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  • 9.28 linux系统基础优化

    • 关闭SELinux(是美国安全局对强制访问的实现)功能
    [root@wen ~]# sed -i 's#SELINUX=enforcing#SELINUX=disabled#g' /etc/selinux/config            #使用sed + i 命令修改
    [root@wen ~]# grep "SELINUX=disabled" /etc/selinux/config                                    #grep查看
    SELINUX=disabled
    [root@wen ~]# 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 these two values:
    #     targeted - Targeted processes are protected,
    #     mls - Multi Level Security protection.
    SELINUXTYPE=targeted 
    以上重启生效,生产环境不能重启
    
    用以下命令不用重启 
    [root@wen ~]# getenforce
    Enforcing
    [root@wen ~]# setenforce
    usage: setenforce [ Enforcing | Permissive | 1 | 0 ]
    [root@wen ~]# setenforce 0
    [root@wen ~]# getenforce
    Permissive
    • 运行级别
    [root@wen ~]# cat /etc/inittab
    # inittab is only used by upstart for the default runlevel.
    #
    # ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
    #
    # System initialization is started by /etc/init/rcS.conf
    #
    # Individual runlevels are started by /etc/init/rc.conf
    #
    # Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
    #
    # Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
    # with configuration in /etc/sysconfig/init.
    #
    # For information on how to write upstart event handlers, or how
    # upstart works, see init(5), init(8), and initctl(8).
    #
    # Default runlevel. The runlevels used are:
    #   0 - halt (Do NOT set initdefault to this)
    #   1 - Single user mode
    #   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
    #   3 - Full multiuser mode
    #   4 - unused
    #   5 - X11                   #桌面
    #   6 - reboot (Do NOT set initdefault to this)
    # 
    id:3:initdefault:
    
    [root@wen ~]# grep 3:initdefault /etc/inittab          #调整运行级别,默认3,可以调成其他
    id:3:initdefault:
    [root@wen ~]# runlevel                #查看当前级别
    N 3
    [root@wen ~]# init 0                   #切换运行级别
    View Code
    • 关机
    shutdown(halt) init0
    参数
    -r reboot after shutdown
    -h halt or power off after shutdown       
    
    shutdown -h 10    #10分钟后关闭
    shutdown now     #马上
    poweroff                #关闭电源
    
    
    *关闭防火墙
    [root@wen ~]# /etc/init.d/iptables stop                     #临时关闭
    iptables:将链设置为政策 ACCEPT:filter             [确定]
    iptables:清除防火墙规则:                                [确定]
    iptables:正在卸载模块:                                   [确定]
    [root@wen ~]# /etc/init.d/iptables status                   #查看状态
    iptables:未运行防火墙。
    [root@wen ~]# /etc/init.d/iptables restart                  # 重启防火墙           
    iptables:应用防火墙规则:                                [确定]
    [root@wen ~]# chkconfig iptables off                         #开机也不启动了
    • linux中文显示设置等
    *中文显示设置
    [root@wen ~]# echo 'LANG="zh_CN.UTF-8“‘ > /etc/sysconfig/i18n
    [root@wen ~]# cat /etc/sysconfig/i18n
    LANG="zh_CN.UTF-8“
    [root@wen ~]# echo $LANG
    zh_CN.UTF-8
    同时调整ssh客户端
    
    *设置账号超时时间
    [root@wen ~]# export TMOUT=5      #5秒后关机  (临时生效)
    [root@wen ~]# timed out waiting for input: auto-logout
    
    *设置命令行历史记录
    [root@wen ~]# history -c         #清除所有历史记录
    [root@wen ~]# history             #查看历史记录
        1  history
    [root@wen ~]# echo  1
    1
    [root@wen ~]# echo  2
    2
    [root@wen ~]# echo  3
    3
    [root@wen ~]# echo  4
    4
    [root@wen ~]# echo  5
    5
    [root@wen ~]# history -d 3        #删除指定行记录
    [root@wen ~]# history
        1  history
        2  echo  1
        3  echo  3
        4  echo  4
        5  echo  5
        6  history -d 3
        7  history
    [root@wen ~]# !6                 #执行某行历史命令      
    history -d 3
    
    [root@wen ~]# export HISTSIZE=5        #控制历史记录记录数量(临时生效)#永久生效放在/etc/profile文件下,然后source以下/etc/profile
    [root@wen ~]# history
        5  history
        6  echo
        7  history -d 3
        8  export HISTSIZE=5
        9  history
    [root@wen ~]# cat ~/.bash_history         #即使控制了在根目录下还有
    [root@wen ~]# export HISTORYSIZE=5    #命令行命令对应文件的记录数
    
    *隐藏版本信息
    [root@wen ~]# cat /etc/issue
    CentOS release 6.7 (Final)
    Kernel 
     on an m
    
    [root@wen ~]# > /etc/issue
    [root@wen ~]# cat /etc/issue.net
    CentOS release 6.7 (Final)
    Kernel 
     on an m
    [root@wen ~]# >/etc/issue.net
    [root@wen ~]# cat /etc/issue
    [root@wen ~]#
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  • 原文地址:https://www.cnblogs.com/wenyule/p/7609045.html
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