Ubuntu commands (updated all the time)

install software:apt-get install <appName>
- whereis <appName>: View the software installation location;
- wget <web:url软件下载地址>: Download the software installation package through the network;
- apt --purge remove <appName>: Uninstall the software

sshThe installation starts:sudo apt-get install ssh sudo systemctl start
- View sshstartup status:ps -aux|grep sshd

2.1 安装 `openssh` 服务端 : `sudo apt-get inistall openssh-server`;
	启动： `sudo /etc/init.d/ssh start`
	查看启动状态： `ps - e |grep ssh`
	- 注意： 启动完成后需要将配置文件 `/etc/ssh/ssh_config` 中的 ‘# PasswordAuthentication yes’ 前的 `#` 号删掉，然后重启服务器；

View the ip address:ifconfig

File editing:

 - `i` 编辑模式；
 - `I`： 在当前光标所在行的行首，转换为输入模式；
 - `a`：在当前光标所在字符的后面，转换为输入模式；
 - `A`：在光标所在的行尾，转换为输入模式；
 - `o`：在当前光标所在行的下方，新建一行，并转为输入模式；
 - `O`：在当前光标所在行的上方，新建一行，并转为输入模式；
 - `s`：删除光标所在字符；
 - `r`：替换光标处字符；

esccommand mode;
- vVISUAL mode (select text), yend selection;
- dcut line

Cursor movement:
- n+: move down n lines;
- n-: move n lines up;
- gg: move to start;

delete:
- dd: delete the current line;
- dG: delete all content after the cursor;

Page turning command:
- ctrl + f: turn down one page;
- ctrf + b: turn up one page;

Close the document:
x: save the current document and exit;
q: quit;
w: save the document;
q!: Exit VI/VIM without saving the file;

Replace source
Source list file location: /etc/apt/sources.list

5.1 Backup source list: cp /etc/apt/sources.list /etc/apt/sources.list.bak;
5.2 Open source file: sudo vim /etc/apt/sources.list;
5.3 Replace source file content (Ali source, you can continue to Baidu if you want others):

deb http://mirrors.aliyun.com/ubuntu/ jammy main restricted universe multiverse 
deb http://mirrors.aliyun.com/ubuntu/ jammy-security main restricted universe multiverse 
deb http://mirrors.aliyun.com/ubuntu/ jammy-updates main restricted universe multiverse 
deb http://mirrors.aliyun.com/ubuntu/ jammy-proposed main restricted universe multiverse 
deb http://mirrors.aliyun.com/ubuntu/ jammy-backports main restricted universe multiverse 
deb-src http://mirrors.aliyun.com/ubuntu/ jammy main restricted universe multiverse 
deb-src http://mirrors.aliyun.com/ubuntu/ jammy-security main restricted universe multiverse 
deb-src http://mirrors.aliyun.com/ubuntu/ jammy-updates main restricted universe multiverse 
deb-src http://mirrors.aliyun.com/ubuntu/ jammy-proposed main restricted universe multiverse 
deb-src http://mirrors.aliyun.com/ubuntu/ jammy-backports main restricted universe multiverse

5.4 Save and exit: esc :x
5.4 Refresh source path: sudo apt update;

Check the ip address:ifconfig
Reset role password:sudo passwd username
Root remote login:
8.1 Open the ssh configuration file sudo vi /etc/ssh/sshd_config
8.2 Comment PermitRootLogin without-passwordthis sentence (no matter if there is no);
8.3 Add PermitRootLogin yes;
The cd (change directory, modify directory) command uses:
- cd ~: Jump to the root directory of the current user;
- cd -: Jump back to the previous directory;
- cd: Equivalent tocd ~

The ls command uses:
- ls: view the files in the current directory
- ls <path>: View the files under the path <path>;
- ls -a: View all files (including hidden files) in the current directory, all files or folders .starting are hidden files;
- ls -l: List the detailed information of the file;
- ls -al: List detailed information of all files;
- ls -h: File information is displayed in KMGT format;

The meaning of each value in the detailed information of the file:

aliasAlias the command:
- alias: View all alias commands;
- alias la='ls -a': Give ls -athe command an alias name la, and the two commands have the same effect at this time;
  - Adding an alias to the command line is temporary. When the current terminal is closed, the alias will be gone; if you want it to be effective for a long time, you can modify the alias configuration file;
- unalias la: delete alias la;

Folder and file related commands:
- mkdir name: Create a folder namenamed ;
- mkdir /path1/path2/name -p: In the path2 folder under the path1 file, create a folder named name;
- rmdir name: remove a 空folder ;
- touch filename: Create a file, there can be multiple;
- cp test..txt /path/test.txt: Copy the test.txt file (folder) to the /path/ folder;
- cp test..txt /path/ttt.txt: Copy the test.txt file (folder) to the /path/ folder, and rename it to ttt.txt;
- mv test..txt /path/test.txt: Cut the test.txt file (folder) to the /path/ folder;
- rm -rf name: Used to delete the file (folder) named name
  - f: No prompt, no prompt if an error occurs;
  - r: Recursive delete;
- *.txt: fuzzy match a certain type of file-
  : rm -rf *.txtdelete all
vim configuration file:
- /etc/vimrc: The configuration set for all users, the configuration that all users can read;
- ~/vimrc: The configuration set for the current user, only the current user can read;
Linux configuration file:
- A file that will be executed every time the terminal is opened;
  - /etc/bashrc: Valid for all users;
  - ~/bashrc: Valid for the current user;
User management related instructions:
- useradd <username>: To create a new user, generally you need to specify -sthe parameter as /bin/bash;
- su <username>: switch user;
- passwd <username>: Set a password for the specified user;
- passwd: Set a password for the current user;
- userdel <username>: delete user;
  - -f: force delete;
  - -r: delete home directory at the same time;
- whoami: View the currently logged in user name;
- sudo: Execute commands with root authority;
  - You need to configure the user in /etc/sudoersthe file before you can use sudothe command;
  - visudo: Quickly open /etc/sudoersthe file and enter the editing state;
- vim /etc/passwd: View current system and user information of all users;

