Content

2018

August

How to configure and Install kdump (crashkernel) in RHEL/CentOS 7
How to fix “NoValidHost: No valid host was found. There are not enough hosts available” during overcloud deployment (openstack)
Final Part 3: Openstack TripleO Architecture and Step By Step Guide for installation of undercloud and overcloud nodes (compute, controller, ceph-storage)
Part 2: Openstack TripleO Architecture and Step By Step Guide for installation of undercloud and overcloud nodes (compute, controller, ceph-storage)
Part 1: Openstack TripleO Architecture and Step By Step Guide for installation of undercloud and overcloud nodes (compute, controller, ceph-storage)
How to check memory usage of an individual process or application/program in Linux
How to enable or disable transparent (THP) and explicit (nr_hugepages) hugepage and check the status in Linux with examples (explained in detail)
What is transparent hugepage (THP) and how to check THP usage per process in Linux (Explained)
How to lock or unlock a root and normal user account using pam_tally2 and pam_faillock after certain number of failed login attempts in Linux

July

How to check the swap memory usage by a process in Linux
How to test ssh connection using bash script in Linux
Part 4: How to create, launch and connect to an instance from scratch in Openstack
Part 3: Create Glance Image, Cinder Volumes, Flavor Templates and key pairs for an Instance in Openstack
Part 2: Configure Openstack OVSBridge, Network (Neutron), Public and Private Network, Router in Openstack
Part 1: Step by Step Guide to Install Openstack using Packstack with Compute and Controller node on RHEL 7

June

How to check and compare rpm version and release in Linux using bash script
How to configure local customised repository for zypper based installation in SuSE Enterprise Linux
How to measure power consumption in watts using powerstat in Linux with examples
How to set or edit quota limit for a user or file-system, assign or modify grace period with examples in Linux
What are the CPU c-states? How to check and monitor the CPU c-state usage in Linux per CPU and core?

May

How to send log messages using rsyslog to remote server using tcp and udp ports (remote logging) in Red Hat Linux
How to check the HBA name, make, model, firmware, driver version in Linux
How to check the number of HBA cards or ports are available in my Linux setup ?
Tutorial/Cheatsheet: Begineer’s Guide to Understanding Device Mapper Multipath for Linux
How to execute a script at %pre, %post, %preun or %postun stage (spec file) while installing/upgrading an rpm
How to sign a key using gpg key (password or password-less) to an rpm in Linux
How to change rpmbuild (_tmppath) in a spec file (rpmbuild ignored directory) Linux
How to build a signed rpm from scratch by building a source archive using Red Hat Linux
How to view and increase the default pipe buffer size in Linux (F_GETPIPE_SZ, F_SETPIPE_SZ)
How to reduce and/or add more columns or fields to top command in Linux (swap, memory, etc)
How to disable or restrict direct root login via console or ssh
How to clear/delete all the partition table from a disk or partition in Linux

April

March

Best practices to harden and increase security with ssh (ciphers, MACs etc)
Step by Step Guide to Install and configure VCSA 6.5 with Embedded Platform Service Controller
How to reset iLO4 password remotely using Onboard Administrator
Step by step tutorial guide with screenshots to Install and Configure VMware ESXi 6.5

February

How to make bootable Pendrive (USB) to install Windows, Linux, VMware from an ISO
How to set date and time in iLO3 / iLO4 using SNTP and RIBCL scripts from Onboard Administrator in HP Proliant Blades
HP iLO4 command line interface (CLI) guide and cheatsheet with examples
How to configure Shared Uplink Set Network in HP Flex Virtual Connect using CLI commands with example (cheatsheet)
How to configure NTP client to sync with NTP server during system startup (boot) in (RHEL 7 / CentOS 7) Linux
Step by Step Guide to create autoyast xml file for SuSE Linux (SLES) with examples
what is the difference between sub-query and co-related sub-query?
How to change or customise login prompt for ksh shell in Linux (with examples)
Step by Step tutorial guide to configure BIND DNS server in chroot environment for Red Hat (RHEL/CentOS) 7
How to customize and change color of the bash login prompt in Linux
10 examples to customize or change the login prompt using PS1 variable of bash shell in Linux

January

How to check and update planned day light saving (DST) changes (timezone) in Linux
How to assign a service to a specific core using systemd in RHEL 7 / CentOS 7
How to disable or enable hyper threading on my Linux server
How to limit CPU count or disable CPUs in a multi core server in RHEL 7 / CentOS 7
How to check if Hyper Threading (HT) is enabled or disabled on my Linux server
How to clean temporary files automatically using systemd-tmpfiles in RHEL 7 / CentOS 7
How to create a user (normal and root) using kickstart configuration file in RHEL 7 / CentOS 7
How to create a sequence which start with 1 and next value will be 0 and then next value is 1 and then 0 .. and so on … is this possible ?
How to boot RHEL 7 / CentOS 7 to single user runlevel or rescue mode (emergency.target) ?
Tutorial / Cheatsheet:12 practical examples for different sudo access based scenarios in RHEL 7 / CentOS 7
Tutorial/Cheatsheet: 11 examples to use systemctl to manage unit files and service in RHEL 7/CentOS 7

Understanding syntax, arguments, aliases used in sudoers file with examples (visudo)

