打开终端，查看当前使用的内核；
4 uname -r
5 cat /etc/redhat-release
先更新
6 yum -y update
导入ELRepo仓库的公共密钥
7 rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
安装ELRepo仓库的yum源
8 rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
查询可用内核版本
9 yum --disablerepo=“*” --enablerepo=“elrepo-kernel” list available
安装最新的稳定版本内核
10 yum --enablerepo=elrepo-kernel install kernel-ml-devel kernel-ml -y
查看系统上的所有可用内核：
11 awk -F’ ‘$1=="menuentry " {print $2}’ /etc/grub2.cfg

12 sudo awk -F’ ‘$1=="menuentry " {print i++ " : " $2}’ /etc/grub2.cfg
通过 grub2-set-default 0 命令设置
13 grub2-set-default 0

编辑（e）将GRUB_DEFAULT设置为0，如下
14 vim /etc/default/grub

生成 grub 配置文件并重启
17 grub2-mkconfig -o /boot/grub2/grub.cfg
18 reboot
19 uname -r
删除旧内核
20 rpm -qa | grep kernel
21 yum remove kernel-3* kernel-tools-3*
22 rpm -qa | grep kernel
23 yum -y remove kernel-tools-libs-3.10.0-1160.76.1.el7.x86_64
24 reboot
25 uname -r
26 grub2-set-default 0
27 grub2-mkconfig -0 /boot/grub2/grub.cfg
28 reboot -h now
29 history

查看所有内核选项；
rpm -qa|grep kernel

grub2-set-default 0

进入root模式，删除多余内核；
yum remove 多余内核

重新编译引导；
grub2-mkconfig -o /boot/grub2/grub.cfg

重启；
reboot

安装mysql8.0
https://zhuanlan.zhihu.com/p/486084781

navicat连接报错：Authentication plugin ‘caching_sha2_password’ cannot be loaded的处理方法 - 知乎 https://zhuanlan.zhihu.com/p/97939548

安装python3
yum -y install python36

安装pip

升级pip3:

1.sudo wget https://bootstrap.pypa.io/pip/3.5/get-pip.py
2.sudo python3 get-pip.py
3.pip -V

[root@localhost ~]# wget https://bootstrap.pypa.io/pip/3.5/get-pip.py**
–2022-06-02 15:50:48-- https://bootstrap.pypa.io/pip/3.5/get-pip.py
正在解析主机 bootstrap.pypa.io (bootstrap.pypa.io)… 151.101.108.175, 2a04:4e42:36::175
正在连接 bootstrap.pypa.io (bootstrap.pypa.io)|151.101.108.175|:443… 已连接。
已发出 HTTP 请求，正在等待回应… 200 OK
长度：1908223 (1.8M) [text/x-python]
正在保存至: “get-pip.py”

100%[======================================================================================================================>] 1,908,223 4.20MB/s 用时 0.4s

2022-06-02 15:50:49 (4.20 MB/s) - 已保存 “get-pip.py” [1908223/1908223])

[root@localhost ~]# python3 get-pip.py
Collecting pip<21.0
Downloading pip-20.3.4-py2.py3-none-any.whl (1.5 MB)
|████████████████████████████████| 1.5 MB 676 kB/s
Collecting wheel
Downloading wheel-0.37.1-py2.py3-none-any.whl (35 kB)
Installing collected packages: wheel, pip
Attempting uninstall: pip
Found existing installation: pip 9.0.3
Uninstalling pip-9.0.3:
Successfully uninstalled pip-9.0.3
Successfully installed pip-20.3.4 wheel-0.37.1
[root@localhost ~]# pip install pywinrm>=0.3.0
-bash: /usr/bin/pip: 没有那个文件或目录
[root@localhost ~]# pip -V
-bash: /usr/bin/pip: 没有那个文件或目录

解决方案，执行以下命令：
[root@localhost ~]# hash -r
[root@localhost ~]# pip -V
pip 20.3.4 from /usr/local/lib/python3.6/site-packages/pip (python 3.6)

[root@localhost ~]# pip install pywinrm>=0.3.0
WARNING: You are using pip version 20.3.4; however, version 21.3.1 is available.
You should consider upgrading via the ‘/usr/bin/python3 -m pip install --upgrade pip’ command.

[root@localhost ~]# /usr/bin/python3 -m pip install --upgrade pip
Requirement already satisfied: pip in /usr/local/lib/python3.6/site-packages (20.3.4)
Collecting pip
Downloading pip-21.3.1-py3-none-any.whl (1.7 MB)
|████████████████████████████████| 1.7 MB 675 kB/s
Installing collected packages: pip
Attempting uninstall: pip
Found existing installation: pip 20.3.4
Uninstalling pip-20.3.4:
Successfully uninstalled pip-20.3.4
Successfully installed pip-21.3.1

安装python3

安装依赖
yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel libffi-devel gcc gcc-c++

下载python3
wget https://www.python.org/ftp/python/3.8.3/Python-3.8.3.tgz
tar -zxvf Python-3.8.3.tgz

编译安装
mkdir /usr/local/python3
cd Python-3.8.3
./configure --prefix=/usr/local/python3
make && make install

修改python指向，python2指向python3
rm -rf /usr/bin/python
ln -s /usr/local/python3/bin/python3 /usr/bin/python

修改系统默认pip指向
rm -rf /usr/bin/pip
ln -s /usr/local/python3/bin/pip3 /usr/bin/pip

修复yum
系统指向的python3会导致yum不能正常使用，需要修改为默认python2
vi /usr/bin/yum
把 #! /usr/bin/python 修改为 #! /usr/bin/python2
vi /usr/libexec/urlgrabber-ext-down
把 #! /usr/bin/python 修改为 #! /usr/bin/python2
vi /usr/bin/yum-config-manager
#!/usr/bin/python 改为 #!/usr/bin/python2
没有的不用修改