一、需求说明

  centos官方于2020年12月2号停止了所有centos6更新维护，为了继续享受更新服务，redhat提供了一个redhat-upgrade-tool的升级工具，支持将centos6升级到centos7。centos8停止维护更新时间2021年12月31号，centos7停止更新维护时间为2024年6月30号。centos停止更新后取而代之的是CentOS Stream。
示例环境说明：

• 升级前版本：centos6.5
• 升级后版本：centos7.0

二、升级步骤

0、查看操作系统版本

[root@localhost ~]# cat /etc/centos-release
CentOS release 6.5 (Final)

1、更换YUM源

[root@localhost ~]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://files.tttidc.com/centos6/Centos-6.repo

2、安装升级软件工具

官方下载地址，一般网络从官方下载速度实在是慢得无法忍受。
下载地址一：官网下载地址
下载地址二：>CSDN下载地址
下载rpm包后上传到服务器解压后安装
[root@localhost opt]# yum localinstall preupgrade-assistant-* -y
[root@localhost opt]# yum localinstall redhat-upgrade-tool* -y

3、检测系统可否升级

[root@localhost opt]# preupg -l
CentOS6_7

4、运行模拟升级工具

[root@localhost opt]# preupg -s CentOS6_7
Preupg tool doesn’t do the actual upgrade.
Please ensure you have backed up your system and/or data in the event of a failed upgrade
that would require a full re-install of the system from installation media.
Do you want to continue? y/n
y #此处输入y
Gathering logs used by preupgrade assistant:
All installed packages : 01/11 …finished (time 00:00s)
All changed files : 02/11 …finished (time 02:44s)
Changed config files : 03/11 …finished (time 00:00s)
All users : 04/11 …finished (time 00:00s)
All groups : 05/11 …finished (time 00:00s)
Service statuses : 06/11 …finished (time 00:00s)
All installed files : 07/11 …finished (time 00:02s)
…
Tarball with results is stored here /root/preupgrade-results/preupg_results-210324171443.tar.gz .
The latest assessment is stored in directory /root/preupgrade .
Summary information:
We found some critical issues. In-place upgrade is not advised.
Read the file /root/preupgrade/result.html for more details.
Upload results to UI by command:
e.g. preupg -u http://127.0.0.1:8099/submit/ -r /root/preupgrade-results/preupg_results-*.tar.gz .

5、根据模拟升级的检测结果进行确认和评估

[root@localhost ~]# preupg --riskcheck --verbose
…
INPLACERISK: MEDIUM: We detected some packages installed on the system were removed (obsoleted) between CentOS 6 and CentOS 7. This may break the functionality of the packages depending on them.
INPLACERISK: MEDIUM: We detected some packages installed on the system were removed between CentOS 6 and CentOS 7. This may break the functionality of the packages depending on them.
INPLACERISK: MEDIUM: Package ql2200-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package libudev not provided by its replacement systemd-libs. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package coreutils-libs not provided by its replacement coreutils. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package ql2500-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package ql2100-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package rt61pci-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package ql23xx-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package bfa-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package ql2400-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package rt73usb-firmware not provided by its replacement linux-firmware. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: Package sane-backends-libs-gphoto2 not provided by its replacement sane-backends-drivers-cameras. In-place upgrade might not work properly, will be finished by postupgrade script!
INPLACERISK: MEDIUM: having one of [openscap tzdata redhat-menus kpartx mesa-libGLU] package installed breaks upgrade
INPLACERISK: MEDIUM: We detected some soname bumps in the libraries installed on the system. This may break the functionality of some of your 3rd party applications. They may need rebuild. Please check their requirements.
INPLACERISK: MEDIUM: We detected some .so libraries installed on the system were removed between CentOS 6 and CentOS 7. This may break the functionality of some of your 3rd party applications.
INPLACERISK: SLIGHT: We detected some files where modifications are not tracked in the rpms. You may need to check their functionality after successful upgrade.
INPLACERISK: SLIGHT: We detected some files untracked by rpms. Some of these may need manual check/migration after redhat-upgrade-tool and/or can cause conflicts or troubles during the installation. Try to reduce unnecessary untracked files before running redhat-upgrade-tool.
INPLACERISK: SLIGHT: We detected some packages installed on the system changed their name between CentOS 6 and CentOS 7. Altho h they should be compatible, monitoring after the update is recommended.
INPLACERISK: SLIGHT: export shell commands will be deleted from /etc/sysconfig/sshd
INPLACERISK: SLIGHT: Some binaries untracked by RPM were discovered on the system and may need rebuild after upgrade.
INPLACERISK: SLIGHT: Some scripts untracked by RPM were discovered on the system and may not work properly after upgrade.
INPLACERISK: SLIGHT: /usr/lib64/python2.6/site-packages/gtk-2.0 is owned by an RPM package that was not signed by CentOS.
INPLACERISK: SLIGHT: /usr/lib64/python2.6/site-packages/report is not owned by any RPM package.
INPLACERISK: SLIGHT: /usr/lib64/python2.6/site-packages/reportclient is not owned by any RPM package.