2017

December

Step by Step Linux boot process with GRUB2 and systemd in RHEL 7 / CentOS 7
How do I set or change (default) runlevel using systemd in CentOS 7/RHEL 7
Host gets stuck at certain percentage while entering maintenance mode in Full Data Migration (VMware, vSAN)
How to use iperf3 tool to monitor network bandwidth in Linux
sed: add or append character at beginning or end of line (row) of a file
sed: Ignore whitespace while matching a pattern
How to fix “Postponed keyboard-interactive for invalid user <username> from <host> port <port_no> ssh2 [preauth]”
How to print or grep only the matched string or text or word or pattern in Linux using bash
How to forcefully sync date and time using the NTP server in Linux
How to redirect specific log messages to separate log file using rsyslog in Linux
How to find ethernet network card firmware and driver information in Linux

November

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July

June

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April

2016

September

April

2014

October

September

How to do a case sensitive search inside vi editor in Linux
How does a successful or failed login process works in Linux
How to find all the process accessing a file in Linux
How to exclude multiple directories from du command in Linux
How to configure autofs in Linux and what are its advantages?
How to resize software raid partition in Linux
Step by step guide to configure software raid 1 (mdadm)
How to prevent a command from getting stored in history in Linux

June

Comparison and Difference between vSphere 5.1 and 5.5
How to run any script or cron job in Linux for every second
Linux General and Permission (QUIZ)
Oracle Database (QUIZ)
Linux User and Accounts Management (QUIZ)
Installing Linux and Linux Kernel (QUIZ)
How to keep a track of all the commands run by any user in Linux
How do you check Linux machine is Physical or Virtual remotely?
df shows 100% full partition even when there is space on the disk
How to configure passwordless sudo for a user in Linux
Understanding Load Average in Linux and when to be worried about it?
How to run a process in background or bring to foreground in Linux
How to configure logrotate for a new log file in Red Hat Linux
How to secure boot loader (grub menu) with password in RHEL 6
Disk Attachment Technology FC vs SAS vs iSCSI

May

April

Overview of services used in Red Hat Cluster
How to find/view all the members of a group in Linux
10 practical examples to use USERADD command in linux
What is the difference/comparison between Unix and Linux ?
How to fix “E575: viminfo: Illegal starting char in line”
What are the maximum and minimum limits for RHEL 4 vs 5 vs 6 ?
RAID levels 0, 1, 2, 3, 4, 5, 6, 0+1, 1+0 features explained in detail
VMware Workstation throws internal error when powering on VM
10 Practical Examples for using FIND Command in Linux

March

How to rename Logical Volume and Volume Group in Linux
Step by Step Linux Boot Process Explained In Detail
How to remove logical and physical volume from Volume Group in Linux
What is the difference between ext3 and ext4 filesystem in Linux ?
How to change default login shell permanently in linux
How to install libraries manually in Linux
How to extend/resize Logical Volume and Volume Group in Linux
How to generate ER diagram using Oracle SQL developer
What is GRUB Boot Loader ?
How to configure BIND-9.8 DNS server in Red Hat Linux 6
Existing lock /var/run/yum.pid: another copy is running
How to configure a caching only bind DNS server in Red Hat Linux
Iptables rules to allow/block ssh incoming/outgoing connection in Linux
Iptables rules to block/allow icmp ping request in Linux
How to configure Private Network in VMware Workstation
10 examples to help you understand top command usage in Unix/Linux
Script to take backup of any critical directory in Unix/Linux

February

Configure Red Hat Cluster using VMware, Quorum Disk, GFS2, Openfiler
Tutorial for Monitoring Tools SAR and KSAR with examples in Linux
How to configure Samba 4 Secondary Domain Controller
RHEL: Kernel will not boot, system freeze at ‘starting udev’
How to secure Apache web server in Linux using password (.htaccess)
How to register Red Hat Linux with RHN (Red Hat Network )
Red hat Enterprise Linux 5.5 Installation Guide (Screenshots)
15 tips to enhance security of your Linux machine
Why is Linux considered more safer than windows or any other OS ?
What is the difference between “su” and “su -” in Linux?
What is kernel-PAE in Linux?
What is swappiness and how do we change its value?
How to log iptables messages in different log file
What are the s and k scripts in the etc rcx.d directories
How to check all the currently running services in Linux
How to auto start service after reboot in Linux
What is virtual memory, paging and swap space?

January

Interview Questions on Linux Servers with Answers
What is the difference between DNS A record and CNAME record?
Tutorial for SYSLOG with Examples in Red Hat Linux
General Linux Interview Questions with Answers
Interview Questions on Linux Permissions with Answers
Interview Questions on Linux Networking
Interview Questions on Linux User management with Answers
Interview Questions on Linux Filesystems with Answers
What is a Kernel in Linux?
How does a DNS query works when you type a URL on your browser?
How to create password less ssh connection for multiple non-root users
How to create user without useradd command in Linux
How to unlink/delete a symbolic in Linux
How to give normal user root privileges using sudo in Linux/Unix
How to do Ethernet/NIC bonding/teaming in Red Hat Linux
How to install/uninstall/upgrade rpm package with/without dependencies

June

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February

January

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December

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August