Linux Basic system permissions

Linux Base system Permissions file permissions

Linux, each file has three kinds of permissions

Permissions	impact on a file	impact on the directory
R (Read)	can read files	Catalog contents can be listed
W (write)	Can modify the contents of the file	Delete files can be created in the directory
X (Execute)	Can modify the contents of a file	Access to directory content

Note : The directory must have X permissions, or it will not be able to view its contents

UGO

Linux permissions are controlled based on the UGO model

• U on behalf of user, G for group, O on behalf of other
• Permissions for each file are set based on Ugo
• Permissions three a group (RWX), corresponding Ugo set separately
• Each file has an owner/user (user), the group that the users belong to (group), does not belong to the above is the other

Command Ls-ls to view information about files in the current directory

Here's a concrete example.

Permissions	Number of links	owned by	owning Group	File Size	Last Modified Time	name
-rwrw-r--	Number of links	Nothi	Nothi	4	26 20:59	Test
	Number of links is 1 (hard link)	Owned by Nothi	Owning Group is Nothi	Size is 4 bytes	Last modified on August 26	The file is called Test.

Where-rw-rw-r--the meaning is as follows

Owner Permissions	have group permissions	other people's rights
-rw	-rw	r--
Owner has read and write permissions	Members of the owning group have read and write permissions	Other people only read the permissions

Modify the properties of a file Chown

Chown the user file, modify the owner of the specified file to the specified user, such as Chown Nothi test.

-R parameter recursively modifies all the files in the directory for all users

Chgrp

The usage is similar to Chown

CHGRP group file, modify all groups of the specified file to the specified group, such as Chgrp Nothi test.

-R parameter recursively modifies the owning group of all files under the directory

Note : These two commands require root privileges

chmod

Modify the permissions of the file, the mode of the command is as follows: chmod mode file

General modification Methods

The format of the pattern is as follows

• U,g,o represents users, groups, and other
• A (All) represents all (Ugo)
• +,-, each delegate to join and delete the corresponding permission
• R, W, X for three kinds of permissions

pattern Example

Example	meaning
chmod u+x Test	Add execute permission to the owner
chmod g+r Test	Add Read permission to the owning group
chmod a+w Test	Add Write permission to a person

Digitally modified

Use digital 4,2,1 to represent R,W,X permissions respectively

When using numbers to represent permissions, each group of permissions corresponds to the sum of the numbers, for example, rw=4+2=6,rwx=4+2+1=7

To change the file test, the permission to Rwxrwxr-x, the command to chmod 775 test

Originally from: http://blog.csdn.net/nothi/article/details/10364643

Linux Basic system permissions