System Administration Guides and Best Practices

How to grep multiple strings and patterns in single line from a file in Linux or Unix? Is it possible to grep multiple strings using single command from a file?

Step by step Guide to install Oracle Virtual Box on RHEL / CentOS 7 Linux. To install Oracle Virtual Box you need EPEL repo. Oracle Virtual 5.2 is out now

Steps to enable SSH access in linux rescue mode and configure network in rescue mode in RHEL/CentOS 7/8 with example transfer sosreport file inst.sshd=1

What is .swp file? Why this file is created? How to get rid of Found a swap file by the name warning? Another program may be editing the same file. An edit session for this file crashed

How to disconnect idle ssh session in Linux using ClientAliveInterval and ClientAliveCountMax. SSH close connection after sometime. How to close ssh connection

Steps to disconnect hung ssh session. Kill ssh session. Terminate stuck ssh session. Kill unresponsive ssh session. Disconnect pssh session in Linux

C++ provides several file I/O functions that enable programmers to write and read data from files. One of these functions is WriteFile, which is part of the

To find or get complete dependencies list of rpm you can use rpm, yum and repoquery command for both installed and non installed package

Tutorial guide to install systemtap (stap) to extract, filter and summarize data to enable diagnosis of complex performance. Systemtap Tutorial Linux

How to set default boot kernel in linux? Change the default boot entry for kernel ? Boot with old kernel version ? Revert to previous kernel version ?

How to delete iscsi target? Remove inactive iscsi target? Remove iscsi storage target from initiator? Remove iscsi virtual disk on CentOS / RHEL 7 Linux.

How to backup or copy and restore partition table in linux. linux clone partition table, linux repair partition table

Prevent brute force SSH attacks in RHEL CentOS 7 with examples using Fail2ban, account lockout, SSH rate limit using iptables, sshd_config, SHA512 hashing

In c++ cin array is not performed in one cin statement. In this article we will learn about array input in c++. To understand array input, we first need to

Steps to set default boot kernel in RHEL 8 using grubby and boot with old kernel version. Check the kernel version which will get activated after reboot

Configure SSH Host Based Authentication using sshd_config, shosts,equiv per user RHEL/CentOS 7/8. Compare Host based authentication vs public key authentication

How to allow SSH for root login only from specific host or IP address? How to configure and restrict SSH to permit login only for certain users and/or groups?

Steps to convert image format, resize image percentage, scale using imagemagick in linux. shell script to batch resize image and convert image format in linux.

Set and Modify kernel command line arguments, update GRUB2 in RHEL 8 using grub2-editenv, grubby and grub2-mkconfig with examples to disabled IPv6 RHEL 8 Linux

Step by step tutorial to join or add CentOS 8 to Windows Domain Controller running on Windows Domain Controller Active Directory on 2012 R2 using winbind RHEL 8

linux single user mode, centos 7 single user mode, rhel 7 single user mode, single user mode linux, how to boot into single user mode linux, centos single user mode, single user mode

Step by Step instructions to install iredmail on rocky linux 8 with screenshots. Install and Configure iredmail server GUI

Add timestamp to SSHD DEBUG logs using while loop. Prepend timestamp to STDOUT and log file for DEBUG logs

Examples and commands to show NFS shares on NFS server, List NFS mount points on NFS Clients, List NFS clients connected to the NFS server, List NFS shares in Linux

This tutorial contains a list of nfs exports options in Linux with examples to create NFS share using /etc/exports. You can share with multiple hosts, single or world

Fix kickstart clearpart not working error in RHEl/CentOS 7/8 Linux, kickstart fails to delete existing partitions using zerombr and clearpart in Linux

How can I restrict my postfix smtp relay server to be used by only certain IP Address, How to block or allow postfix relay access using mynetworks example

How to reject mail for unknown users on localhost with Postfix with local_recipient_maps with example

Step by step guide to disable and blacklist kernel module using GRUB2 and modprobe.d in Red Hat and CentOS 7 and 8 Linux. Permanently unload kernel module