Check the CentOS/RHEL OS Update Level

check-os-release.txt

# Source: https://www.thegeekdiary.com/how-to-check-centos-version/
# package centos-release
  rpm -ql centos-release | grep release$

    cat /etc/redhat-release
    cat /etc/centos-release
    cat /etc/os-release
    cat /etc/system-release

    rpm -qf /etc/redhat-release


# Check the Running Kernel version
  uname -s -r

  uname -a

  #Check kernel compile time (uname -v) and compare with known value:
    uname -v
  
  # You can also Verify the kernel package using the rpm command. The command would produce an output only if there is any issue with the installed kernel.
  rpm -q --verify kernel-3.10.0-693.21.1.el7.x86_64
  
  # Checking CentOS 7 version
    hostnamectl
  
		# Checking the LSB version
			Another way to check the centOS version is using the “lsb_release” command. The lsb_release command is provided by the package “redhat-lsb”. This package may not be present by default on the system and you may need to install it first.
			
				yum install redhat-lsb
				
				lsb_release -d
				
				lsb_release -r
				
				lsb_release -a
				
	# Check OS version with GRUB configuration files
		Using the GRUB configuration file is not a recommended way of checking the OS version, but I would still like to mention this method here for your information. Search for the “menuentry” (For CentOS 7) and “title” (For CentOS 6) in the GRUB configuration file to find the OS version.
		
		# CentOS 7 Example
			cat /boot/grub2/grub.cfg | grep -w menuentry
			
			# In case of CentOS 7, you can also get the current kerel version from the file /boot/grub2/grubenv. For example:
				grep saved_entry /boot/grub2/grubenv
				
		# CentOS 6 Example
			cat /boot/grub/grub.conf | grep title