Which file is commonly used for user account management in Linux?

The file commonly used for user account management in Linux is /etc/passwd. This file plays a crucial role in maintaining information about user accounts on the system. It contains essential details for each user, such as the username, user identifier (UID), group identifier (GID), home directory, and the default shell that the user will use upon login.

Each line in the /etc/passwd file corresponds to a specific user account, structured in a standardized format. This makes it easy for various applications and system utilities to access and manage user account information when managing authentication and authorization processes.

While /etc/shadow also contains crucial information for user account management, specifically related to passwords and account expiration, its primary function is to store password hashes and security settings that are not typically accessed directly by standard users. The other choices, such as /var/log/auth.log, which logs authentication events, and /etc/fstab, which configures file system mounting, serve different functions not directly tied to user account management.