Linux basic command

Ao Yin 2021-04-08 10:33:11
linux basic command


One 、 Command format

Linux The basic format of the command in is as follows :

 command [ Options ] [ Parameters ]

notes : Some special commands do not follow this format

Two 、 system information

2.1、 Get the current user

who am i

2.2、 Get the current directory

pwd

2.3、 obtain IP Information

ip a|address

2.4、 Connect to remote address

ping domain name |IP

3、 ... and 、 Directory command

3.1、 List the contents

ls [-aldtr] [ Directory name ]
# By default, the directory name lists the current directory
# -a: List all the files and directories
# -l: List file and directory details
# -d: List only the directory itself
# -t: Sort by creation time
# -r: In reverse order
ll [-aldtr] [ Directory name ] # ls -l Abbreviated form , And ls Use consistent

3.2、 Toggle directory

cd [ route ]
# When the directory name is missing , Switch to the current user's home Under the table of contents

Special directory path :

Symbol route
. Current directory
.. Superior directory
/ System root
~ Current user's home Catalog
- Return to the last Directory

3.3、 Create directory

mkdir [-mp] Directory name
# -m: Specify permissions
# -p: Create multi-level directory

3.4、 Delete directory

rmdir Directory name
# Only empty directories can be deleted
rm [-rf] Resource name # Delete resources ( Directory or file )
# -r: Recursive delete
# -f: Don't ask

3.5、 Copy resources

cp [-rp] Source resource path Target resource path
# -r: Recursive replication
# -p: Copy with attributes , Instead of using default properties

3.6、 Move / Rename resource

mv The source of resources [ The target path ][ New resource name ]
# If the target path is not written , That is to rename ; If the new resource name is not written , Mobile ; If you write both , Move and rename

Four 、 File command

4.1、 create a file

touch file name [ file name ] [ file name ] [ file name ]...

4.2、 Edit the file

vi | vim file name # Enter view mode
i | a | o # Enter edit mode
# i: Start editing at the current cursor ;a: After the current cursor ;o: Start a new line under the cursor ;
ESC # Launch editing mode
: # Enter the bottom line command mode
wq! # Save and exit
q! # Exit without saving
# In view mode , Press down ZZ( Twice capitalized z), Save and exit quickly
4.2.1、 Show / Hide line numbers

In bottom line command mode , Input set nu/nonu enter , You can show or hide line numbers

4.2.2、 Jump to a line

In bottom line command mode , Input to n enter , Can jump to n That's ok

4.2.3、 Find content

In view mode , Input /xxx You can find... In the file xxx Content , Press n Find the next one ; Press N Find the last one

5、 see file

5.1、 Check all
cat file name # Start with the first line to see the contents of the file , Show it all
tac file name # View the contents of the file from the last line , Show it all
nl file name # Start with the first line to see the contents of the file , Show it all , And display the line number
5.2、 View by page
5.2.1、more

similar cat , But it will be displayed page by page , More convenient for users to read page by page , And the most basic command is to press the blank key (space) The next page shows , Press b The key will go back (back) One page shows

more file name

Common operation command

  • Enter Down n That's ok , Need to define . The default is 1 That's ok
  • Ctrl+f Scroll down one screen
  • Space bar Scroll down one screen
  • Ctrl+b Scroll up one screen
  • b Scroll up one screen
  • = Output the line number of the current line
  • :f Output filename and line number of current line
  • v call vi Editor
  • ! command call Shell, And execute the command
  • q sign out more
5.2.2、less

And more similar ,less You can browse files at will , Support page turning and search , Supports page up and page down .

less file name

Common operation command

  • / character string : Search down " character string " The function of
  • ? character string : Search up " character string " The function of
  • n: Repeat the previous search ( And / or ? of )
  • N: Repeat the previous search in reverse ( And / or ? of )
  • b Page up
  • d Turn back half a page
  • h Show help screen
  • q sign out less command
  • u Scroll forward half a page
  • y Roll a line forward
  • Space bar Scroll one page
  • Enter key Roll a line
  • G Jump to the last line
  • [pagedown]: Page down
  • [pageup]: Page up
5.3、 View by line
5.3.1、head

head Command can be used to view the contents of the beginning of a file , There is a common parameter -n Used to display the number of rows , The default is 10, It shows 10 The content of the line .

