System

check your system, refer to https://www.huaweicloud.com/articles/1d7ee487bde77c3df14d144f4c0c136c.html

cat /etc/*release && uname -m
uname -a
# number of CPUs, cpu cores, logic processors, type
cat /proc/cpuinfo| grep "physical id"| sort| uniq| wc -l
cat /proc/cpuinfo| grep "cpu cores"| uniq
cat /proc/cpuinfo| grep "processor"| wc -l
cat /proc/cpuinfo | grep name | cut -f2 -d: | uniq -c

User

# show all users
cat /etc/passwd
# current user
whoami
# change user password
# for the first time to `sudo passwd`, current root password is the installation user password, valid after restart PC
sudo passwd [root]
passwd [current user]
# su: substitute user, use `man su` for more help
su [root]
su - [root]
sudo su root
# Linux中创建非root用户，并授权对某个应用的操作权限，https://blog.csdn.net/panchang199266/article/details/86765007
# 以root用户来创建新的用户 ， groupadd 添加一个用户组
[root@localhost home]# groupadd elk
# 添加一个用户，-g是在用户组下 -p是密码
[root@localhost home]# useradd elk -g elk -p elk
# 进入es的安装目录
[root@localhost home]# cd /home/elasticsearch 
# 给用户elk授权
[root@localhost home]# chown -R elk:elk elasticsearch-6.3.1/
# 切换到 elk用户
[root@localhost elasticsearch]# su elk
# add to sudo group
# su
# vi /etc/sudoers
# wq!

related: Linux下修改用戶模式（usermod，sudo權限等）.

root

Source

apt

su
cd
cd /etc/apt
ll
vim sources.list
cp sources.list sources.list.bak
>sources.list
vim sources.list

pip

cd
mkdir .pip
cd .pip
vim pip.conf
cd

pip source: https://support.huaweicloud.com/instg-cli-cann503-alpha002/atlasdeploy_03_0071.html#ZH-CN_TOPIC_0000001197460367

Install dependency

offline

you can install some basic tools or libraries offline by using Ubuntu installation file, like ubuntu-18.04.5-desktop-amd64.iso, refer to Ubuntu-离线安装基本依赖（gcc、make、dkms等）_快乐学术猿-CSDN博客_ubuntu安装dkms.

sudo dpkg -i ***.deb

Notice: not suggested because of the old versions and special installation order.

online

sudo apt-get update
sudo apt-get upgrade
sudo apt install build-essential

sudo apt --fix-broken install

pip3 install --upgrade pip

hosts and proxy

for faster access

local site

refer to ubuntu加速github - Jarvis_Xu - 博客园 (cnblogs.com),

search DNS of github.global.ssl.fastly.net and assets-cdn.github.com in http://tool.chinaz.com/dns/.

sudo gedit /etc/hosts
# search one by one and modify the file
# after modifying
/etc/init.d/networking restart

system

use clash for Linux: A rule-based tunnel in Go.

Using the following instruments, download and extract software clash from Releases · clash, and move the executable file to be customized /usr/local/bin/clash, then execute it to automatically get ~/.config/clash and two configuration file in it.

export VERSION_CLASH=v1.6.5
export CLash_VERSION=clash-linux-amd64-${VERSION_CLASH}
wget https://github.com/Dreamacro/clash/releases/download/${VERSION_CLASH}/${CLash_VERSION}.gz
ls
sudo gzip -d ${CLash_VERSION}.gz
export CLASH=/usr/local/bin/clash
sudo mv ${CLash_VERSION} ${CLASH}
sudo chmod +x ${CLASH}
# run clash to create a default ~/.config/clash/
sudo ${CLASH}
cd ~/.config/clash
ls

Press Ctrl + C to stop clash.

Notice: you can build locally referring to Home · Dreamacro/clash Wiki · GitHub.

Update your own config.yaml to ~/.config/clash/config.yaml,

export CLASH_URL={your own subscription address}
sudo wget --no-check-certificate -O ~/.config/clash/config.yaml ${CLASH_URL}
# or
# curl -L -o ~/.config/clash/config.yaml ${CLASH_URL}
# or, refer to https://blog.csdn.net/Undefinedefity/article/details/117171436
# curl -H "User-Agent: ClashX/1.20.4.1" https://*****.yaml > config.yaml

Optional: you can update the ~/.config/clash/Country.mmdb too, use the following command lines or download from GeoLite2-Country.mmdb · Gitee 极速下载/Pingtunnel - Gitee.com.

export Countrymmdb_URL=https://www.sub-speeder.com/client-download/Country.mmdb>
# or
export Countrymmdb_URL=https://whiter.cc/cached-apps/linux/Country.mmdb
wget --no-check-certificate -O ~/.config/clash/Country.mmdb ${Countrymmdb_URL}

Configure Ubuntu system proxy responding to ~/.config/clash/config.yaml,
gedit ~/.config/clash/config.yaml
suggest to use GUI in Settings -> Network -> Network Proxy -> Manual, or use shell command lines referring to Linux下安装&配置Clash以实现代理上网 - 知乎 (zhihu.com).
Configure clash in external controller with a browser, refer to Clash For Linux 安装及使用.
Set automatical action, like Boot and Update. you can refer to 在 Ubuntu 上使用 clash 代理工具_dongheli的专栏-CSDN博客, Ubuntu 18.04 使用clash_Undefinedefity的博客-CSDN博客, and Linux下安装&配置Clash以实现代理上网 - 知乎 (zhihu.com). Some frequent usage:
systemctl status clash systemctl start clash systemctl kill clash
Notice: if you plan to write a systemd unit .service yourself, you need to put it at /lib/systemd/system on Ubuntu and use an absolute path to an executable or a simple file name without any slashes while writing ExecStart=, for example you cannot use ~, refer to systemd.service (www.freedesktop.org). Besides, you must use systemctl daemon-reload in shell to make changes and modification of .service valid, refer to How to Manage ‘Systemd’ Services and Units Using ‘Systemctl’ in Linux (tecmint.com) and 技术|systemctl 命令完全指南 (linux.cn).

