• Definition: The /etc/passwd file is a system file on Unix-like operating systems that contains essential information about user accounts.
• Function: Stores user account information necessary for user login and system processes, but not passwords.
• Components: Each line in the /etc/passwd file represents a user account and consists of several fields separated by colons:

   1. **Username**: The user’s login name.
   2. **Password Placeholder**: An 'x' indicating that the password is stored in the /etc/shadow file.
   3. **User ID (UID)**: A unique identifier for the user.
   4. **Group ID (GID)**: A unique identifier for the user’s primary group.
   5. **GECOS**: A field that typically contains the user's full name and other information.
   6. **Home Directory**: The absolute path to the user’s home directory.
   7. **Shell**: The command interpreter or shell assigned to the user.

• Features:

   * Provides necessary information for user authentication and login.
   * Used by various system processes to retrieve user-related information.
   * Contains publicly readable information, but passwords are stored in /etc/shadow for security.

• Usage: Essential for system administration, used to manage and retrieve user account information.

• Sample entry in /etc/passwd:

   ```plaintext
   john:x:1001:1001:John Doe,,,:/home/john:/bin/bash
   ```

 * **john**: Username
 * **x**: Password placeholder (indicates the actual password is in /etc/shadow)
 * **1001**: User ID (UID)
 * **1001**: Group ID (GID)
 * **John Doe,,,:**: GECOS field
 * **/home/john**: Home directory
 * **/bin/bash**: Shell

• Viewing the /etc/passwd file:

   ```bash
   cat /etc/passwd
   ```

• Adding a new user (modifies /etc/passwd):

   ```bash
   sudo useradd newuser
   ```

• /etc/passwd: A critical system file on Unix-like operating systems that contains user account information, necessary for user login and system processes, with passwords securely stored in the /etc/shadow file.