What are the basic operations of Linux?

Basic Linux operations include: 1. [passwd] is to set a password; 2. [su] is to switch users; 3. [who] is to view online users; 4. [whoami] is to view the current user User; 5. [hostname] displays the host name, etc.

The basic operations of Linux are:

1. Overview

1. Common operating systems

Server operating systems: linux, unix, windows server

Stand-alone operating systems: windows (dos, ucdos, win95, win98, win2000, XP, Vista, Win7, Win8)

Mac, Linux (Ubuntu)

mobile operating system Android, iOS, Windows Phone

# 2, Linux operating system introduction introduction

Linux is a free and open source UNIX-like operating system. It has openness, multi-user, multi-tasking, rich network functions, reliable system security, and good portability. Good user interface (command interface, graphical interface, etc.), excellent speed performance and other advantages. Now it is mainly used for:

• Most servers use linux, and JEE is deployed to the server

• Some companies and schools use linux for R&D and Teaching

• Many embedded development uses linux

• Cloud computing and big data are cluster networks linux: centos

Linux is composed of:

• linux kernel (managed by linus team)

• shell: the interface for users to interact with the kernel

• File system: ext3, ext4, etc. windows have fat32, ntfs

• Third-party application software

Linux The operating system version consists of a kernel version (managed by the linus team) and a release version (some software companies use the kernel as the basis, and then add some software and documents to form a release version). Common release versions are:

- red hat ： rhel, centos

- debian ： debian, ubuntu (desktop)

- android

2. Linux system environment

By default, there are 6 command interaction channels and a graphical interface interaction channel. The graphical interface channel is entered by default:

• Command interaction mode switching: ctrl alt f1---f6

• Graphic interactive interface ctrl alt f7

1. Graphical interface interaction mode

• terminal: The command terminal of the graphical interface, which is an extension of the graphical interface interaction channel and depends on the graphical interface

2. Command interaction mode

• Command prompt:

  shen@ubuntu:~$

• shen: Username

• ubuntu: Host name

• ~ : Path, if the current If the path is exactly the root directory where the user stores data, it will display ~

• $: Type of user $ represents ordinary user # represents super User

3. Commonly used commands

(press tab to create automatic completion)

1. Log out, Shut down and restart

• Logout: logout or exit

• Shutdown: shutdown - h Time

h: Shut down

Time:

1. now: Immediately

2. 12.30: Specify the specific time

3. 3: A few minutes later

Note: Not every user can complete the shutdown. A super user or authorized user is required to execute this command. Ordinary users must The super user configuration sudo command can perform the shutdown operation (the permissions are placed here/etc/sudoers). When an ordinary user is authorized, the operation can be completed through [sudo shutdown -h now]. sudo means using the super user permissions (given ) to execute a command, similar to running as administrator in window

Restart:

shutdown -rTime (permission issues are similar to the above)

2. System command

##passwd: Set password
The default root account of ubuntu is not enabled. As long as Set the root password to open [sudo passwd root]

su: Switch users
For example, su root, the root user will not switch to other accounts. Password required

sudo apt-get update

Update system

who and whoami

• ##where

who
• : View online users

• whoami : View the current user, such as

Which window tty2 represents (ctrl alt f2), pts/1 represents the terminal opened in the graphical interface.

• hostname: Display host name

• ##uname: Display system information

    -

  a : Display complete system information

• top: Display information on the current time-consuming process (part), every 3 Refresh once every second, similar to Windows Task Manager (cltr c interrupt)

• ps : Display a snapshot of the current process (all)

  - axu

• df ：Disk usage (disk free)

• ifconfig ：View or Configure the network card information, such as ipconfig of windows

• ping Test the connection with the target host

For example, test the connection between the local machine and the target host The connection situation in the virtual machine, (local IP: 169.254.64.182, virtual machine IP: 172.25.0.95), in the virtual machine terminal, test

ping 169.254.64.182 [Press Ctrl c to end], in Ping 172.25.0.95

• netstat in this machine (cmd): Network connection details

• clear : Clear the screen (windows: cls)

• man: Help command

You can view the parameters of the command , such as man ls

• kill: kill process (kill pid)

• useradd : Add user

First check the user information, the command is sudo cat /etc/passwd, introduce one of the user information

 hadoop:x:1000:1000:UbuntuA,,,:/home/hadoop:/bin/bash

-

hadoop:Username

-

x: Password: Already encrypted, the password is stored in /etc/shadow

-

1000: Account id, userId

-

1000: Group id, group id

-

UbuntuA,,,: Account description

-

/ home/hadoop: The default location where the account stores files ~

-

/bin/bash: The user’s shell script parsing method, sh, bash, rbash

Then create a user (take creating the "lijing" user as an example), the steps are as follows:

1. Create the

/home/lijing directory (create the "lijing" file under home )

2. Execute the

useradd command

-d: Specify the home of the user Path

- s: The user’s shell parsing method

3. Use

passwd to set the password

4 .

suSwitch user

Related learning recommendations:

linux video tutorial

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