head [-qvcn] file name
# -q: Hide filename ( Default )
# -v: Show filename
# -c: How many characters are displayed
# -n: How many lines are displayed

5.3.2、tail

tail The command can be used to view the contents of a file , There is a common parameter -f Often used to look up log files that are changing .

tail -f filename Will be able to filename The last part of the file is shown on the screen , And keep refreshing , as long as filename Update to see the latest file content .

tail [-fqvcn] file name
# -f: Cyclic reading , Read out every time new content is added
# -q: Do not display processing information
# -v: Display processing information
# -c < number >: Number of characters read
# -n < number >: Number of rows read

5、 ... and 、 Pack command

Linux The commonly used compression package format in is :.tar.tar.gz.gz Of , But it also supports .zip and .rar Format .

5.1、tar type

5.1.1、 Compress
tar [-cvzf] Compressed file name Target resource name [-C Pathname ]
# -c or --create: New compressed file
# -v: Display during execution of instructions
# -z or --gzip or --ungzip: adopt gzip Instruction processing backup file .
# -f < Compressed file name > or --file=< Compressed file name >: Specify the compressed file . Be careful , This option must be at the end of the option

5.1.2、 decompression
tar [-xvzf] Compressed file name [-C Pathname ]
# -x or --extract or --get: Unzip the compressed file

5.1.3、 View compressed files
tar [-tvzf] Compressed file name
# -t or --list: List the contents of the compressed file .

5.2、zip type

Linux This is not supported by default zip, So you need to install zip and unzip Software .

The installation command is as follows :

yum -y install zip
yum -y install unzip

5.2.1、 Compress
zip [-qr] Compressed file name [ Target resources ] [ Target resources ] ...
# -q: Do not show instruction execution
# -r: Recursive processing , Process all files and subdirectories in the specified directory

5.2.2、 decompression
unzip [-lnv] Compressed file name
# -l: Display the files contained in the compressed file
# -n: When decompressing , Don't override the original file
# -v: Look at the contents of the compressed file , Do not decompress

5.2.3、gzip command

gzip Is a command that can be compressed or decompressed , After it compresses the file , The name will be followed by ".gz" Extension .

gzip [-drl] Resource name | Compressed file name
# -d: decompression
# -r: Recursive processing
# -l: List information about compressed files

6、 ... and 、 User command

Linux The system is a multi-user and multi task time-sharing operating system , Any user who wants to use system resources , You must first apply to the system administrator for an account , Then enter the system as this account .

On the one hand, the user's account can help the system administrator to track the users who use the system , And control their access to system resources ; On the other hand, it can help users organize files , And provide security protection for users .

Each user account has a unique user name and password .

After the user enters the correct user name and password at login , You can access the system and your home directory .

6.1、 Create user

useradd [-dgG] user name
# -d: Specify the user's home directory , If not specified , It's in /home Create a folder with the same user name as the home directory
# -g: Specifies the user's membership group
# -G: Specify the user's satellite group

6.2、 Set the password

passwd [-dlu] user name
# -d: Delete password
# -l: Lock account , Make it unavailable
# -u: Unlock the account , Make it available

6.3、 Switching users

su user name

explain :

[root@192 ~]# :root The user is in 192 Sign in , The current in the ~ Under the table of contents ,# On behalf of Super Administrator .

[silence@192 root]$ :silence The user is in 192 Sign in , The current in the root Under the table of contents ,$ On behalf of ordinary users .

6.4、 Modify the user

usermod [-degGlLuU] user name
# -d < Log in to the directory >: Modify the directory when the user logs in
# -e < Term of validity >: Modify the validity period of the account
# -f < Buffer days >: Modify how many days after the password expires to close the account
# -g < group >: Modify the user's group
# -G < group >: Modify the additional group to which the user belongs
# -l < Account name >: Change user account name
# -L: Lock user password , Invalidate password
# -u <uid>: Modify the user ID.
# -U: Unlock password .

