Monday, December 7, 2020

The Power Of A Dot In Linux Environment

Yes, there are several places where a dot (.) is being used in Linux terminal/Shell. In addition, a dot would depict some meaning when shown in the output of a command. Let us see the different places where we would normally use a dot and explore the other places where one could get to see this in Linux. The usage of a dot that is documented here is excluding the standard or regular use that is not specific to Linux/Unix and it is common across computer environments. Such as in representing a FQDN (Fully Qualified Domain Name) separated with dot, IP Address where each bit (from 0 to 255) is separated by a dot etc, 

Monday, October 12, 2020

Some Differences Between Red Hat Satellite & SUSE Manager

Red Hat SatelliteSUSE Manager
Upstream VersionIn Red Hat Satellite (version 6 on-wards) there are multiple open-source upstream projects involved such as Foreman, Katello, Pulp, Candlepin etc,. In earlier version which is Satellite version 5, spacewalk was being used.Uyuni (a fork of Spacewalk, based on SaltStack) is the upstream for SUSE Manager 4 and later releases. "Spacewalk" was used earlier.
Current Version*Red Hat Satellite 6.7SUSE Manager 4.1

Friday, July 3, 2020

Top 10 Dangerous Operations or Commands To Be Executed Carefully In Linux

I’ve come up with these 10 categories of tasks/commands/operations which would render a system un-usable or may cause service disruption or network outage when executed without proper precaution or understanding of the impact of the command and how it works. Most of these commands would also have a forceful execution option which doesn’t even raise a prompt before execution(when run by root or any privileged sudo user). This is in addition to the notorious recursive & forceful file removal command (rm -rf /). I’ve not considered the standard shutdown/reboot commands since these are known and understood by the command itself. Some of the commands would certainly require a root privilege, but the point here is that even as a root user, such commands should never be executed without understanding the details.

Monday, May 4, 2020

Lets Upgrade From RHEL7 To RHEL8

It has been quite some time since RHEL8 was released. Red Hat has officially announced the upgrade support from RHEL6 → RHEL7 & RHEL7 → RHEL8. This is with certain conditions and limitations. One has to read the complete document from Red Hat to understand the caveats about it. As per the official documentation from Red Hat, only Server variant is supported. So, let’s first understand certain important limitations before we could plan the upgrade. 

Monday, March 16, 2020

How to completely disable boot or startup messages?

Yes, there are situations where we’d get to see such requirements. So, a system should not show any boot or kernel or any messages whatsoever when booting and it should simply trigger/show the final GUI or CLI login screen. That is right. Sometimes it would be required to create such a system. In most recent versions of systemd based systems this could be achieved by nullifying systemd boot logs along with other options. Lets see how to get this done.

Saturday, January 18, 2020

How-To Safely Remove A Storage Device From A Linux System?

There are situations where we would be required to remove a storage device or LUN from a system and attach it to another system for some other important purpose. So, how could this be achieved? Yes, we could remove a storage device attached to a system safely provided the system has enough bandwidth to accommodate data on another available volume. In this blog page, I’ve tried to document all the steps with screen-shots to demonstrate the same procedure. I hope this helps someone and if so, please leave a comment or hit Like button. Thank you!