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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 installed.
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.
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.
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.
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 TLS library.
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 internet speed.
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 super-efficient.
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 maintenance.
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 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 a while.
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 [options] (keywords)
Simple examples to illustrate how to use the ‘man’ command.
[blog-server ~]$ man man
In this example, the man command is using ‘man man’ to pull up its own online 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
[blog-server ~]$ man cp
In this example, the man command is using ‘man cp’ to pull up the ‘copy files and directories ‘ online documentation.
To install the locate command (mlocate) in Redhat or Centos, use the ’YUM’ command, install function.
[root@blog-server ~]# man locate
[root@blog-server ~]# yum install mlocate
[root@blog-server ~]# sudo yum install mlocate
Then run the [root@data-server ~]# updated
[root@blog-server ~]# updated
[root@blog-server ~]# sudo updatedb
To quit the Linux ’vi’ editor without saving any changes which have been made:
: q!
This will quit the Linux VI editor, and all changes the document made in this session will be lost.
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
| option | description |
| mv -f | force move by overwriting destination file without prompt |
| mv -i | interactive prompt before overwriting |
| mv -u | update – move when the source is newer than the destination |
| mv -v | 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. |
| mv * | Move all (Multiple) files to a specific director without listing by name |
$ man mv
Here are some quick and very simple move command (MV) examples for reference.
$ mv happy.txt garden.txt /Archive/
$ mv *.txt backup
$ mv backup/*
$ mv happy.txt happy.bak
$ mv backup backup2
$ mv -u happy.txt backup
$ mv -v happy.txt backup
The “Set Number” command in the VI (visual instrument) text editor seems may not seem like the most useful command. However, it is more useful than it appears. Using the “set number” command is a visual aid, which facilitates navigation within the VI editor.
The “set Number” command is used to make display line numbers, to enable line numbers:
A column of sequential line numbers will then appear at the left side of the screen. Each line number references the text located directly to the right. Now you will know exactly which line is where and be able to enter a colon and the line number you want to move to and move around the document lines with certainty.
When you are ready to turn offline numbering, again follow the preceding instructions, except this time, enter the following line at the : prompt:
Normally, vi will forget the setting you’ve chosen once you’ve left the editor. You can, however, make the “set Number” command take effect automatically whenever you use vi on a user/account, enter the “set Number” command as a line in the .exrc file in your home directory.
