\section{User Accounts}

\begin{frame}
   {Purpose of User Accounts}

   \begin{itemize}
      \item Providing each user with their own individualized
      private space.
      \item Creating particular user accounts for specific
      dedicated purposes.
      \item Distinguishing privileges among users.
   \end{itemize}


\end{frame}

\cprotect\note{


   \textbf{Linux} systems provide a \textbf{multi-user}
   environment which permits people and processes to have
   separate simultaneous working environments.

   One special user account is for the \textbf{root} user,
   who is able to do \textbf{anything} on the system. To
   avoid making costly mistakes, and for security reasons,
   the root account should only be used when absolutely
   necessary.

   Normal user accounts are for people who will work on
   the system. Some user accounts (like the
   \textbf{daemon} account) exist for the purpose of
   allowing processes to run as a user other than root.

   We will also have a discussion of \textbf{group}
   management where subsets of the users on the system can
   share files, privileges etc. according to common
   interests.

}


\begin{frame}
   {Attributes of a User Account}

   From \filelink{/etc/passwd}:
   \begin{kcode}
....
beav:x:1000:1000:Theodore Cleaver:/home/beav:/bin/bash
warden:x:1001:1001:Ward Cleaver:/home/warden:/bin/bash
dobie:x:1002:1002:Dobie Gillis:/home/dobie:/bin/bash
....
   \end{kcode}

   \begin{itemize}
      \item User name
      \item User password
      \item User identification number (\textbf{UID})
      \item Group identification number (\textbf{GID})
      \item Comment or \textbf{GECOS} information
      \item Home directory
      \item Login shell
   \end{itemize}

\end{frame}

\cprotect\note{

   \small{   Each user on the system has a corresponding line in the
      \filelink{/etc/passwd} file that describes their basic
      account attributes. (We will talk about passwords as well
      as this file later).   The seven elements here are:
      \begin{enumerate}
         \item User name

         The unique name assigned to each user.

         \item User password

         The password assigned to each user.

         \item User identification number (\textbf{UID})

         A unique number assigned to the user account. The
         \textbf{UID} is used by the system for a variety of
         purposes, including a determination of user privileges
         and activity tracking.

         \item Group identification number (\textbf{GID})

         Indicates the primary, principal, or default
         \textbf{group} of the user.

         \item Comment or \textbf{GECOS} information

         A defined method to use the comment field for contact
         information (full name, email, office, contact number).
         (Do not worry about what \textbf{GECOS} means, it is a
         very old term.)

         \item Home directory

         For most users, this is a unique directory that offers a
         working area for the user. Normally, this directory is
         owned by the user, and except for \textbf{root} will be
         found on the system somewhere under \filelink{/home}.

         \item Login shell

         Normally, this is a shell program such as
         \textbf{/bin/bash} or \textbf{/bin/csh}. Sometimes,
         however, an alternative program is referenced here for
         special cases.  In general, this field will accept any
         executable.
      \end{enumerate}
   }
}