检测评估结果提示风险项，我这是初始化的centos6.5操作系统，风险提示内容都有不少。存在EXTREME错误则无法进行下一步升级操作。

7、安装升级用的centos7 rpm key

[root@localhost ~]# rpm --import http://vault.centos.org/centos/7.0.1406/os/x86_64/RPM-GPG-KEY-CentOS-7
[root@localhost ~]# centos-upgrade-tool-cli --network 7 --instrepo=http://vault.centos.org/centos/7.0.1406/os/x86_64/
setting up repos…
base | 3.7 kB 00:00
base/primary_db | 4.7 MB 00:01

8、运行升级工具

只支持6.5及以上系统升级到不高于7.2系统；

• 1）、直接从网络源进行更新

[root@localhost ~]# centos-upgrade-tool-cli --network 7 --instrepo=http://vault.centos.org/centos/7.0.1406/os/x86_64/
setting up repos…
upgradedevice | 3.6 kB 00:00 …
upgradedevice/primary_db | 2.7 MB 00:00 …
Preupgrade assistant risk check found risks for this upgrade.
You can run preupg --riskcheck --verbose to view these risks.
Addressing high risk issues is required before the in-place upgrade
and ignoring these risks may result in a broken upgrade and unsupported upgrade.
Please backup your data.
…
Continue with the upgrade [Y/N]? y
…
rpm install 100% [============================================================================================]
setting up system for upgrade
Finished. Reboot to start upgrade.

• 2）、从本地源进行更新

  • 下载centos7.0.1406镜像iso文件

  [root@localhost home]# wget https://vault.centos.org/7.0.1406/isos/x86_64/CentOS-7.0-1406-x86_64-DVD.iso

  • 挂载镜像

  [root@localhost home]# mout -o -loop -t iso9660 /home/CentOS-7.0-1406-x86_64-DVD.iso /mnt/cdrom

  • 执行更新

  [root@localhost home]# centos-upgrade-tool-cli --device=/dev/cdrom

9、重启操作系统

[root@localhost home]# reboot

10、查验系统版本

[root@localhost ~]# cat /etc/centos-release
CentOS Linux release 7.0.1406 (Core)

三、FAQ

1、安装redhat-upgrade-tool时报错File contains no section headers.

• 报错信息：
  
• 问题原因：
  repo配置文件错误，缺少配置头信息
• 解决方案：
  -将缺少的yum头信息添加上 [centos6-upgrade]

[root@localhost yum.repos.d]# cat upgradtool.repo.bak
[centos6-upgrade]
name=CentOS-$releasever - Upgrade Tool
baseurl=http://dev.centos.org/centos/6/upg/x86_64/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

2、安装redhat-upgrade-tool时报错Couldn’t resolve host ‘dev.centos.org’

• 报错信息：
  

• 问题原因：
  centos官网已经停止centos6相关服务，网站dev.centos.org已经停止服务。

• 解决方案：
  按照博文步骤，手动安装redhat-upgrade-tool等rpm包。

3、模拟升级时报错

• 报错信息：
  

• 问题原因：
  openscap版本太高，需要降级

• 解决方案：
  卸载当前安装的openscap版本，下载并安装openscap-1.0.8-1.0.1.el6.centos.x86_64.rpm

[root@localhost opt]# rpm -qa |grep openscap
openscap-1.2.13-2.el6.x86_64
[root@localhost opt]# rpm -e --nodeps openscap-1.2.13-2.el6.x86_64
[root@localhost opt]# yum localinstall openscap-1.0.8-1.0.1.el6.centos.x86_64.rpm -y

