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.

Expand all answers

??? question "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

??? question "2. How do you iterate over files in a directory?" Using a glob pattern:

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

??? question "3. How do you declare an array in Bash?" my_array=("value1" "value2" "value3").

??? question "4. How do you access an element of an array?" ${array_name[index]}.

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

??? question "5. How do you get the length of an array?" ${#array_name[@]}.

??? question "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).

??? question "7. How do you create an infinite loop?" while true; do ... done or for ((;;)); do ... done.

??? question "8. How do you break out of a loop?" break.

It immediately terminates the loop execution.

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

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

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

??? question "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.

??? question "12. How do you check if two strings are equal?" if [ "$str1" == "$str2" ]; then ....

Always quote variables to handle spaces/empty values correctly.

??? question "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.

??? question "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 ...

??? question "15. How do you extract specific columns from output?" Using awk or cut.

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

??? question "16. How do you perform arithmetic operations?" $(( expression )).

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

??? question "17. What is command substitution?" Assigning the output of a command to a variable.

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

??? question "18. How do you get the current date in specific format?" date +"%Y-%m-%d".

??? question "19. How do you check the disk usage of a specific directory?" du -sh directory_name.

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

??? question "20. How do you find files modified in the last n minutes?" find . -type f -mmin -n.

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