Otherwise, you can use a native software Startup Application, refer to Ubuntu 18.04 使用clash_Undefinedefity的博客-CSDN博客.
echo ${CLASH}

set for terminal

export http_proxy=http://127.0.0.1:7890
export https_proxy=http://127.0.0.1:7890

Notice: if your system time is not correct, there would be something wrong with clash.

shell

how to execute .sh file, refer to ubuntu执行.sh文件几种方式区别_yao伟斌-CSDN博客.

command lines syntax, echo和Shell特殊变量：Shell $0, $#, $*, $@, $?, $$和命令行参数_weixin_33890499的博客-CSDN博客.

apt-get

sudo apt update
sudo apt-get install git
# refer to https://gauliang.github.io/blog/2020/how-to-install-java-with-apt-get-on-ubuntu/
sudo apt install default-jre

refer to 2020最详细安装Ubuntu指南 - 知乎 (zhihu.com), ubuntu新安装完成后配置_sinat_40025092的博客-CSDN博客,

chmod

# Executable permission
chmod +x A*

ln

ln -s {src} {des}

tar gz tgz

refer to Ubuntu 常用解压与压缩命令_songbinxu的博客-CSDN博客_ubuntu zip,

# .tgz & .tar.gz 
tar -zxvf FileName.tar.gz -C DesDirName
# .zip
unzip FileName.zip -d DesDirName
zip -r FileName.zip srcName
# .tar
tar -xvf FileName.tar
# .gz
gunzip FileName.gz

makefile

refer to MakeFile 文件的使用 - CTHON - 博客园 (cnblogs.com), Makefile的使用方法 - linqiaozhou - 博客园 (cnblogs.com), https://www.jianshu.com/p/c70afbbf5172:

./configure --prefix=/usr
make
sudo make install

directory store

pwd
mkdir
rm -rf
rm -rf {directory name}/*

# Ubuntu查看文件大小或文件夹大小
du -lh --max-depth=1
ls -l filename
du -sh filename
# 查看磁盘的使用情况命令：
df -h

swap

refer to https://zhuanlan.zhihu.com/p/399986218, Linux环境下swap配置方法 - 腾讯云开发者社区-腾讯云

# check swap and disk
free -h
df -h
# create swapfile which occupys disk, e.g. 64GB
dd if=/dev/zero of=/var/swapfile bs=1M count=65536

mkswap /var/swapfile
swapon /var/swapfile
swapon -s

# open /etc/fstab
vim /etc/fstab
# add following at last:
/var/swapfile swap swap defaults 0 0

# check swappiness
cat /proc/sys/vm/swappiness

file

refer to Linux vi/vim | 菜鸟教程 (runoob.com), linux下的Source命令的基本功能_百度知道 (baidu.com),

touch
vim
# d delet line
source
rm -rf ./
cat

tree

sudo apt-get install tree
tree .

process

# refer to https://blog.csdn.net/andy572633/article/details/7211546
ps -aux | grep 46730
ps -fe
ps -ef | grep cyber_monitor{name of process}
pgrep {name of process}

kill {PID of process}
kill -s 9 {PID of process}
pkill - 9 {name of process}

nohup

# https://www.runoob.com/linux/linux-comm-nohup.html
# https://blog.51cto.com/u_15088375/3247580
nohup /root/runoob.sh &
nohup /root/runoob.sh > runoob.log 2>&1 &

ps -aux | grep "runoob.sh" 
# ps -def | grep "runoob.sh"
kill -9  进程号PID

cpu

# refer to https://www.cnblogs.com/ggjucheng/archive/2012/01/08/2316399.html
top

Environment Variables

refer to ubuntu－设置系统环境变量 - 简书 (jianshu.com),

IP

ifconfig -a

PORT

lsof -a -i4 -i6 -itcp
lsof -i TCP:2000

system

sudo vim ~/.bashrc

driver

ubuntu-drivers devices
sudo ubuntu-drivers autoinstall

ssh

# refer to https://bicmr.pku.edu.cn/~wenzw/pages/filetransfer.html
# sshfs, refer to https://cloud.tencent.com/developer/article/1168897
sudo apt install sshfs
mkdir ~/workstation
sshfs username@ip_address: ~/workstation
fusermount -u workstation
# scp
scp file username@ip_address:Documents/
scp -rf folder username@ip_address:

root

refer to ubuntu18.04获取root权限并用root用户登录 - 不妨不妨，来日方长 - 博客园 (cnblogs.com),

setting -> privacy -> screen lock

refer to Ubuntu20.04 桌面共享 - Beavan - 博客园 (cnblogs.com), Win10远程桌面Ubuntu20.04 - 掘金 (juejin.cn).

# 1 screen sharing in setting, if no setting install vino
sudo apt install vino
# 2 dconf-editor->org->gnome->desktop->remote access->require encrytion: turn off
sudo apt install xrdp dconf-editor
# 3 login using IP, tool.lu/ip/

Application

# refer to https://code.visualstudio.com/docs/setup/linux
# install deb file
sudo apt install ./<file>.deb

# If you're on an older Linux distribution, you will need to run this instead:
sudo dpkg -i <file>.deb
# Install dependencies
sudo apt-get install -f