Week 7 Comprehension

Question 1

Which command will display the following information?

The number of different shells being used on a Linux system

$ cat /etc/passwd | cut -d: -f7 | uniq | sort | wc -l
$ cat /etc/passwd | cut -d: -f7 | wc -l | sort | uniq
$ cat /etc/passwd | cut -d: -f7 | sort | wc -l | uniq
$ cat /etc/passwd | cut -d: -f7 | sort | uniq | wc -l

Answer 1

$ cat /etc/passwd | cut -d: -f7 | sort | uniq | wc -l

Question 2

Find the match.

stderr()
stdout()
stdin()
|

0
1
Pipe
2

Answer 2

stderr() =2
stdout() =1
stdin() =0
| = Pipe

Question 3

Which numeric variable test expressions work? (Select two)

A (($A == $B))
B ((! $A -eq $D))
C (($A != $C))
D ((! $A = $D))

Answer 3

A. (($A == $B))

C. (($A != $C))

Question 4

! /bin/bash

What will be displayed? Assume the script has the execution bit set.

$ cat myscript.sh

echo “$0 $@ $1 $2”

• Nothing
• Hello World!
• ./myscript.sh Hello World!
• ./myscript.sh Hello World! Hello World!

Answer 4

• ./myscript.sh Hello World! Hello World!

Question 5

Which commands will work? (Select two)

$ ls > file1
$ file1 > file2
$ wc < file1
$ wc | file1

Answer 5

$ ls > file1

$ wc < file1

Question 6

What is Git?

• Another name for Gigabit
• Version control software
• Configuration management software
• Open source malware

Answer 6

• Version control software

Question 7

What does export a variable mean?

• Allow the variable to become accessible by child processes
• Allow the variable to become accessible by parent process
• Send the variable to a file
• Send the variable to foreign countries

Answer 7

-Allow the variable to become accessible by child processes

Question 8

Suppose file1 exists but dir1 does not. Which command will write stdout and stderr to the same file? (Select two)

$ cat file1 dir1 2>file
$ cat file1 dir1 >file 2>&1
$ cat file1 dir1 2>&1 >file
$ cat file1 dir1 &>file

Answer 8

$ cat file1 dir1 >file 2>&1

$ cat file1 dir1 &>file

Question 9

Which commands will work? (Select two)

$ ls > file1
$ file1 > file2
$ wc < file1
$ wc | file1

Answer 9

$ ls > file1

$ wc < file1

Question 10

! /bin/bash

What will be displayed? Assume the script has the execution bit set.

$ cat myscript.sh

function print_positional_params () {

echo “$3 $1 $2”

}

print_positional_params “$3” “$2” “$1”

• one two three
• one three two
• two three two
• three one two

Answer 10

• one three two