What is the primary function of the 'passwd' command in Linux?

The primary function of the 'passwd' command in Linux is to change a user's password. This command is widely used for updating the password associated with a specific user account, allowing users to secure their accounts. When executed, the command will prompt for the current password (if applicable) and then require the new password to be entered twice for confirmation.

It’s important to note that this command helps maintain system security, as it enables users to change their passwords regularly or in response to potential security issues. The command can also be run by the root user to change the passwords of other users on the system, reinforcing its significance in user account management.

In terms of the other options, while user management is crucial in Linux systems, commands like 'userdel' are used to delete a user, 'useradd' is utilized to create new users, and user information can be displayed using commands like 'getent' or 'finger'. None of these alternatives directly relate to the function of changing a user’s password, thereby making the function of the 'passwd' command distinct and essential in user account security.