Cit 352 Chapter 7

Front 1

Because stderr and stdout represent the results of a command and stdin represents the input required for a command, only stderr and stdout can be redirected to/from a file.True or False?

Back 1

False

Front 2

Before a user-defined variable can be used by processes that run in subshells, that variable must be ________________.

a. imported

b. validated by running the env command

c. exported

d. redirected to the BASH shell

Back 2

c. exported

Front 3

The alias command can be used to make a shortcut to a single command. True orFalse?

Back 3

True

Front 4

Which of the following files is always executed immediately after a user logs in to a Linux system and receives a BASH shell?

a. /etc/profile

b. ~/.bash_profile

c. ~/.bash_login

d. ~/.profile

Back 4

a. /etc/profile

Front 5

Which command could you use to see a list of all environment and user-defined shell variables as well as their current values?

a. ls /var

b. env

c. set

d. echo

Back 5

c. set

Front 6

Every if construct begins with if and must be terminated with ________________.

a. end

b. endif

c. stop

d. fi

Back 6

d. fi

Front 7

Which of the following will display the message welcome home if the cd /home/user1command is successfully executed?

a. cd /home/user1 && echo “welcome home”

b. cat “welcome home” | | cd /home/user1

c. cd /home/user1 | | cat “welcome home”

d. echo “welcome home” && cd /home/user1

Back 7

a. cd /home/user1 && echo “welcome home”

Front 8

The current value for the HOME variable is displayed by which of the following commands?(Choose all that apply.)

a. echo HOME=

b. echo ~

c. echo $HOME

d. echo ls HOME

Back 8

c. echo $HOME

Front 9

Which of the following file descriptor numbers represents stdout?

a. 2

b. 0

c. 1

d. 3

Back 9

c. 1

Front 10

Which of the following operators reverses the meaning of a test statement?

a. #!

b. −o

c. −a

d. !

Back 10

d. !

Front 11

What would be the effect of using the alias command to make an alias for the date command named cat in honor of your favorite pet?

a. It cannot be done because there already is an environment variable cat associated with the cat command.

b. It cannot be done because there already is a cat command on the system.

c. When you use the cat command at the command prompt with the intention of viewing a text file, the date appears instead.

d. There is no effect until the alias is imported, because it is a user-declared variable.

Back 11

c. When you use the cat command at the command prompt with the intention of viewing a text file, the date appears instead.

Front 12

How do you indicate a comment line in a shell script?

a. There are no comment lines in a shell script.

b. Begin the line with #!.

c. Begin the line with !.

d. Begin the line with #.

Back 12

d. Begin the line with #.

Front 13

You have redirected stderr to a file called Errors. You view the contents of this file afterward and notice that there are six error messages. After repeating the procedure, you notice that there are only two error messages in this file. Why?

a. After you open the file and view the contents, the contents are lost.

b. The system generated different stdout.

c. You did not append the stderr to the Error file, and, as a result, it was overwritten when the command was run a second time.

d. You must specify a new file each and every time you redirect, because the system creates the specified file by default.

Back 13

c. You did not append the stderr to the Error file, and, as a result, it was overwritten when the command was run a second time.

Front 14

The sed and awk commands are filter commands commonly used to format data within a pipe. True or False?

Back 14

True

Front 15

What is wrong with the following command string: ls /etc/hosts >listofhostfile?

a. Nothing is wrong with the command.

b. The file descriptor was not declared; unless 1 for stdout or 2 for stderr is indicated, the command will fail.

c. The ls command is one of the commands that cannot be used with redirection. You must use | to pipe instead.

d. The file listofhostfile will always only contain stderr because a file descriptor was not declared.

Back 15

a. Nothing is wrong with the command.

Front 16

Which of the following is not necessarily generated by every command on the system? (Choose all that apply.)

a. standard input

b. standard deviation

c. standard output

d. standard error

Back 16

b. standard deviation

Front 17

Which construct can be used in a shell script to read stdin and place it in a variable?

a. read

b. sum

c. verify

d. test

Back 17

a. read

Front 18

A for construct is a loop construct that processes a specified list of objects. As a result,it is executed as long as there are remaining objects to process. True or False?

Back 18

True

Front 19

What does >> accomplish when entered on the command line after a command?

a. It redirects both stderr and stdout to the same location.

b. It does not accomplish anything.

c. It redirects stderr and stdin to the same location.

d. It appends stdout to a file.

Back 19

d. It appends stdout to a file.

Front 20

Consider the following shell script:

echo -e "What is your favorite color?--> \c"

read REPLY

if [ "$REPLY" = "red" –o "$REPLY" = "blue" ]

then

echo "The answer is red or blue."

else

echo "The answer is not red nor blue."

fi

1. What would be displayed if a user executes the program and answers Blue when prompted?

a. The answer is red or blue.

b. The answer is neither red nor blue.

c. The code would cause an error.

d. The answer is red or blue. The answer is not red nor blue.

Back 20

b. The answer is neither red nor blue.