从头开始积累centos7系统运用
大牛博客：https://blog.51cto.com/yangrong/p5
1.关闭selinux功能：
SELinux(Securety-EnhancedLinux)是美国国家安全局（NSA）对于强制访问控制的实现，这个功能让系统管理员又爱又恨，
这里我们还是把它给关闭了吧，至于安全问题，后面通过其他手段来解决，这也是大多数生产环境的做法，如果非要开启也是可以的，
关闭方式如下：enforcing改成disabled
加 -i才是修改，不加只是查看。修改配置文件
sed 's#SELINUX=disabled#SELINUX=enforcing#g' /etc/selinux/config
路径：
[root@python01 ~]# cat /etc/selinux/config
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three values:
# targeted - Targeted processes are protected,
# minimum - Modification of targeted policy. Only selected processes are protected.
# mls - Multi Level Security protection.
SELINUXTYPE=targeted
[root@python01 ~]# grep 'SELINUX=disabled' /etc/selinux/config
SELINUX=disabled
[root@python01 ~]# grep 'disabled' /etc/selinux/config
# disabled - No SELinux policy is loaded.
SELINUX=disabled
以上修改配置文件后selinux还是没有生效：
查看selinux状态：
[root@python01 ~]# getenforce
Disabled
[root@python01 ~]# setenforce
usage: setenforce [ Enforcing | Permissive | 1 | 0 ]
仅仅开启警告：重启后生效
[root@python01 ~]# setenforce 0
2.运行级别：
[root@python01 ~]# cat /etc/inittab
# inittab is no longer used when using systemd.
#
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
#
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
#
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
#
# To view current default target, run:
# systemctl get-default
#
# To set a default target, run:
# systemctl set-default TARGET.target
#
[root@python01 ~]# runlevel
N 5
[root@python01 ~]# systemctl get-default
graphical.target
3.关闭防火墙：
查看防火墙状态：systemctl status firewalld.service
关闭：systemctl stop firewalld
开启：systemctl start firewalld
开机自动关闭：systemctl disable firewalld
开机自动启动：systemctl enable firewalld
4.中文乱码：
[root@python01 ~]# cat /etc/locale.conf
#LANG="zh_CN.UTF-8"
LANG="en_US.UTF-8"
5.setup命令工具：没试过
yum install setuptool
yum install ntsysv
yum install iptables
yum install system-config-securitylevel-tui
yum install system-config-network-tui
6.见19 history命令
7.特殊变量设置：不用做到系统里面，知道就好了
[root@python01 ~]# echo 'export TOUT=300' >>/etc/profile
[root@python01 ~]# echo 'export HISTSIZE=5' >>/etc/profile
[root@python01 ~]# echo 'export HISTFILESIZE=5' >>/etc/profile
8.隐藏linux系统信息
清空以下文件内容即可
[root@python01 ~]# cat /etc/issue
S
Kernel
on an m
[root@python01 ~]# cat /etc/issue.net
S
Kernel
on an m
9.快照的概念：
可以还原系统到指定快照时间
10.克隆虚拟机：学习专用
以一台机为标准（快照）：