Linux Essentials Chapter 9 Exam Answer 2016

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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