Exam Bash Scripting

Attachment : To solve questions 14 and 15, you need to download the attached files.

FILE NAME matryoshka_bash.zip
PASS hackviser
MD5 b5c6693d3cdf12c56c1dd3cb2a5fc6a8
---------------------------------
FILE NAME decoder_bash.zip
PASS hackviser
MD5 4f9445e7939b6d2797ef3737b75df89a

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Question 1: What symbol is used for a single-line comment within a shell script?

==> The Answer : #

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Question 2: Shell script files typically have which file extension?

==> The Answer : sh

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Question 3: Which of the following variable names is invalid?

• username
• _username
• username2
• 2username

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Question 4: What symbol is used to access a variable?

• $
• #
• &
• %

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Question 5: Which of the following is incorrect for defining an array in the shell?

• array_name[index]=value
• declare -a array_name
• array_name=(value1 value2 … valueN)
• array_name={value1, value2, … valueN}

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Question 6: What is the method to access the first element of an array in the shell?

• ${arr[1]}
• ${arr[0]}
• ${arr[-1]}
• ${arr[first]}

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Question 7: How is an if statement ended in a shell script?

==> The Answer : fi

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Question 8: Which condition checks if a number is greater than 10?

• [ $number -lt 10 ]
• [ $number -eq 10 ]
• [ $number -gt 10 ]
• [ $number -ne 10 ]

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Question 9: Which expression checks if a number is even?

• [ $((number % 2)) -eq 0 ]
• [ $((number / 2)) -eq 0 ]
• [ $number -eq 2 ]
• [ $number % 2 -eq 0 ]

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Question 10: What keyword is used to exit the current loop?

==> The Answer : break

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Question 11: What keyword is used to skip the current iteration in a loop?

==> The Answer : continue

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Question 12: What keyword is used to return a value from a function?

==> The Answer : return

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Question 13: What is the syntax for defining a function in shell scripts?

• myFunc() { commands }
• def myFunc() { commands }
• def myFunc: { commands }
• func myFunc = {commands}

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Question 14: What is the password found in the “password.txt” file obtained after extracting the nested zip files within “matryoshka_bash.zip” using shell scripting?

-Tôi dùng scrip như sau :

kai0kid@Kai0Kid:~/Temp$ cat uzip.sh
#!/bin/bash

name=10000

while [ $name -gt 0 ]; do
    echo "[+] Extracting $name.zip ..."
    unzip -o "$name.zip" >/dev/null 2>&1

    name=$((name - 1))

    if [ ! -f "$name.zip" ]; then
        echo "[✓] Hết file ZIP. Dừng lại."
        break
    fi
done
kai0kid@Kai0Kid:~/Temp$ chmod +777 unzip.sh
kai0kid@Kai0Kid:~/Temp$ ./unzip.sh
....

Sau khi giải nén toàn bộ thì sẽ có 1 tệp tin :

kai0kid@Kai0Kid:~/Temp$ cat password.txt
capella
kai0kid@Kai0Kid:~/Temp$

==> The Answer : capella

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Question 15: What is the plaintext obtained after successfully running the corrected shell script within “decoder_bash.zip”?

==> The Answer : canopus