Linux System user and group management

User and Group Management

Linux is a multi-user multi-tasking network operating system, as a network administrator, it is essential to master the creation and management of user groups.

Learning Essentials:

• Understand the profiles of users and groups of the group.
• Familiar with the creation and maintenance management of Linux users.
• Familiar with the creation and maintenance management of Linux under the cluster.
• Be familiar with how User Manager is used.

First, the user account (user) under the Linux system mainly consists of 3 kinds of

1. Super User (Admin User: root)
2. Normal User (login user, login account): Created by the system administrator, can log on to the Linux system, but only the files within their own directory, limited permissions.
3. System User: Mainly used for applications, support maintenance system operation, but the system running indispensable users, such as: bin,daemon,adm,ftp and Mail and other user accounts, are built-in users of Linux system (generally do not consider).

#su命令

Function: Transition to another user.

Format: su [-] User name

Note: When you do not specify a user name, you convert to root, and when you specify the-option, the environment is also transformed. When an ordinary user executes Su, it is necessary to enter the user name of the user to be converted.

* New User *

#useradd user1

Function: Create a new user home directory with the same user name by default

#useradd-D/home/xf user1

Function: Specify the user's home directory

#useradd-S/bin/false user1

Function: User Login-"shell program:/bin/bash, if do not want this user to log in, can modify the shell program is:/bin/false, this with the user even if the login can not execute the linux command.

#useradd-G user User1

Function: Specify a group that already exists for the user

#useradd-G user User1

Function: Let the user belong to another group again

Table 1-1

Table 1-2

Modify User

#usermod option User Name

-D: Modify the user's home directory #usermod-D/ljj/user1 user1

-L: Modify the user's account name #usermod-L USER11 user1

-G: Change the user's base group

-G: Change the user's additional group #usermod-G group1 user1

-C: Modify note information

-E: Modify the expiration date of the account

-S: Modify the shell used when logging in

-L: Lock user password

-u: Unlock user password

Delete User

#userdel-R user1

Features: delete users and delete their home directories

Group of Accounts (group)

A group is a collection of users who can share files and other system resources;

The principle of grouping is divided by working relation or user nature;

The correspondence between users and groups is many-to-many, and a group can contain multiple users, with the same group permissions as the group users.

Table 2-1

New User Group

#groupadd Group Name

#groupadd group1

#groupadd group2

#groupadd Group3

#groupadd GROUP4

#groupadd-G GID (group number) Gname (group name)

#groupadd-G 530 group2

Features: New user group

Ways to add users to a group

1. Specify the GID for this group when creating a new user
2. Modify the group properties of an existing user with the Usermod command
3. Modify the passwd and group files directly.
4. #gpasswd-a group1 user1

Delete a user group

#groupdel user Groups

#groupdel group2

Linux System user and group management