Change file read/write permissions chmod, owner, or group under Linux Chown

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In the terminal input:
Ls-l xxx.xxx (xxx.xxx is file name)
Then there will be similar messages, mostly these:
-rw-rw-r--
The following figure:

A total of 10 digits
Where: The front one-represents the type, if it is a directory, the front one is D
The middle one of the three rw-represents the owner (user)
Then the three rw-represent groups (group)
The last three r--represent other people (other)
And then I'll explain the 9 digits in the back:
R indicates that the file can be read (read)
W indicates that the file can be written (write)
x indicates that the file can be executed (if it is a program)
-Indicates that the appropriate permissions have not been granted
Now it's time to talk about modifying file permissions:
In the terminal input:
chmod o+w xxx.xxx
To give other people permission to write xxx.xxx this file
chmod GO-RW xxx.xxx
Indicates deletion of Read and write permissions for groups and other people in xxx.xxx
which
U on behalf of owner (user)
G represents the group in which the owner is located
O on behalf of others, but not u and g (Other)
A represents all the people, including U,g and O.
R indicates that the file can be read (read)
W indicates that the file can be written (write)
x indicates that the file can be executed (if it is a program)
Where: Rwx can also use numbers to replace
R------------4
W------------2
X------------1
-------------0
Let's go:
+ Indicates adding permissions
-Indicates delete permission
= means to make it a unique permission
When everyone is aware of the above, then some of our common permissions are easy to understand:
-RW-------(600) Only the owner has read and write permission
-rw-r--r--(644) Only the owner has read and write permission, the group and others only Read permission
-RWX------(700) Only the owner has access to read, write, execute
-rwxr-xr-x (755) Only the owner has the right to read, write, execute, group and others only read and execute
-rwx--x--x (711) Only the owner has permission to read, write, execute, group and others only execute
-rw-rw-rw-(666) Everyone has access to read and write
-RWXRWXRWX (777) Everyone has access to read and write and execute
Equivalent wording:
chmod u+rw xxx.xxx = chmod xxx.xxx
chmod a+r xxx.xxx = chmod 444 xxx.xxx
If you want to add special permissions, you must use a 4-digit number to represent it. The corresponding values for special permissions are:
s or S (SUID): corresponds to a value of 4.
s or S (SGID): corresponds to a value of 2.
T or T: corresponds to the value 1.
Modifying file permissions in the same way is OK.
chmod 7600 xxx.xxx
To modify the permissions for all files in a directory at once, including file permissions in subdirectories, use the parameter-R representation to initiate recursive processing.
For example:
chmod 777/home/user Note: Only the permissions for the/home/user directory are set to RWXRWXRWX
Chmod-r 777/home/user Note: The permissions for the entire/home/user directory and the files and subdirectories in it are set to rwxrwxrwx

Use command Chown to change the ownership of a directory or file
Files and directories can not only change permissions, their ownership and user groups can also be modified, and set permissions similar to the user can be set through the graphical interface, or the implementation of the Chown command to modify.
Chown User Xxx.xxx
To change the group you belong to, use the following command:
Chown:users xxx.xxx
To change the owning users and groups at the same time:
Chown User:usergroup xxx.xxx
To modify permissions for the directory and subdirectories, use the-r argument, as in the previous procedure.