Linux Essentials – Chapter 09 Exam Answers 2019 + PDF file

1. The echo command:

• Is used for variable assignment
• Duplicates the input stream to the output stream
• Is used to output text to the console
• Tests a variable for duplication
• Copies variables from one to another

2. A file begins with #!/bin/csh. This means:

• Nothing, this is a comment
• C Shell compatibility mode is enabled
• The operator should not be using /bin/csh
• Running the script will invoke /bin/csh to interpret the rest of the file
• This is a Perl script

3. Which are appropriate editors for writing shell scripts? (choose two)

• /bin/bash
• vi
• LibreOffice Writer
• Firefox
• nano

4. Most of nano’s commands take the form of:

• Control and another character
• Alt and another character
• Mouse clicks
• The F1 through F12 function keys
• Escape followed by another character

5. What does this shell script do?
FOO=/tmp/foo
if [ ! –d $FOO ]; then
     mkdir $FOO
fi

• Creates /tmp/foo if it does not exist
• Makes the /tmp/foo directory if a file by that name exists
• Outputs a message to the screen
• Creates /tmp/foo and raises an error if there is a problem
• Nothing, since there is a problem with the conditions in the if statement

6. Which of the following are correct about for and while loops? (choose two)

• for loops operate over a fixed list of items
• while loops operate over a fix list of items
• for loops have a test each cycle to determine if it should run again
• while loops have a test each cycle to determine if it should run again
• for loops require a variable over which to iterate

7. Given the following part of a script:
if [ -f $1 ]; then
echo “I am here”
fi
What is the meaning of $1?

• It is a special variable that indicates the exit code of the command before it
• It is the first argument passed to the script
• It is a file called $1
• It is a parameter to –f, indicating the size of the file
• It is a list of files that gets interpolated

8. Given the following script that is run through ./test.sh hello goodbye:
if [ -f $2 ]; then
    echo “I am here”
fi

When will “I am here” be printed?

• If there are two files in the current directory
• The script will always print “I am here”
• Never
• If a file called “hello” exists in the current directory
• If a file called “goodbye” exists in the current directory

9. What is the correct way to assign the word “Hello” to a variable?

• $A=”Hello”
• echo “Hello” > A
• A=”Hello”
• echo $A “Hello”
• A = “Hello”

10. What is the correct way to save the current directory to a variable?

• A=`pwd`
• A=pwd
• A=cwd
• pwd $A
• pwd | $A

11. Which shell command accepts input from the user’s keyboard?

• echo
• $1
• read
• input
• gets

12. What information is held inside $?

• The current process id
• The number of arguments passed to the script
• The current user ID
• The previous command’s exit code
• The name of the command run

13. How would you finish your script with an exit code of 42?

• return 42
• $?=42
• CODE=42
• exit 42
• break 42

14. The if command looks for what exit code to consider a condition to be true?

• 10
• 255
• 0
• 1
• 8

15. The number of users logged in is in a variable called USERS. How would you test to see if 5 users are logged in?

• test –f USERS=5
• test $USERS = 5
• test $USERS,5
• test $USERS –eq 5
• test $USERS –a 5

16. Given the following script:
while [ ! –f /tmp/foo ]; do
echo –n “.”
process_data > /tmp/foo
done
Which of the following are true? (choose two)

• If a file called /tmp/foo exists, process_data won’t be run
• The screen will fill with dots.
• /tmp/foo will be removed if it exists
• process_data will never be run
• process_data will be called at most once

17. A conditional that lets you make multiple comparisons with a pattern is called:

• case
• fanout
• if
• test
• branch

18. What is the meaning of $(( $i + 1)) ?

• 1 will be added to the i variable
• This will return the value of the next argument to the script
• This runs the command stored in variable i
• If i is 0, the loop will stop
• This will return the value of the first argument to the script

19. How would you write a test that says “if /tmp/foo is a directory or USERS is greater than 5”?

• test –d /tmp/foo | $USERS > 5
• test –f /tmp/foo –o $USERS –ge 5
• test –d /tmp/foo –o $USERS –gt 5
• test /tmp/foo || $USERS > 5
• test /tmp/foo –d –o $USERS -gt 5

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