4、模拟升级的检测结果存在关于X11的EXTREME问题

• 报错信息：
  

• 问题原因：
  centos7对X11桌面环境进行了重新设计

• 解决方案：
  因centos6作为服务器，当前安装软件没有桌面要求，选择卸载X11桌面环境。
  #yum groupremove -y “Desktop” “X Window System”

5、模拟升级的检测结果存在关于pcnet32的EXTREME问题

• 报错信息：
  INPLACERISK: EXTREME: The kernel driver ‘pcnet32’ required to service hardware present in your system is not available in CentOS 7. This suggests that your system contains hardware that is not supported in CentOS 7 release.
• 问题原因：
  vmware 提供的默认网卡类型是pcnet32，el7默认没有提供pcnet32的网卡驱动。
• 解决方案：
  在vmware指定的虚拟机存储位置找到.vmx的文件，
  ethernet0.virtualDev = “pcnet32” 或是别的。将其修改为：
  ethernet0.virtualDev = “e1000”’ （如果没有添加）

四、写着最后

  centos6升级centos7跨越大版本，可能的报错实在是太多，成功的几率也不高，花费的时间成本远远大于新装机centos7的成本。实际中建议新搭建centos7环境测试部署的应用是否兼容，测试通过直接通过新装系统重新部署应用的方式升级。本人仅供学习参考，无法保证升级成功。

MacBook Pro M1芯片 安装Centos8 教程（无界面安装）

Centos8 支持M1芯片下载地址

链接: https://pan.baidu.com/s/17TF3Ah3fXqf8SZshVJMvFg 提取码: 0d8v

0、Linux关机命令

CentOS使用halt关机出现system halting卡死
使用如下命令解决方法：

使用 halt -p 			正常关机不会出现 system halting
使用 shutdown -h now 	正常关机不会出现 system halting
使用 systemctl poweroff 	正常关机不会出现 system halting

1、安装截图

安装环境：2021款M1MacBookPro，macOS Monterey 12系统 Apple M1芯片
安装时间：2021年12月02日

• 选择安装
  

• 第一次输入r，刷新配置，可以看到有几个带感叹号⚠️的警告，接下来就一一设置
  

• 磁盘选择设置，先选数字5 再按提示c c c，完成磁盘的选择，如下图：
  

• 设置root密码，先选数字8 再按提示6688...，完成密码设置，如下图：
  
  

• 输入b 后可以看到已经开始安装了，等着就好…
  

• 安装完成！
  

2、安装完成重启后提示如下警告⚠️：

解决办法：

若出现license information(license not accepted)，即说明需要同意许可信息，
输入1-回车-2-回车-c-回车-c回车，即可解决。

其他两项，创建用户 和 网络配置 ，可以后面操作，无关紧要

上面选择q退出，yes确认后进入登录界面，输入用户：root、密码：6688…（密码是在安装过程已经设置好的）

3、配置网络（由于在安装过程中没有配置网络，默认是关闭）

3.1 编辑网络配置文件

cd /etc/sysconfig/network-scripts/
ls

• 如下图，ifcfg- 开头的就是我们要编辑的配置文件，每个人的文件名可能不同

• 修改ONBOOT=yes #开机自启

TYPE=Ethernet  #网卡类型
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=dhcp #动态获取
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
NAME=enp0s5
UUID=cd9c7deb-5cf8-4474-abf2-b06cf1bafc07
DEVICE=enp0s5 #设备名
ONBOOT=yes

• 保存退出后，重启网络或者重启CentOS 命令：shutdown -h now：

systemctl restart network.service

• 查询IP地址 ip addr，可以看到我们已经成功了

• 进一步验证网络，测试百度curl www.baidu.com， 测试通过！

3.2 配置静态IP，并能够通过 SSH 连接

选择共享网络–再点开配置–网络–高级设置–打开网络首选项

• 修改配置文件：vi /etc/sysconfig/network-scripts/ifcfg-enp0s5
• 这一步和上面一样，注意ifcfg-开头的文件可能名字不同

# 修改为静态IP dhcp为动态ip none为无
BOOTPROTO=static
# IP地址
IPADDR=10.211.55.3
# 网关
GATEWAY=10.211.55.1
# 子网掩码
NETMASK=255.255.255.0
# 从no改成yes。系统将在启动时自动开启该接口
ONBOOT=yes
# DNS服务器1、2
DNS1=10.211.55.1
DNS2=8.8.8.8

