1) 登录到服务器执行 lsb_release -a ，即可列出所有版本信息，例如：

[root@3.5.5Biz-46 ~]# lsb_release -a
LSB Version: 1.3
Distributor ID: RedHatEnterpriseAS
Description: Red Hat Enterprise Linux AS release 4 (Nahant Update 1)
Release: 4
Codename: NahantUpdate1
[root@3.5.5Biz-46 ~]#

这个命令适用于所有的linux，包括Redhat、SuSE、Debian等发行版。

2) 登录到linux执行cat /etc/redhat-release ，例如如下：
[root@3.5.5Biz-46 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux AS release 4 (Nahant Update 1)
[root@3.5.5Biz-46 ~]#

这种方式下可以直接看到具体的版本号，比如 AS4 Update 1

3）登录到linux执行rpm -q redhat-release ，例如如下

[root@3.5.5Biz-46 ~]# rpm -q redhat-release
redhat-release-4AS-2.4
[root@3.5.5Biz-46 ~]#

这种方式下可看到一个所谓的release号，比如上边的例子是2.4
这个release号和实际的版本之间存在一定的对应关系，如下：

redhat-release-3AS-1 -> Redhat Enterprise Linux AS 3
redhat-release-3AS-7.4 -> Redhat Enterprise Linux AS 3 Update 4
redhat-release-4AS-2 -> Redhat Enterprise Linux AS 4
redhat-release-4AS-2.4 -> Redhat Enterprise Linux AS 4 Update 1
redhat-release-4AS-3 -> Redhat Enterprise Linux AS 4 Update 2
redhat-release-4AS-4.1 -> Redhat Enterprise Linux AS 4 Update 3
redhat-release-4AS-5.5 -> Redhat Enterprise Linux AS 4 Update 4

注意：第（2）（3）两种方法只对Redhat Linux有效