====== User Management ======
User management in Linux is a critical aspect of system administration. It involves creating, modifying, and managing user accounts and groups to ensure proper access control, system security, and resource allocation. Each user is assigned a unique identity, along with permissions and restrictions.
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Add user: 
  adduser 

Delete user: 
  deluser 

Add group: 
  groupadd

Delete group: 
  groupdel

Change user password: 
  passwd

Lock/unlock user password: 
  passwd -l
  passwd -u

Switch user: 
  su

Show user information: 
  id

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  * **Change user password**

1. Type this command to change user password.
  sudo passwd username

2. Enter new password. Then, you will be ask to retype your new password.

3. Your password is changed successfully.

{{:screenshot_2025-01-16_144702.png?nolink&600|}}

  * **Manage password aging and expiration**

The ''sudo chage'' command is used in Linux to manage password aging and expiration policies for a user. It allows administrators to define and control how long a user's password remains valid, enforce password expiration, and specify warnings before password expiration.

The syntax is: ''sudo chage [option] username''

1. Displays the current password aging information.
  sudo chage -l username

{{:screenshot_2025-01-16_162659.png?nolink&600|}}

2. Set the account expiration date. 
  sudo chage -E  2025-12-31 username

{{:date.png?nolink&600|}}

The account will be disabled after this 2025-12-31. To set account expiration to **never:**
  sudo change -E -1 username

3. Set a warning to the user 7 days before the password expires.
  sudo chage -W 7 username

{{:date.png?nolink&600|}}
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Good user management is essential to make sure your system stay secure from unknown intruders.