• 修改完后重启网络

systemctl restart network 或 service network restart

• 显示 OK表示成功，如果重启失败，如下图报错，可以尝试重启虚拟机 reboot 再尝试ping一下电脑ip
• 关于这个报错具体解决办法可以参考：https://www.codeleading.com/article/34552269276/

• 这里简单说下我的解决办法：
• centos8 不能重启网络报错原因 Failed to restart network.service: Unit network.service not found
• 由于 centos8 已经替换了原来的network, 新版的叫：NetworkManager
• 所以用这个命令就可以重启了 systemctl restart NetworkManager
• 重启后查询运行状态：systemctl status NetworkManager

● NetworkManager.service - Network Manager
   Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2021-12-01 10:24:49 EST; 30s ago
     Docs: man:NetworkManager(8)
 Main PID: 1585 (NetworkManager)
    Tasks: 3 (limit: 8530)
   Memory: 3.0M
   CGroup: /system.slice/NetworkManager.service
           └─1585 /usr/sbin/NetworkManager --no-daemon

Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0732] device (enp0s5): state change: config -> ip-config (reason 'none', sys-iface-state: 'assume')
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0735] device (enp0s5): state change: ip-config -> ip-check (reason 'none', sys-iface-state: 'assume')
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0754] device (enp0s5): state change: ip-check -> secondaries (reason 'none', sys-iface-state: 'assume')
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0755] device (enp0s5): state change: secondaries -> activated (reason 'none', sys-iface-state: 'assume')
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0756] manager: NetworkManager state is now CONNECTED_LOCAL
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0758] manager: NetworkManager state is now CONNECTED_SITE
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0759] policy: set 'enp0s5' (enp0s5) as default for IPv4 routing and DNS
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0774] device (enp0s5): Activation: successful, device activated.
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0776] manager: NetworkManager state is now CONNECTED_GLOBAL
Dec 01 10:24:49 localdomain NetworkManager[1585]: <info>  [1638372289.0777] manager: startup complete

ping 10.211.55.3

• 成功效果图：

ssh root@10.211.55.3

4、关闭防火墙

查看防火墙状态：firewall-cmd --state或systemctl status firewalld.service

关闭：systemctl stop firewalld.service

永久关闭： systemctl disable firewalld.service

永久关闭效果图

5、在M1芯片的MacBook上centos8安装Parallels Tools

• 首先配置网络，后面需要用到
• Parallels安装好CentOS，需要共享Mac文件夹同样需要安装Parallels Tools。
  跟Windows不同的，CentOS不会自动弹出安装界面，需要你手动安装。

5.1、加载Parallels Tools安装文件

5.2、回到虚拟机里，执行挂载光盘：

[root@localdomain ~]# mount /dev/cdrom /mnt
mount: /mnt: WARNING: device write-protected, mounted read-only.
[root@localdomain ~]# df -h /mnt/
Filesystem      Size  Used Avail Use% Mounted on
/dev/sr0         60M   60M     0 100% /mnt
[root@localdomain ~]# cp -ra /mnt /opt/
[root@localdomain ~]# umount /mnt
[root@localdomain ~]#

5.3、选择光盘

修改源文件
一般我都是保留必须的，其它的先弄其它地方放着

[root@localdomain ~]# mv /etc/yum.repos.d/CentOS-* /opt/
[root@localdomain ~]# mv /opt/CentOS-Linux-Media.repo /etc/yum.repos.d/
[root@localdomain ~]# mkdir /media/CentOS/ -p
[root@localdomain ~]# mount /dev/cdrom /media/CentOS/
mount: /media/CentOS: WARNING: device write-protected, mounted read-only.
[root@localdomain ~]# df -h|grep /media/CentOS
/dev/sr0                    6.8G  6.8G     0 100% /media/CentOS

上面的注意检查下，是这个6.8G的，之前的那个tool的要umount掉，然后再操作上面的iso加载，不行就多操作或者重启机器了

修改vim /etc/yum.repos.d/CentOS-Linux-Media.repo文件如下，centos7的是一个，注意这里centos8已经拆分成两个了

CentOS-Linux-Media.repo 原始文件如下

# CentOS-Linux-Media.repo
#
# You can use this repo to install items directly off the installation media.
# Verify your mount point matches one of the below file:// paths.

