The article directories

• 1. Basic introduction to permissions
• 2. RWX permission details
• • 2.1 RWX applies to files
  • 2.2 RWX Applies to directories
• 3. Actual cases of file and directory permissions
• • 3.1 The following information is displayed in LS -L:
• 4. Change the permission by chmod
• • 4.1 Basic Description:
  • 4.2 Method 1: +, -, = Change permission
  • 4.3 Second Method: Change permission digitally
• 5. Change the file owner to chown
• • 5.1 Basic Introduction
• 6. Change the file/directory group -chgrp
• • 6.1 Basic Introduction
  • 6.2 Case Demonstration
  • 6.3 Best Practices – Police and Bandit games
  • 6.4 Exercise 1 after class
  • 6.5 Exercise 2 after Class

1. Basic introduction to permissions

• ls -lIs displayed as follows:

-rwxrw-r-- 1 root root 1213 Feb 2 09:39 abc
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• 0-9A description

1. The first0Bits determine the file type (d, - , l , c , b)
   
   lIt’s a link, the equivalent of a Shortcut on Windows
   
   dIs a directory, the equivalent of a Windows folder
   
   cIt’s character device file, mouse, keyboard
   
   bIt’s a device, like a hard disk
2. The first1-3Bits determine that the owner (the owner of the file) has permissions on the file. –User
3. The first4 to 6Bit to determine the permission of the owning group (the same user group) to the file, –Group
4. The first7-9Bits to determine whether other users have permissions on the file —Other

2. RWX permission details

2.1 RWX applies to files

1. [ r ]Stands for read: can be read, viewed
2. [ w ]Indicates Write: a file can be modified but cannot be deleted. To delete a file, you must have the write permission for the directory in which the file resides.
3. [ x ]Execute: indicates that the command can be executed

2.2 RWX Applies to directories

3. Actual cases of file and directory permissions

3.1 The following information is displayed in LS -L:

-rwxrw-r-- 1 root root 1213 Feb 2 09:39 ab
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1Files: number of hard connections or directories: number of subdirectories root user Root group1213File size (bytes), if folder, displayed4096Bytes in Feb2 09:39Last modified date ABC file nameCopy the code

4. Change the permission by chmod

4.1 Basic Description:

4.2 Method 1: +, -, = Change permission

• u: Owner,g: All groups,o: Others,a: All (U, G, OThe sum total of)

1. Chmod u= RWX,g=rx,o=x Name of the file or directory
2. Chmod o+w Specifies the name of the file or directory
3. Chmod a-x Specifies the name of the file or directory

• Case presentation

1. toabcThe owner of a file has read and write permissions for the file group and other groups.

chmod u=rwx,g=rx,o=rx abc
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2. toabcThe owner of a file can add the group write permission to the file

chmod u-x,g+w abc
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3. toabcAdd the read permission to all users of the file

chmod a+r abc
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4.3 Second Method: Change permission digitally

r=4 w=2 x=1 rwx=4+2+1=7
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chmod 755 /home/abc.t
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5. Change the file owner to chown

5.1 Basic Introduction

Chown newOwner Changes the owner of a file/directoryCopy the code

Chown newowner:newgroup Changes the owner and group of a file or directoryCopy the code

chown tom /home/abc.txt
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chown -R tom /home/test
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6. Change the file/directory group -chgrp

6.1 Basic Introduction

CHGRP newgroup file/directoryCopy the code

6.2 Case Demonstration

1. Please send/home/abc.txtThe file group is changed toshaolin(shaolin)

groupadd shaolin
chgrp shaolin /home/abc.txt
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2. Please send/home/testAll files and directories in the directory are changed toshaolin(shaolin)

chgrp -R shaolin /home/test
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6.3 Best Practices – Police and Bandit games

Police, bandit Jack, Jerry, xh, XQCopy the code

useradd -g police jack ; useradd -g police jerry
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useradd -g bandit xh; useradd -g bandit xq
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chmod o=r,g=r jack.txt
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6.4 Exercise 1 after class

• Practice file permission management. Complete the following steps.

1. Create two groups (SX, YG)
2. Create four users (Tang Seng, Wukong, Bajie, Sha Seng)
3. Set the password
4. Put Wukong, Eight quit into the monster Tang Seng sand Seng in the immortal
5. Create a file with monkey. Java to output I am monkey.
6. Give Bajie a permission to r w
7. Monkey. Java (I am pig)
8. Tang Seng Sha Seng has no authority on this file
9. Put Sand monk in the monster group
10. Ask the sand monk to modify the file monkey and add a sentence (” I am sand monk, I am monster!” );
11. Discuss and test the details of folder RWX!! X: indicates that you can access the directory, for example, CD. R: indicates that you can ls and display the contents of the directory. W: indicates that you can delete or create files in the directory
12. Schematic diagram
    
    

6.5 Exercise 2 after Class