Account

Account in Linux

• Definition: A user account in Linux represents a unique identity used to log in and interact with the system.
• Structure:
• /etc/passwd: Stores user account information.
  • Format: username:x:UID:GID:comment:home_directory:shell
  • Example: john:x:1001:1001:John Doe:/home/john:/bin/bash
• /etc/shadow: Stores encrypted passwords and password-related information.
  • Format: username:encrypted_password:last_change:min:max:warn:inactive:expire:flag
• /etc/group: Defines user groups.
  • Format: group_name:x:GID:user_list
  • Example: developers:x:1002:john,mary
• Home Directory: /home/username
  • Contains user-specific files and settings.
  • Example: /home/john for user ‘john’.
• Purpose:
• Provides personalized environments.
• Controls access to files, processes, and system resources.
• Allows for user-specific configurations and data storage.
• Key Files and Directories:
• /home/: Directory where all user home directories reside.
• /etc/passwd: Main user account information file.
• /etc/shadow: Secure storage of user passwords.
• /etc/group: Group membership definitions.

Uses in Linux:

• Authentication: Verifies user identity during login.
• Authorization: Grants permissions to access files and execute commands.
• Customization: Allows users to have personal settings and preferences.
• Resource Management: Isolates user processes and files for security and organization.

Key Points:

• Essential for multi-user environment management.
• Supports both individual and group-based permissions.
• Configurable through command-line tools like useradd, usermod, and passwd.