What is the role of the /etc/shadow file?

The /etc/shadow file plays a crucial role in system security by storing hashed password information for user accounts. When a user sets or changes their password, the system doesn't store the actual password in the file, which would pose a security risk; instead, it stores a hashed version of the password. This way, even if the /etc/shadow file is accessed by unauthorized entities, they cannot easily retrieve the original passwords.

Each entry in the /etc/shadow file corresponds to a user account and includes not just the hashed password but also other important information, such as password expiration policies and account locking details. This ensures that even if a user account is compromised, the actual password remains protected through secure hashing algorithms.

The other options, while related to user accounts in some capacity, do not accurately describe the primary function of the /etc/shadow file.