用户信息示例： root:x:0:0:root:/root:/bin/bash
解析： <用户名>:<用户密码:占位符>:<用户id>:<分组id>:<用户根目录位置>:<用户登录时执行的脚本>

- `vim /etc/shadow`: 系统所有用户密码文件；

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用户密码示例： sshd:*:19262:0:99999:7:::
解析： <用户名>:<用户密码>:<修改日期>:<密码不可修改的天数>:<密码需要修改的期限: 天>:<修改期限前N天发出警告>:<密码过期的宽限:天>
	- <用户密码> 详解：
		* 空表示密码为空， 不需要输入密码就可以登录；
		*  “*” 号表示账户锁定；
		*  “!” 号表示密码已过期；
		*  “$1$” 表明用 MD5加密；
		*  “$2$”  Blowfish 加密；
		*  “$5$” SHA-256 加密；
		*  “$6$” SHA-512 加密；

vim /etc/group: View all groups in the system;

实例： root:x:0:

15.1 Grouping:
- When creating a user, the system will automatically create a group with the same name as the user;
- groups: Check which group the current user is in;
- groups <username>: Check the group where the specified user is in;
- gpasswd -a <username> <group_name>: Add the specified user to the specified group Among them;
- gpasswd -d <username> <group_name>: delete and remove the specified user from the specified group;
- Group with rootpermission :
* ubuntu: sudo group | admin group | root group;
* centos: wheel group | root group;

File (folder) permission management chmod:
- parameter:
  - o: Other; chmod o+w <filename>: Add 'w' write permission to other users of the specified file;
  - u: owner; chmod u-w <filename>: remove 'w' write permission for specified file owner;
  - g: Belonging group; chmod g-r <filename>: Remove the 'r' read permission for the specified file's owning group (owner group);
  - a: all; chmod a+r <filename>: specified file, all users, add 'r' read permission;
    - Permission types and their corresponding values:
      - r: 4: readable;
      - w: 2: writable;
      - x: 1: ;
      - Example: sudo chmod 777 <filename>;
      - Example: sudo chmod u=777 <filename>;
      - Example: sudo chmod u=rwx <filename>;
Compression, decompression:
- zip <文件(夹)名> <压缩包名>: compressed files, folders;
- unzip <压缩包名>: unzip;
- tar

nginx-related:
- sudo apt install nginx: nginx install;
- sudo systemctl start nginx.server: Start nginx service;
- sudo systemctl stop nginx: Close the software;
- vim /etc/nginx/nginx.conf: nginx global configuration file;
Linux-based python environment management:

a. sudo pip3 install virtualenv virtualenvwrapper: Install python environment management tools;
b. ~/.bashrc: Edit (add) configuration files;
```
export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3.6 #指定新虚拟环境默认的Python版本
export WORKON_HOME=~/.envs#指定创建的新的虚拟环境保存在哪个文件夹下
source /usr/local/bin/virtualenvwrapper.sh#执行virtualenvwrapper.sh 脚本
```
c. mkvirtualenv test: Create a virtual environment testnamed and store it in WORKON_HOME=~/.envsthe configured ~/.envsfolder ;
d. workon test: Switch to testthe virtual environment;
e. deactivate: Exit the virtual environment;

|Pipeline:
convert the standard output of the previous statement into the standard input of the next statement;

Redirect:

>: write:

* 如果文件不存在，则新建文件；
* 如果文件存在， 则直接覆盖原文件；
`sudo ps -aux > pid.txt`: 将所有查询出来的进程结果， 写入pid.txt文件中；

>>addition:

`sudo ls ./ > pid.txt`: 将 `sudo ls ./ ` 执行的结果，追加到 `pid.txt` 文件中；

Classification:
- >Equivalent to 1>: standard output, the result of a correct execution;
- 2>: Error output, the result of executing an error;
- &>: all output: standard output + error output;

Command aliases:
- ln -s x fn1 fn2: fn1Give an alias name fn2, at this time is fn1completely equivalent to fn2;
Install the database (mysql 8.0):
sudo apt install mysql-server: After ubuntu 18.4, the system is not compatible with mysql5.7;

Mysql 8.0 login:
- sudo vim /etc/mysql/debian.cnf: Copy debian-sys-maintthe user 's password;
- mysql -u debian-sys-maint -p: Press Enter to enter the password;
- alter user 'root'@'localhost' identified with mysql_native_password by '123456': Modify rootthe user 's login password;
- Then you can use rootthe user to log in;

Ubuntu commands (updated all the time)

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