This chapter explains how user accounts work, how users can change their
password by using the passwd utility,
and how system administrators can use the passwd utility
and edit account database files to create and
maintain users' accounts.
Note:
In embedded systems, the designer may choose to eliminate the
account-related files from the system, disabling logins and references
to users and groups by name, even though the system
remains fully multiuser and may have multiple numeric user IDs running
programs and owning system resources.
If your system is configured this way, most of this chapter won't be relevant
to you.