Linux User Management-user account management, linux User Management

Linux User Management-user account management, linux User Management

1. add, delete, modify, and query user accounts

1> Add User ------ useradd

Note: 1. the user name should not be a pure number or start with a number.

2. Change the logon shell to/sbin/nologin to disable user logon.

Format: useradd [Option] User Name

Common Command Options

-U: sets the UID mark number.

-D: Specifies the user's home directory. The default value is/home/'username'

-G: Specifies the user's basic group.

-G: Specify the user's additional group.

-E: Specifies the user's expiration time.

-M: Do not create and initialize the home directory for the user

-S: Specifies the user's logon shell

Exercise:

 

1) create an account stu01 and set the home directory to/opt/stu01.

[Root @ stu ~] # Useradd-d/opt/stu01 stu01

 

2) create an account stu02 with the uid of 10001. The account expired on November 30,. Set the basic group to stu01.

 

[Root @ stu ~] # Useradd-u 10001-e-g stu01 stu02

[Root @ stu ~] # Id stu02
Uid = 10001 (stu02) gid = 502 (stu01) groups = 502 (stu01)

　　Command: id username --- view user information

2> set password ------ passwd

Format: passwd [Option] User Name

Note: 1. the root user can change the password of any user.

2. All users can change their passwords.

Common Command Options

-D clear the user's password so that the user can log on without the password

-L locking the user account means that the user cannot log on. [add two exclamation points before the corresponding password string in shadow !!]

-S: Check whether the user account is locked

Stu01 LK 0 99999 7-1 (Password locked.) [Account locked]

Stu01 PS 0 99999 7-1 (Password set, MD5 crypt.) [Account unlocked]

-U: Unlock the user account. [clear the two exclamation points added before the timed password string]

-- Stdin obtains the password from the standard input

Exercise:

1) set the password to redhat from standard input to stu01 for stu01 operations

[Root @ stu ~] # Echo 'redhat' | passwd -- stdin stu01

 

3> modify existing user ------ usermod

Format: usermod [Option] User Name

Common options

-L change the user's login name

-L lock the user account [add an exclamation point before the password string in shadow !]

-U unlock user account [exclamation point added upon unlocking]

-U-d-e-g-G-s and useradd commands are the same

4> password validity period control ------ chage

Format: chage [Option] User Name

Common command: chage-d 0 user name [requires the user to change the password upon initial logon]

-L list password validity period information

-E specifies the Account expiration time YY-MM-DD

-I specifies how many days after the password expires to lock the account

-M: specifies the minimum number of days for password invalidation

-M specifies the maximum number of days for password invalidation

5> delete user ------ userdel

Format: userdel [Option] User Name

Userdel username [Delete only user accounts, do not delete data such as home directories and email files]

Userdel-r username [delete all user data]

6> view User id ------ id

View the user's id: id

View the user id: id Username

Only the IDs of private groups are listed: id-g username and id-gn username.

Only column IDs with public groups: id-G username and id-Gn Username

-N indicates the display name of the logo.