Sec. 11: User Accounts and Groups

Unlike other Operating Systems, Linux is a single-user operating system.

• True

• False

Answer explanation

False, Linux is a multi-user operating system.

Most account features are defined in the /etc/passwd file, except:

• Username

• Password

• Connection type

Answer explanation

The username and password is contained in the /etc/passwd, but the connection type is not.

A __________ uses a one-way mathematical process with additional random input to produce what looks like nonsense to humans.

• salted hash

• password encryption

• firewall

Answer explanation

A salted hash uses a one-way mathematical process with additional random input to produce what looks like nonsense to humans.

The /etc/shadow file is usually stored with restrictive permissions, with ownership by root.

• True

• False

Answer explanation

Since the /etc/shadow file contains the passwords of all the users on a system, it must have the most restrictive permissions.

The fields in /etc/group contains the following:

• Shell, Kernel, Package Information

• Group Name, Password, GID

• IP address, metamask, domain name

Answer explanation

The group name, password, and GID are located in the /etc/group file.

Linux does not allow multiple users to access the computer simultaneously.

• True

• False

Answer explanation

False, Linux is a multi-user operating system, therefore multiple users may simultaneously log on to it.

Information provided in the default output of the who command includes the following:

• Username, password, ip address

• GID, UID, password

• Username, Terminal Identifier, Login Date and Time

Answer explanation

Information such as the username, terminal identifier, login date, and login time are shown using the who command.

The _________ column tells what program the session is running.

• STATUS

• PROGRAM

• WHAT

Answer explanation

The WHAT column tells the user what program the session is running in.

Linux limits the number of user accounts in a single computer to 100.

• True

• False

Answer explanation

False, but you can limit the number of processes launched a single user, if desired.

Which of the following ways can you not run a command-line task as the root user?

• Log in directly as root at a text-mode shell or by using a remote login tool such as SSH.

• Disabling firewall and force open a directory, file or folder

• By using the sudo command

Answer explanation

If you need to run a single task as the root user, you can use sudo. Alternatively, you can also log in directly as root, and then run the task.