Permission control under Linux system

Permission control under Linux system

1. file Permissions

in our Linux system , the permissions of a file or directory can be divided into 3 types :

R:4 Read

W:2 Write

X:1 Execution

Example :

644: (4+2) (4) (4)

First 6: The permissions of the owner of the current file , 6=4+2 readable writable permissions

Second 4: represents the group permission that the current file belongs to, 4=4 read -only permission

Third 4: represents the current file's out-of-group permissions , 4=4 readable permissions

2. commands to view file permissions:(ls-l or LL)

The total can be divided into 7 major columns :

column 1 ( divided into ten columns ):

1: type of File ,- represents a normal file , D represents a directory , and L represents a soft connection ( equivalent to Shortcut to Window System )

Analyze Permissions with file Bigmovie.avi file

2-4: Current file owner's permissions (rw-), read writable permission ,- symbol indicates no corresponding permission

5-7: The owning group permission (r--) of the current file , readable permission

8-10: out-of-group permissions (r--) for the current file, readable permissions

column 2 : number of nodes in a file (node)

column 3 : Indicates the file owner root user

column 4 : the group root user group that represents the file belongs to

column 5 : shows the size of the file , the default is byte byte , You can use the command LS-LH more user-friendly view of file size

column 6 : Last modified time of file

Column 7 : Name of the file or directory

1. user groups and users in Linux1. Introduction

in our Linux system , There are many user groups , You can also create user groups manually , There are a lot of users under different groups of users .

2. Create a user group and related commands

Groupadd Phpzu: Create a php Group

GROUPADD-G 501 Javazu: Create a group name Javazu, group ID 501 ( Note : System Group ID are less than , Custom Groups ID are greater than ( inclusive ))

Groupdel Phpzu: Delete Group named Phpzu

Groupmod-n New group name old group name

Groupmod-g New group ID old group name

① Creating a user group

column 1 : Group name

column 2 : Group Password

column 3 : group ID

column 4 : users within a group

② Deleting a user group

③ Modifying user groups

Permission control under Linux system