Examining User Information

Question 1

The id command displays…?

Answer 1

user and group information.

Question 2

The whoami reports the…?

Answer 2

current username.

Question 3

The who, users, and w commands report …?

Answer 3

users with active sessions.

Question 4

id -g, –group …?

Answer 4

Print only effective group id

Question 5

id -G –groups ..?

Answer 5

Print all group ids

Question 6

id -u, –user …?

Answer 6

Print only effective user id.

Question 7

id -n, –name …?

Answer 7

Print user or group name instead of number.

Question 8

If called without arguments, the id command returns…?

Answer 8

a summary of group memberships for the user who ran it. If supplied with a username, the id command reports group information for the specified user.

Question 9

By default, ls reports the….?

Answer 9

user’s user id, primary group and primary group id, and all groups (primary and secondary) to which the user belongs, both by group name and group id.

Question 10

The output of the id command can be qualified with…?

Answer 10

the command line switches.

Question 11

The id command can report…?

Answer 11

one or more piece of information, starting with context=, known as the SELinux context.

Question 12

SELinux, or “Security Enhanced Linux”, involves …?

Answer 12

topics which will be covered in more detail in later course, and for now can be safely ignored.

Question 13

The whoami command simply…?

Answer 13

reports the current user’s username.

Question 14

In Red Hat Enterprise Linux, there is seldom a need to use the whoami command, because…?

Answer 14

the default bash prompt displays the current user’s username. The prompt is configurable, however, and on other Linux or Unix systems, or in other environments (such as rescue shells), a user’s identity might not be as obvious. Also, the whoami command can be embedded in a script, which could take on different behavior depending on who’s running it.

Question 15

Often, a user would like to know who else is using a particular Linux or Unix machine. Red Hat Enterprise Linux provides three commands which report current users, each at a different level of detail. THe simplest of these is the…?

Answer 15

users command.

Question 16

The w command lists…?

Answer 16

current logged on users, but provides much more detailed information.

Question 17

w command:

User…?

Answer 17

The username of the logged user

Question 18

w command:

TTY…?

Answer 18

The terminal that the user logged in from. (Interpreting terminals is discussed in Workbook 1 (Quick Tour)).

Question 19

w command:

FROM…?

Answer 19

If the user is logged in over the network, the host name that the user connected from.

Question 20

w command:

LOGIN@…?

Answer 20

The time that the user started the session.

Question 21

w command:

IDLE…?

Answer 21

How much time has expired since the terminal has seen interaction.

Question 22

w command:

JCPU…?

Answer 22

The amount of CPU time consumed by all currently running processes associated with the terminal session.

Question 23

w command:

PCPU…?

Answer 23

The amount of CPU time consumed by the only current process only, as named in the “WHAT” field.

Question 24

w command:

WHAT…?

Answer 24

The user’s currently running process.

Question 25

Who command provides…?

Answer 25

detailed information about who is currently logged on. Called without arguments, it behaves similarly to the w command. The who command is also designed to report system events, such as the current runlevel, system clock adjustments, and processes automatically spawned by the /sbin/init process.

Question 26

The finger command can be used to..?

Answer 26

“check up” on a user, to see not only if that user is logged on, but if the have read their mail, what time they last logged in, and other information as well.

Question 27

Without arguments, the finger command acts much like the who command, giving…?

Answer 27

information including a user’s terminal (Tty), login time, and idle time.

Question 28

A user can customize the information someone sees when they are fingered, by…?

Answer 28

creating specially named hidden files in their home directory.

Question 29

Files known by the finger command:

.plan…?

Answer 29

Displayed by the finger command, under the heading “Plan”

Question 30

Files known by the finger command:

.project…?

Answer 30

Displayed by the finger command, under the heading “Project”

Question 31

Files known by the finger command;

.pgpkey…?

Answer 31

Displayed by the finger command, under the heading “PGP Key” This is a convenient way for a user to publish the public key portion of a public/private key pair used in public key encryption.

Question 32

My default in Red Hat Enterprise Linux, a user’s home directory is completely inaccessible to…?

Answer 32

other users on the system. In order for the finger command to find these files, a user must execute permissions on their home directory, using a command similar to the following: ( chmod o+x ~)

Question 33

The finger command can report user activity on…?

Answer 33

remote machines, as well. For the command to work, the remote machine nimbus.example.com must elect to run the finger service. In the early days of the Internet, Unix machines commonly ran this service. Now that the Internet has grown, and the demands of security often outweigh the spirit of the community, most admin choose to not run the finger services.