Multiuser

Multi - User

UNIX intrinsically supports multiple users.

Many users can share one host computer at the same time.

One person can switch from one user to another.

su: Switch user.

Example:

> su root

users / who: Print users currently logged in.

Example:

> who

root     tty2     Oct 20 12:50
felix    :0       Oct 20 09:37 (console)
felix    pts/0    Oct 20 12:50

whoami / id : Print real and effective UIDs and GIDs.

       id [OPTION]... [USERNAME]

Example:
> id
uid=500(felix) gid=100(users) groups=100(users),14(uucp),....

passwd: Change user password.