6.5、 Delete user

userdel [-r] user name
# -r: Delete the user's home directory

7、 ... and 、 User group command

Each user has a user group , The system can centrally manage all users in a user group . Different Linux The system has different rules for user groups , Such as Linux The following user belongs to a group of users with the same name , This user group is created at the same time as the user is created .

7.1、 Create user group

groupadd [-g gid] Group name
# -g gid: Specified group id

groupadd The command is used to create a new workgroup , Information about the new workgroup will be added to the system file .

Related documents :

  • /etc/group Group account information .
  • /etc/gshadow Security group account information .
  • /etc/login.defs Shadow Password Suite configuration .

7.2、 Modify user groups

groupmod [-n gname] Group name
# -n: Modify user group name

7.3、 Delete user group

groupdel Group name

8、 ... and 、 File permissions

Reference resources :

https://www.runoob.com/linux/linux-file-attr-permission.html

Linux The system is a typical multi-user system , Different users are in different positions , Have different permissions .

In order to protect the safety of the system ,Linux The system accesses the same file for different users ( Including catalog files ) There are different rules for the authority of .

stay Linux We can use ll perhaps ls –l Command to display the properties of a file and the users and groups to which the file belongs .

stay Linux The first character in represents that the file is a directory 、 Files or linked files, etc .

  • When it comes to d It's a directory
  • When it comes to - File ;
  • if l Is represented as a linked document (link file);
  • if b It means the interface equipment available for storage in the device document ( Random access device );
  • if c Is the serial port device in the device file , For example, keyboard 、 mouse ( Disposable reading device ).

In the next characters , In groups of three , And they are rwx The combination of three parameters of . among , r Representative readable (read)、 w Representative may write (write)、 x Representative executable (execute). It should be noted that , The location of these three permissions will not change , If you don't have permission , There will be a minus sign - nothing more .

The properties of each file are shown in the first section on the left 10 Characters to determine :

Use from left to right 0-9 These numbers represent .

The first 0 Bit to determine the file type , The first 1-3 The position is the owner ( The owner of the document ) Have permission to this file . The first 4-6 The genus group is determined by the position ( The same group of users of the owner ) Have permission to this file , The first 7-9 Determine that other users have permissions for this file .

about root Users , In general , The file's permissions don't work for it .

8.1、 Modify file belongs to group

chgrp [-R] Group name file name
# -R: Recursive modification

8.2、 Modify file owner

The generic group can be modified at the same time

chown [-R] user name [: Group name ] file name

8.3、 Modify file permissions

chmod [-R] xyz file name

Linux There are two ways to set file properties , One is numbers , One is the symbol .

Linux There are nine basic permissions for a file , Namely owner/group/others( The owner / Group / other ) Each of the three identities has its own read/write/execute jurisdiction .

Let's review the data just mentioned above : The permission character of the file is : -rwxrwxrwx , The nine permissions are in groups of three ! among , We can use numbers to represent each authority , The score comparison table of each authority is as follows :

  • r:4
  • w:2
  • x:1

Each identity (owner/group/others) Three rights of each (r/w/x) Scores need to be accumulated , For example, when the permission is : -rwxrwx--- The score is :

  • owner = rwx = 4+2+1 = 7
  • group = rwx = 4+2+1 = 7
  • others= --- = 0+0+0 = 0

Options and parameters :

  • xyz : This is the permission attribute of the number type just mentioned , by rwx The addition of attribute values .
  • -R : Recursion (recursive) Continuous change of , That is to say, all files in the subdirectory will be changed

Nine 、 Process command

9.1、 Check the process

ps -ef | grep Process keywords

View the firewall process ID:

9.2、 Close the process

kill [- Semaphore ] pid
# Common semaphores :1 (HUP): Reload process .9 (KILL): Kill a process .15 (TERM): Normally stop a process .

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本文为[Ao Yin]所创,转载请带上原文链接,感谢
https://javamana.com/2021/04/20210408101957651r.html

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