linux优化——永久关闭SELinux和iptables，修改字符集，命令行参数补齐

永久关闭SELinux

[root@centos ~]# vi /etc/selinux/config   #将enforcing改为disabled
# 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 these two values:
#     targeted - Targeted processes are protected,
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted
                                                                                   
"/etc/selinux/config" 13L, 457C written
[root@centos ~]# setenforce
usage:  setenforce [ Enforcing | Permissive | 1 | 0 ]
[root@centos ~]# setenforce 0
[root@centos ~]# getenforce
Permissive

永久关闭iptables

对于iptables关闭或开启建议

1）服务器可以被外界访问（公网/外网ip），iptables开启

2）内部环境（局域网/没网ip）iptables关闭

3）高并发的iptables关闭

 

a) 临时关闭iptables

通过脚本关闭： /etc/init.d/iptables  stop

通过服务关闭： service iptables stop

查看当前iptables的状态：/etc/init.d/iptables status

 脚本和服务关闭等价，但脚本关闭支持tab补全，建议使用脚本关闭。

b) 永久关闭iptables

注：管理开机自启动服务（软件）-chkconfig

查看iptbales是否开机自启动：chkconfig |grep iptable或者chkconfig --list|grep iptables，两者等价

关闭iptbales：chkconfig iptables off，更精细的关闭是chkconfig --level 3 iptables  off

[root@centos ~]# /etc/init.d/iptables  stop
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]
[root@centos ~]# service iptables stop
[root@centos ~]# /etc/init.d/iptables status
iptables: Firewall is not running.
[root@centos ~]# chkconfig --list|grep iptables
iptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off
[root@centos ~]# chkconfig |grep iptables
iptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off
[root@centos ~]# chkconfig --level 3 iptables off
[root@centos ~]# chkconfig |grep iptables

iptables        0:off   1:off   2:on    3:off   4:on    5:on    6:off

修改字符集

字符集显示不正常可能是客户端（xshell/secureCRT/putty）或虚拟机端字符集设置问题。针对虚拟机

查看字符集：echo  $LANG

临时修改字符集（立即生效，重新登录系统失效）：export LANG=zh_CN.UTF-8或LANG=zh_CN.UTF-8

注：只要修改环境变量就必须在前面加“export”

    中文字符集：zh_CN.UTF-8

    英文字符集：en_US.UTF-8

永久修改字符集（source或.或重启生效）：修改配置文件/etc/sysconfig/i18n

修改完后：使用source  /etc/sysconfig/i18n 使其生效

[root@centos ~]# echo $LANG
en_US.UTF-8
[root@centos ~]# echo $(LANG)
-bash: LANG: command not found
[root@centos ~]# export LANG=en
[root@centos ~]# echo $LANG
en
[root@centos ~]# LANG=en
[root@centos ~]# echo $LANG
en
[root@centos ~]# cat /etc/sysconfig/i18n 
LANG="en_US.UTF-8"

SYSFONT="latarcyrheb-sun16"

[root@centos ~]# vi  /etc/sysconfig/i18n 

[root@centos ~]# . /etc/sysconfig/i18n 
[root@centos ~]# source /etc/sysconfig/i18n
[root@centos ~]# cat /etc/sysconfig/i18n
LANG="zh_cn.UTF-8"

SYSFONT="latarcyrheb-sun16"

命令行参数补齐

最小化安装centos6.9，无法直接使用yum安装bash-completion。先安装EPEL (Extra Packages for Enterprise Linux)

yum provides epel*   *completion  查找

yum install epel-release -y            安装epel源

yum install bash-completion -y

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