1、cat /etc/issue，此命令也适用于所有的Linux发行版。
[root@S-CentOS home]# cat /etc/issue
CentOS release 6.5 (Final)
Kernel \r on an \m

2、cat /etc/redhat-release，这种方法只适合Redhat系的Linux：
[root@S-CentOS home]# cat /etc/redhat-release
CentOS release 6.5 (Final)

3、lsb_release -a，即可列出所有版本信息：
[root@S-CentOS ~]# lsb_release -a
LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: CentOS

4、hostnamectl，即可列出本机版本信息（推荐）：
[root@vm37925 ~]# hostnamectl
Static hostname: vm37925
Pretty hostname: VM37925
Icon name: computer-vm
Chassis: vm
Machine ID: 5d969bf4a9488142faf59ba
Boot ID: cc0274ffaa9ba97d6c440
Virtualization: kvm
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 5.13.5-1.el7.elrepo.x86_64
Architecture: x86-64