads, but who do not need strong commercial support.
The new OS comes in
after Red Hat released RHEL 8 – Red Hat Enterprise Linux – in May of this year.
According to CentOS 8 release notes, the contributors note that this rebuild is
100% compliant with Red Hat’s redistribution policy. This Linux distro allows
users to achieve successful operations using the robust power of an
enterprise-class OS, but without the cost of support and certification. Below
are some of the updates as outlined in CentOS 8 release notes that you can
expect with this new release and some of the deprecated features.
What’s New in the Just Released CentOS 8?
BaseOS and Appstream
New container tools
TCP stack improvements
· BaseOS and Appstream
The main repository or
Base Operating System offers the components of distribution that in turn
provide the running user space on the hardware, virtual machines, or even a
container. The Application Stream or App stream offers all the apps you might
want to run in particular user space. The Supplemental repository offers
software that comes with special licensing.
· New Container Tools
With the aid of Podman,
CentOS 8 supports Linux Containers. This replaces Docker and Mobdy, which
depend on daemon and run as root. Unlike the previous release, the Podman in
the new version does not depend on daemon. Podman allows users to create images
from scratch using Buildah.
· Systemwide Crypto Policies
The command “update
crypto policies” can be used to update the system-wide cryptographic policy on
the new OS. The policies have settings for the following applications and
libraries; NSS TLS library, Kerberos 5 library, Open SSH SSH2 protocol
implementation, IKE protocol implementation & Libreswan IPsec, Open SSL TLS
library and GnuTLS
· TCP Stack Improvements
The CentOS 8 Linux
distro also brings with it TCP stack version 4.16 with an improved ingress
connection rate. The Linux kernel is now able to support the new BBR and NV
control algorithms. This is very helpful in helping improve the Linux server
· DNF – Dandified Yum
The new Operating System
includes the basic foundations of the Yum package but is now upgraded to the
DNF (Dandified Yum). Though it maintains a similar command-line interface and
API to its predecessor, it does promise to be faster, seamless and
The CentOS also has a
compiler based on the version 8.2 and includes support for more recent C ++
language standard versions, improved optimizations, more code, and hardening
techniques as well as new hardware support and better warnings.
In addition to those
features, the new CentOS 8 also supports secure guests, which using
cryptographically signed images will ensure that the program retains its
integrity. It also boasts of improved management of memory and support. CentOS
8 release notes state that the new OS will allow the Crash dump to take in
kernel crash during all booting phases which were not possible before.
CentOS 8 gives encrypted
storage to LUKS2. It also allows for enhancements made to the process scheduler
to include the new deadline process scheduler. This Linux distro will also
enable installations and boot from dual-in-line, non-volatile memory modules.
A great bonus feature is
that you can manage the new software with Cockpit via a web browser. This
feature is very user-friendly, making it great for system administrators and
new users alike.
If you are upgrading
from previous CentOS versions, the most significant change is seen in the
nftables framework which has replaced iptables. Nfatables allows users to
perform network address translation (NAT) mangling, packet classification, and
packet filtering. Unlike iptables, nfatables helps to provide secure firewall
support with enhanced performance, increased scalability, and easy code
These changes, though
not major, may cause problems with firewall functionality. Although upgrades
using RHEL may be supported, it is not advisable to upgrade directly from much
older versions of CentOS like CentOs 6 and below as they may not be compatible.
Users of CentOS as a
desktop will see an update of the GNOME SHELL default interface to version
3.28, while still carrying the default display server as Wayland.
If you are looking to
upgrade from previous versions, a system to do so directly is yet to be
released. As such, your most favorable option would be to back up your data as
you install the newly released CentOS 8. When it is up and running, you can
then move all the data to the new system.
Nonetheless, the new
CentOS 8 Linux release is an exciting feat. This OS provides a manageable and
consistent platform that suits a wide variety of deployments. It comes with
well-thought-out and ingenious software updates that will help avid users to
build more robust container workloads and web apps.
Despite the ‘man’ commands, relative simplicity and
appearance of unimportance, the ‘man’ command is, perhaps, one of the most
important commands to lean in Linux.
the ‘man’ command important?
The true value of the ‘man’ command is that provides access
to the online manuals (documentation), which will be consulted often until
Linux commands and functions have to be learned and internalized. Even after learning the more familiar and
commonly used Linux command and functions, one will still need to refer the
less commonly used capabilities or to confirm something which has been used in
When some the more arrogant Linux users will sometime tell
folks with questions to “read the frickin’ manual” (RTFM), the ‘man’
command is what they are usually talking about.
Although there are other perfectly useful reference materials online
(e.g., git documentation project) or commercial books, the ‘man’ command should
be the go-to place for documentation.
The reason this is actually very simple, if the command or function is
installed in your version or environment instance of Linux, then man pages will
be available. Therefore, usually, there
will no need to go search on the internet for answers or carrying books around.
The syntax of the ‘man’ command is simple and easy to learn
to use. In fact, the ‘man’ command is so
easy to use that people frequently will not even use options when they use the
man command and enter ‘man’ command and the keyword.
‘man’ command syntax
man [options] (keywords)
Simple examples to illustrate how to use the ‘man’ command.
Example to pull up the
‘Man’ command documentation
[blog-server ~]$ man man
In this example, the man command is using ‘man man’ to pull up its own online
Example to pull up the
‘ls’ command documentation
[blog-server ~]$ man ls
In this example, the man command is using ‘man ls’ to pull up the ‘list directory
contents‘ online documentation.
list directory contents
Example to pull up
the ‘cp’ command documentation
[blog-server ~]$ man cp
In this example, the man command is using ‘man cp’ to pull up the ‘copy files and
directories ‘ online documentation.
Example screenshot of
the ‘cp’ (copy files and directories) file command online documentation
The Linux move command (mv) is one of the essential commands,
which can be very useful in Linux, Unix, and AIX. The primary purpose of the move command is
obviously to move files, and of course, directories. The move command may also be used to rename
files and to make backups.
$ mv [options] source (file or directory) destination
Move Command options
force move by overwriting destination file
interactive prompt before overwriting
update – move when the source is newer than the
verbose – print source and destination files
MV – t
explicitly saying to move the file or directory here,
rather trying to fit everything into the last argument.
Move all (Multiple) files to a specific director without
listing by name
For More move command
details see the Linux documentation manuals using the man command
$ man mv
Here are some quick and very simple move command (MV)
examples for reference.
Move Move to
files to the /Archive/ directory:
$ mv happy.txt garden.txt /Archive/
Move all “.txt” files
in the current directory to subdirectory backup:
$ mv *.txt backup
Move all files in
subdirectory ‘backup’ to current directory:
$ mv backup/*
Rename file happy.txt
to happy.bak filename:
$ mv happy.txt happy.bak
Rename directory backup
$ mv backup backup2
Update – move when happy.txt
is newer or missing in target directory:
$ mv -u happy.txt backup
Move happy.txt and
prompt before overwrite backup / happy.txt: