System Mirror Name: ubuntu-18.04.5-desktop-amd64.iso
System Kernel Version: 5.4.0-42-generic (uname -r)
Mirror download address: magnet:?xt=urn:btih:94A315E2CF8015B2F635D79AAB592E6DB557D5EA (use Thunder New Download )
1. Common commands
Update the list of installation sources
sudo apt-get update
update installed software
sudo apt-get upgrade
install python3.8
sudo apt-get install python3.8
view python3.8 installation location
which python3.8
remove python3.8 (Retain configuration files)
sudo apt-get remove python3.8
remove python3.8 (delete configuration files)
sudo apt-get purge python3.8
remove python3.8 (retain configuration files/remove dependencies)
sudo apt-get remove- -auto-remove python3.8
remove python3.8 (delete configuration file/delete dependency)
sudo apt-get purge --auto-remove python3.8
remove /var/cache/apt/archives/ deb package
sudo apt-get clean
sudo apt-get autoclean
Check the remaining disk space
df -hl
Use the telnet protocol to connect to the server
telnet ip port
2. Install and configure python
installation pip
sudo apt-get install python-pip python-dev build-essential
sudo pip install --upgrade pip
install pip3
sudo apt-get install python3-pip python3-dev build-essential
Configure pip installation source
Create new
~/.pip/pip.conf
write
[global]
trusted-host = mirrors.aliyun.com
index-url = http://mirrors.aliyun.com/pypi/simple
Set the default python version
View the installed python version
ls /usr/bin/python* 
Set the python version priority
sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 3
Set the current version of python
sudo update-alternatives --config python 
view the configured python version
sudo update-alternatives --list python 
3. firewall settings
view firewall status
sudo ufw status
turn on the firewall
sudo ufw enable
turn off the firewall
sudo ufw disable 
4. Install and configure google chorme
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo dpkg -i google-chrome-stable_current_amd64.deb
5. Install and configure wireshark
sudo groupadd wireshark
sudo chgrp wireshark /usr/bin/dumpcap
sudo chmod 4755 /usr/bin/dumpcap
sudo gpasswd -a xinglei wireshark
6. Install Sogou Pinyin input method (only installed in ubuntu-18.04.5)
Download page: https://pinyin.sogou.com/linux/? r=pinyin
installation method: https://pinyin.sogou.com/linux/help.php