用户管理

非 sudo 用户

xxx is not in the sudoers file. This incident will be reported

解决办法：

1. 使用 visudo 编辑 sudo 配置文件

2. 找到该行:

    root ALL=(ALL) ALL
   

3. 在改行下插入新行, 为指定用户授予权限:

    xxx  ALL=(ALL) ALL
   

4. 保存并退出即可生效

软件使用

链接失效

too many levels of symbolic links

解决办法：建立链接时请使用绝对路径。

软件配置

Apt 软件源

Ubuntu

1. 备份

    sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
   

2. 修改软件源文件

    sudo vim /etc/apt/sources.list
   

3. 修改内容为：

    ###### Ali source 20190909 ######
    deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
    deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
    deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
    deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
    deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
    deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
    deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
    deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
    deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
    deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
    #################################
   

4. 试试是否生效，试试就逝世

    apt-get update
   

CentOS

1. 改名备份原源文件

    mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
   

2. 下载新的CentOS-Base.repo 到/etc/yum.repos.d/

    # CentOS 5
    wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo
    # CentOS 6
    wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
    # CentOS 7
    wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
   

3. 生成缓存，试试是否生效，试试就逝世

    yum makecache
   

SSH

安装和启用

1. 安装 openssh-server

    sudo yum install openssh-server
   

2. 配置 openssh，编辑：/etc/ssh/sshd_config，开启以下配置：

    Port 22
    ListenAddress 0.0.0.0
    ListenAddress ::
    PermitRootLogin yes
    PasswordAuthentication yes
   

3. 启动 ssh 服务

    sudo service sshd start
    # 查看是否开启
    pe -ef | grep sshd
    # 查看端口是否开启
    netstat -an | grep 22
   

开启 RSA 私钥登录

1. 打开 RSA 登录功能，编辑 /etc/ssh/sshd_config：

    RSAAuthentication yes
    PubkeyAuthentication yes
   

2. 在目标主机处生成密钥对

   默认生成路径：~/.ssh，默认生成文件：公钥 id_rsa.pub，私钥 id_rsa

    ssh-keygen
    cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
    chmod 600 ~/.ssh/authorized_keys
    chmod 700 ~/.ssh
    sudo service sshd restart
   

3. 在远程终端处配置

   拉取私钥

    scp $USER@$HOST:~/.ssh/id_rsa ~/.ssh/id_rsa
   

   创建/编辑配置：~/.ssh/config，示例：

    Host zohar
        HostName 192.168.44.134
        User zohar
        StrictHostKeyChecking no
        IdentityFile ~/.ssh/id_rsa
   

4. 登录测试

    ssh zohar
    PS C:\Users\TopOn\.ssh> ssh zohar
    Last login: Sun Apr 26 14:47:52 2020 from 192.168.44.1
    [zohar@localhost ~]$
   

关闭/开启图形界面

CentOS 7

CentOS7 用 target 取代了运行级别的概念，使用以下命令开关图形界面：

# 查看当前配置
sudo systemctl get-default
# 配置多用户命令行模式
sudo systemctl set-default multi-user.target
# 配置图形界面模式
sudo systemctl set-default graphical.target

卸载图形界面

// X window
sudo yum groupremove "X Window System"
// GNOME
sudo yum groupremove "GNOME"
sudo yum groupremove "GNOME Desktop Enviroment"
// KDE
sudo yum groupremove "KDE"