How to find out the previous kernel version on CentOS after a reboot

To find out the previous kernel version on CentOS after a reboot, you can use the rpm command to query the package database. Here are the steps:

Open a terminal or SSH session to your CentOS server.

Type the following command to list all installed kernels:

rpm -qa | grep "kernel-[0-9]"

This will output a list of all installed kernel packages.… Read the rest

How to install atop

Enable epel repository if needed

## RHEL/CentOS 7 64-Bit ##
wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh epel-release-latest-7.noarch.rpm
yum install atop -y

Useful URLs:

https://www.tecmint.com/how-to-enable-epel-repository-for-rhel-centos-6-5/

https://www.tecmint.com/how-to-install-atop-to-monitor-logging-activity-of-linux-system-processes/Read the rest