[root@centos68 ~]# more /etc/issue
CentOS release 6.9 (Final)

[root@centos68 ~]# cat /etc/redhat-release
CentOS release 6.9 (Final)

[root@centos68 ~]# uname -a
Linux centos68 -.el6.x86_64 # SMP Tue Apr  :: UTC  x86_64 x86_64 x86_64 GNU/Linux

[root@centos68 ~]# cat /proc/version
Linux version -.el6.x86_64 (mockbuild@c1bm.rdu2.centos.org) (  (Red Hat -) (GCC) ) # SMP Tue Apr  :: UTC 

／proc文件系统，它不是普通的文件系统，而是系统内核的映像，也就是说，该目录中的文件是存放在系统内存之中的，
它以文件系统的方式为访问系统内核数据的操作提供接口。而我们使用命令“uname -a”的信息就是从该文件获取的。

[root@centos68 ~]# getconf LONG_BIT

[root@centos68 ~]# cat /etc/passwd|grep -v nologin|grep -v halt|grep -v shutdown|awk -F":" '{ print $1"|"$3"|"$4 }'|more
root||
|
wenqiang||

[root@centos68 ~]# file /bin/bash
/bin/bash: ELF -bit LSB executable, x86-, version  (SYSV), dynamically linked (uses shared libs), , stripped

getconf -a