[media-baseos]
name=CentOS Linux $releasever - Media - BaseOS
baseurl=file:///media/CentOS/BaseOS
        file:///media/cdrom/BaseOS
        file:///media/cdrecorder/BaseOS
gpgcheck=0
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

[media-appstream]
name=CentOS Linux $releasever - Media - AppStream
baseurl=file:///media/CentOS/AppStream
        file:///media/cdrom/AppStream
        file:///media/cdrecorder/AppStream
gpgcheck=0
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

• 添加epel源
  这个是因为dkms的包是在epel里面的，而tool是需要这个dkms的包的，所以添加源
  而gcc的默认的版本已经足够高了，不需要之前centos7的那些处理

修改后整个文件/etc/yum.repos.d/CentOS-Media.repo内容如下：

# CentOS-Linux-Media.repo
#
# You can use this repo to install items directly off the installation media.
# Verify your mount point matches one of the below file:// paths.

[media-baseos]
name=CentOS Linux $releasever - Media - BaseOS
baseurl=file:///media/CentOS/BaseOS
#        file:///media/cdrom/BaseOS
#        file:///media/cdrecorder/BaseOS
gpgcheck=0
enabled=1
#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

[media-appstream]
name=CentOS Linux $releasever - Media - AppStream
baseurl=file:///media/CentOS/AppStream
#        file:///media/cdrom/AppStream
#        file:///media/cdrecorder/AppStream
gpgcheck=0
enabled=1
# gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

[epel]
name=epel
baseurl=https://mirrors.tuna.tsinghua.edu.cn/epel/8/Everything/aarch64/
gpgcheck=0
enabled=1

5.4、更新yum缓存 yum makecache

[root@localdomain ~]# yum makecache
Failed to set locale, defaulting to C.UTF-8
CentOS Linux 8 - Media - BaseOS                                                                                                           317 MB/s | 1.5 MB     00:00
CentOS Linux 8 - Media - AppStream                                                                                                        561 MB/s | 6.0 MB     00:00
epel                                                                                                                                      7.2 MB/s |  11 MB     00:01
Metadata cache created.

5.5、开始安装 Parallels Tools

[root@localdomain ~]# cd /opt/mnt/
[root@localdomain mnt]# ll
total 536
-r-xr-xr-x. 1 root root   1043 Nov 24 14:24 install
-r-xr-xr-x. 1 root root 533104 Nov 24 14:25 install-gui
dr-xr-xr-x. 3 root root   4096 Nov 24 14:25 installer
dr-xr-xr-x. 2 root root     28 Nov 24 14:24 kmods
dr-xr-xr-x. 4 root root    185 Nov 24 14:25 tools
-r--r--r--. 1 root root     13 Nov 24 14:25 version
[root@localdomain mnt]# ./install

说明一下，我这里是用iTerm连接的虚拟机，所以安装界面没有颜色
因为我上面IP已经配置为静态，命令：ssh root@10.211.55.3

一路下一步，直到弹出成功的提示，然后重启机器！

• 检查是否真的安装好了，安装好了有共享文件夹功能，可以在linux里面直接访问Mac的文件

• 添加共享文件夹

• 查看共享文件夹的文件
• 可以看到上面我共享的目录直接就可以在虚拟机里面访问了，到这里全部就安装好了

[root@localdomain ~]# ls /media/psf/Downloads/

安装总结

• 主要的步骤
• 准备好iso的源，添加一个epel源即可

6、通过 yum 安装一些基本软件

• net-tools 提供dig, nslookup, ifconfig等，用于配置网络：

yum install net-tools

• 添加 wget 下载文件：

yum install wget

7、更换 yum 源

repo文件下载地址：

网易:http://mirrors.163.com/.help/…
阿里:http://mirrors.aliyun.com/

1. 备份：

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 6

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo

或者

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo

CentOS 7

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo

或者

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo

CentOS 8

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-8.repo

或者

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-8.repo

3. 清除文件 并 重建元数据缓存

yum clean all
yum makecache

4. 最后更新软件包

yum update -y

5. 其他
   非阿里云ECS用户会出现 Couldn’t resolve host ‘mirrors.cloud.aliyuncs.com’ 信息，不影响使用。用户也可自行修改相关配置: eg:

sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo

yum 源配置完成

相关链接：阿里云CentOS 镜像

6. yum makecache 出现报错

• 报错：Errors during downloading metadata for repository 'media-baseos': …

[root@localdomain ~]# yum makecache
Failed to set locale, defaulting to C.UTF-8
CentOS-8 - Base - mirrors.aliyun.com                                                                                  3.9 MB/s | 2.9 MB     00:00
CentOS-8 - Extras - mirrors.aliyun.com                                                                                 38 kB/s |  10 kB     00:00
CentOS-8 - AppStream - mirrors.aliyun.com                                                                             1.2 MB/s | 6.9 MB     00:05
CentOS Linux 8 - Media - BaseOS                                                                                       0.0  B/s |   0  B     00:00
Errors during downloading metadata for repository 'media-baseos':
  - Curl error (37): Couldn't read a file:// file for file:///media/CentOS/BaseOS/repodata/repomd.xml [Couldn't open file /media/CentOS/BaseOS/repodata/repomd.xml]
Error: Failed to download metadata for repo 'media-baseos': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried
[root@localdomain ~]#

• 解决方法
• 挂载镜像：mount /dev/sr0 /media/CentOS/
• 重新生成缓存 yum makecache

[root@localdomain yum.repos.d]# mount /dev/sr0 /media/CentOS/
mount: /media/CentOS: WARNING: device write-protected, mounted read-only.
[root@localdomain yum.repos.d]# yum clean all
Failed to set locale, defaulting to C.UTF-8
Repository extras is listed more than once in the configuration
33 files removed
[root@localdomain yum.repos.d]# yum makecache
Failed to set locale, defaulting to C.UTF-8
Repository extras is listed more than once in the configuration
CentOS-8 - Base - mirrors.aliyun.com                                                                                  4.7 MB/s | 2.9 MB     00:00
CentOS-8 - Extras - mirrors.aliyun.com                                                                                 33 kB/s |  10 kB     00:00
CentOS-8 - AppStream - mirrors.aliyun.com                                                                             7.6 MB/s | 6.9 MB     00:00
CentOS Linux 8 - AppStream                                                                                            4.6 MB/s | 6.9 MB     00:01
CentOS Linux 8 - BaseOS                                                                                               2.5 MB/s | 2.9 MB     00:01
CentOS Linux 8 - Media - BaseOS                                                                                       279 MB/s | 1.5 MB     00:00
CentOS Linux 8 - Media - AppStream                                                                                    487 MB/s | 6.0 MB     00:00
epel                                                                                                                  7.5 MB/s |  11 MB     00:01
Metadata cache created.
[root@localdomain yum.repos.d]#

8、创建一个普通用户并赋予 root 权限

用普通账号进行登录可以避免 root 用户进行错误操作，而且用普通用户登录就像给服务器建立了两道墙，必须先用普通用户登录再设置能用 root 账号登录，所以后面还要配置禁止 root 用户通过 SSH 登录。

• 创建普通用户

[root@localdomain ~]# useradd -d /usr/able -m able
# 新增用户,其中 -d 和 -m 是为用户 able 产生一个主目录  /usr/able


[root@localdomain ~]# passwd able           # 为新增用户修改密码
Changing password for user able.
New password:                               # 输入密码
BAD PASSWORD: The password fails the dictionary check - it does not contain enough DIFFERENT characters
Retype new password:                        # 确认密码
passwd: all authentication tokens updated successfully.
[root@localdomain ~]#

这个普通用户有时也需要使用 root 权限，所以讲他加入到sudoers 用户组，
允许其使用sudo临时调用 root 权限

[root@localdomain etc]# echo 'able ALL=(ALL) ALL'>> /etc/sudoers
[root@localdomain etc]# tail -1 /etc/sudoers
able ALL=(ALL) ALL
[root@localdomain etc]#

