How to know Linux OS versions Ubuntu/Centos/Redhat/

we can kow ubuntu versions with any one of following commands

lsb_release -aCopy

cat /etc/os-releaseCopy

hostnamectlCopy

we can kow Centos versions with any one of following commands

you need to execute below command how to know version with lsb based command

yum install redhat-lsbCopy

lsb_release -dCopy

Description: CentOS Linux release 7.4.1708 (Core)

lsb_release -rCopy

Release:7.4.1708

lsb_release -aCopy

hostnamectlCopy

/etc/centos-releaseCopy

/etc/os-releaseCopy

/etc/redhat-releaseCopy

/etc/system-releaseCopy