Ubuntu operations refer to north

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Ubuntu official Website

Introduction to the

Linux is a free and open source UniX-like operating system that uses the Linux kernel. Generally, Linux is packaged as a Linux distribution for desktop computers and servers. Ubuntu is one of the Linux distributions. The popular Linux distributions are: Ubuntu, RedHat, CentOS, Debian, etc.

Remote control management

XShell is a powerful security terminal simulation software, it supports SSH1, SSH2. It can be used to access remote servers in different systems on the Windows interface, thus achieving the purpose of remote control terminal

XFtp: is a powerful SFTP, FTP file transfer software. With XFtp, Windows users can securely transfer files between UNIX/Linux and Windows PCS

XShell and XFtp school home free version of the official website download

The directory structure

directory	instructions
bin	Store binary executable files (ls,cat,mkdir, etc.)
boot	Stores the various files used for system boot
dev	Used to store device files
etc	Saves the system configuration file
home	The root directory for storing all user files
lib	Stores shared libraries and kernel modules needed to run programs in the file system
mnt	The installation point at which the system administrator installs the temporary file system
opt	Placement of optional application packages for additional installations
proc	A virtual file system that stores the current memory mapping
root	Superuser directory
sbin	Stores binary executable files, which can only be accessed by root
tmp	Used to store various temporary files
usr	Important directory /usr/local Local administrator software installation directory
var	A file used to hold data that needs to be changed at run time

The editor

vim

Enter insert mode: In Edit mode, enteriEnter insert mode and insert text information
Enter command mode: In edit mode, press firstESCAnd then type:Enter command mode

Common commands are as follows:

:q Exit directly
:wq Save and exit (you can create a new file if no file exists)
:q! Forced out of
:set paste Paste format
:w file Saves the current content to a file
:set number Indicates the line number displayed in the edit file
:set nonumber does not display line numbers in the edit file

nano

Nano is a character terminal text editor, a bit like the EDITOR program under DOS. It is much simpler than vi/ Vim and is more suitable for Linux beginners. The nano is the default editor for some Linux distributions.

The command is as follows:

ctrl + o: save
ctrl + wSearch:
ctrl + y: back
ctrl + v: the next page
ctrl + x: quit

Software Package Management

Advanced Packaging Tool (APT) is a software package management program in Debian/Ubuntu Linux system. It can be used to find the desired software package, and it is easy to install, uninstall and update. It can also be used to upgrade Ubuntu; The source file of APT is sources.list in /etc/apt/.

Modifying a data source

Due to the problem of domestic network environment, we need to change the data source of Ubuntu to domestic data source. The procedure is as follows:

Viewing the System Version

$ lsb_release -a
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The output

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04 LTS
Release:	16.04
Codename:	xenial
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Codename is Xenial, which is the name of our Ubuntu system and is needed to modify the data source

Edit data source

$ vi /etc/apt/sources.list
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Delete all contents and change to

deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted  universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverseCopy the code

Update data source
```
$ apt-get update
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```

User management

The Linux operating system is a multi-user operating system that allows multiple users to log on to the system and use resources at the same time. The system will distinguish each user’s files, processes, tasks and work environment according to the account, so that each user can work without interference.

Using the Root user

In the actual production operation, we basically use the super administrator account to operate the Linux system, that is, the Root user. By default, the Root account is disabled in The Linux system. We need to set an initial password for the Root user to facilitate our use.

Set the password of user Root
```
$ sudo passwd root
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```
Switch to user root
```
$ su
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```

Example To enable remote login to the Root user

Example Modify the sshd_config configuration file

$ vi /etc/ssh/sshd_config
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Modify the following configurations

#PermitRootLogin Without -password // Comment this linePermitRootLogin YES // Join this lineCopy the code

Restart the service

$ service ssh restart
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Common Commands

File directory Command

The command	instructions	parameter	Parameters that
ls	Displays a list of files and directories	-l	Lists the details of the file
		-a	Lists all files in the current directory, including hidden files
mkdir	Create a directory	-p	If the parent directory does not exist, the parent directory is the parent directory
cd	Switch directory
touch	Generate an empty file
echo	Generate a file with content
cat	Display text file contents
cp	Copy files or directories
rm	Delete the file	-r	Delete the directory
		-f	Mandatory delete
find	Finds the specified file in the file system	-name	The file name
grep	Finds the specified string in the specified text file
tree	Use to list the contents of a directory in a tree
pwd	Displays the current working directory
ln	Establishing a soft connection
more	Displays the contents of a text file in pages
head	Displays the beginning of the file
tail	Displays the contents at the end of the file	-f	Track real-time output

APT command

Installing Software Packages

$ apt-get install packagename
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Deleting a Software Package

$ apt-get remove packagename
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Updating the Software Package List

$ apt-get update
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Upgrade to the latest system (with caution)

$ apt-get upgrade
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Decompression command

The compressed file

$ tar -zcvf test.tar.gz test\
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Unzip the files

$ tar -zxvf test.tar.gz
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System Management Commands

The command	instructions
start	Displays more information about a specified file than the ls command
who	The online login users are displayed
hostname	Display host name
uname	Displaying system Information
top	Displays the processes that consume the most resources in the current system
ps	Displays transient process status
du	Displays the total disk space used by the specified file (directory)
df	The file system disk space usage is displayed
free	Displays the current memory and swap space usage
ifconfig	Display network interface information
ping	Test the network connectivity
netstat	Display network status information
clear	Clear the screen
kill	Kill a process

User Management Commands

The command	instructions
useradd	Add user
usermod	Modify the user
userdel	Delete user

Shutdown restart

Immediately shut down

$ shutdown -h now
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Immediately restart

$ reboot
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File directory Permissions

View permissions on files and directories

Ls -al: The ls command displays only the file name without parameters. The ls -al command displays the permission information about files or directories

Ls -l: Displays the following information: file type, file permission, file user, file owning group, file size, file creation time, and file name

Such as:

-rw-r--r-- 1 antoniopeng antoniopeng 675 Oct 26 17:20 .file_name
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The parse of the preceding command is as follows:

-rw-r–r–	1	antoniopeng	antoniopeng	675	Oct 26 17:20	.file_name
Document types and permissions	The number of connections	User of the document	Document Group	Document size	Date the document was last modified	The document name

-rw-r--r--
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The first character represents the document type, and the remaining characters represent permissions

-: Common file
rw-: Indicates that antoniopeng has read and write permissions but does not have run permissions
r--: indicates that the user group Antoniopeng has read permissions but does not have write and run permissions
r--: Other users have read permissions but do not have write or run permissions

All document types

dSaid directory
lIndicates soft connection
-Represents a common file
cRepresents a serial port character device file
bRepresents a block device file available for storage

All permissions

r: read only
w: can write
x: executable

Changing operation Permissions

chown

Changes the owner of a file or directory. The owner includes users and user groups

$Chown [-r] User name file or directory
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$Chown [-r] User name User group name File or directory
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-r: Recursively changes permissions to update the permissions of all files and subdirectories in the directory

chmod

Change the access permission

$Chmod [who] [+ | | =] [mode] file name
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Who indicates that the operation object can be one or a combination of the following letters:

uUser: user
g: user group group
o: indicates another user
a: indicates that all users are default

+ / – / = Indicates the operation permission:

+: indicates adding a permission
-: cancels a permission
=: Grants the given permission to revoke all previous permissions on the document

Mode:

r: read only
w: can write
x: executable

Permission number setting method

0: no permission, 1: executable permission = x, 2: write permission = w, 4: read permission = r.