9、禁止 root 使用 ssh 登入

进入配置文件：

/etc/ssh/sshd_config

找到如下语句进行修改

PermitRootLogin yes

把它改成

PermitRootLogin no

重启 sshd

systemctl restart sshd.service

这样别人就要必须要获取普通用户账号密码，然后才能破解 root

最后喜欢的小伙伴，记得关注收藏哦！😏🍭😘

参考文章

参考文章1：在m1芯片的MacBook上安装centos7
参考文章2：在m1芯片的MacBook上centos7安装parallels tool
参考文章3：在m1芯片的MacBook上安装centos8
参考文章4：在m1芯片的MacBook上centos8安装parallels tool
参考文章5：CentOS 7 在 Parallels 中的安装及基本配置

centos 实现自动运行 Python 脚本

正式配置前，先编写一段 Python 脚本，实现日志写入文件操作

import os
import sys
import logging

current_path = os.getcwd() # 获取当前目录
logging.basicConfig(level=logging.INFO,  
                    filename=current_path + '/new.log',
                    filemode='a',
                    format='%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s'
                    )
logging.info("写入日志")

centos中测试定时任务

使用 crontab 进行定时任务的处理，如果没有安装可以自行百度进行设置。
在正式使用 crontab 前，需要提前了解一下 crond ， crond 和 crontab 是密切相关了， crond 是 linux 中用来周期性的执行某种任务或等待处理某些事件的一个守护进程，与windows的计划任务类似， crontab 是一个编辑或者说是管理定时任务的工具。
简单理解就是 crond是一个服务，crontab是一个命令。

与之相关的命令有

yum install crontabs
systemctl enable crond （开机启动）
systemctl start crond（启动 `crond` 服务）
systemctl stop crond（停止服务）
systemctl restart crond  （重启服务）
systemctl reload  crond （重载配置文件）
systemctl status crond （查看状态）

测试状态之后，展示为 active(running) 即表示成功。

crontab文件
用户所建立的crontab文件中，每一行都代表一项任务，每行的每个字段代表一项设置，它的格式共分为六个字段，前五段是时间设定段，第六段是要执行的命令段，格式如下：

minute hour day month week command

在正式开始前，可以使用 crontab -l 查看一下已经开启了哪些定时任务。

crontab -l

其余 crontab 常见的命令如下：

• crontab -u：设定某个用户的crond服务
• crontab -e：编辑crontab文件(编辑定时任务)
• crontab -r ：删除crontab文件(删除定时任务)
• crontab -i ：删除crontab文件提醒用户(删除定时任务)

详细配置
上文已经提及了一个定时任务的6个字段，其取值分别为：

minute hour day month week command

上述字段分别是：分，时，日，月，周，命令

• 第1列表示分钟1～59 每分钟用 * 或者 */1 表示；

• 第2列表示小时1～23（0表示0点）；

• 第3列表示日期1～31；

• 第4列表示月份1～12；

• 第5列标识号星期0～6（0表示星期天）；

• 第6列要运行的命令；

• *：任意时间，可以代表00-23小时或者00-12每月或者00-59分，例如 0 9 * * * cmd 表示每月每周每日的 9:00 都执行cmd任务；

• -：表示区间，是一个范围，例如 00 17-19 * * * cmd，就是每天17, 18, 19点的整点执行命令；

• ,：是分割时段，例如 30 1,3,5 * * * cmd，就是每天凌晨1点30，3点30，5点30都执行命令；

• /n：n 为数字，表示分割，每隔 n 单位时间，可以看成除法，*/6 * * * * cmd，每隔6分钟执行一次。

设置定时任务
crontab -e ：直接写入定时任务

*/1 1-2 * * * root /usr/bin/python3 /var/test1.py
*/1 1-2 * * * root /usr/bin/python3 /var/test2.py

vim /etc/crontab ：文件形式添加任务

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed
1 * * * * /usr/bin/python3 /usr/test/test.py

重新加载配置

service crond reload

重启cron

service crond restart

两种方法的区别
crontab -e 对应的是用户级， vim /etc/crontab 对应的系统级的。
crontab -e 与 vim /etc/crontab 修改语法格式不一样，后者多一个user指定。

查看文件的权限

ls /etc/crontab -lh

查看任务是否添加

crontab -l -u root

在 centos 查找文件

find / -name xxxx.conf # 在根目录查找
find /var -name xxxx.conf # 在 var 目录查找

记录时间

2022年度 Flag，写作的 564 / 1024 篇。
可以关注我，点赞我、评论我、收藏我啦。

更多精彩

• Python 爬虫 100 例教程导航帖（连续 3 年，不断更！）
• Python爬虫120 （39.9 元，保 5 年更新）