Intermediate Questions¶

How to use these interview questions

🧠 Read each question carefully.

Try answering it yourself before expanding the answer to compare with the ideal response.

Level: Intermediate

🟡 Practical Applications & Troubleshooting.

Focus on real-world scenarios, debugging, optimization, and deeper configuration.

1. What is the syntax for a for loop in Bash?

Method 1 (Range):

for i in {1..5}; do
    echo "Number: $i"
done

Method 2 (C-style):

for ((i=1; i<=5; i++)); do
    echo "Number: $i"
done

2. How do you iterate over files in a directory?

Using a glob pattern:

for file in *.txt; do
    echo "Processing $file"
done

3. How do you declare an array in Bash?

my_array=("value1" "value2" "value3").

4. How do you access an element of an array?

${array_name[index]}.

Example: echo ${my_array[0]} prints the first element.

5. How do you get the length of an array?

${#array_name[@]}.

6. What is the difference between while and until loops?

while: Executes the block as long as the condition is true.
until: Executes the block as long as the condition is false (until it becomes true).

7. How do you create an infinite loop?

while true; do ... done or for ((;;)); do ... done.

8. How do you break out of a loop?

break.

It immediately terminates the loop execution.

9. How do you skip the current iteration and move to the next?

continue.

10. How do you read a file line-by-line?

while read -r line; do
    echo "$line"
done < filename.txt

11. What is the difference between [ condition ] and [[ condition ]]?

[ ] is the old, POSIX-compliant test command.
[[ ]] is an extended Bash keyword that supports regex, logical operators (&&, ||), and is generally safer.

12. How do you check if two strings are equal?

if [ "$str1" == "$str2" ]; then ....

Always quote variables to handle spaces/empty values correctly.

13. How do you compare integers?

Use flags: * -eq (Equal) * -ne (Not Equal) * -gt (Greater Than) * -lt (Less Than) * -ge (Greater or Equal) * -le (Less or Equal) Or use (( a > b )) for arithmetic context.

14. How do you check if a file is readable, writable, or executable?

-r: Readable
-w: Writable
-x: Executable Example: if [ -x script.sh ]; then ...

15. How do you extract specific columns from output?

Using awk or cut.

Example: ls -l | awk '{print $9}' prints the 9^th column (filename).

16. How do you perform arithmetic operations?

$(( expression )).

Example: sum=$(( 5 + 3 )).

17. What is command substitution?

Assigning the output of a command to a variable.

Syntax: $(command). Example: date=$(date +%F).

18. How do you get the current date in specific format?

date +"%Y-%m-%d".

19. How do you check the disk usage of a specific directory?

du -sh directory_name.

-s for summary, -h for human-readable.

20. How do you find files modified in the last n minutes?

find . -type f -mmin -n.

🧪 Ready to test yourself?¶

👉 Take the Intermediate Shell Scripting Quiz (Coming Soon)

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