Why loops repeat tasks efficiently in Bash Scripting - Challenge Your Understanding

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a simple for loop

What is the output of this bash script?

Bash Scripting

for i in 1 2 3; do echo "Number $i"; done

A Number 1 Number 2 Number 3

B

Number 1
Number 2
Number 3

C

1
2
3

D

Number 1
Number 2

💡 Hint

Look at how the echo command prints each item on a new line.

The for loop iterates over the list 1 2 3, printing 'Number' followed by each number on its own line.

💻 Command Output

intermediate

While loop counting down

What will this bash script output?

Bash Scripting

count=3
while [ $count -gt 0 ]; do
echo "Counting $count"
count=$((count - 1))
done

A

Counting 3
Counting 2
Counting 1

B

Counting 3
Counting 2
Counting 1
Counting 0

C

Counting 1
Counting 2
Counting 3

D

Counting 3
Counting 2

💡 Hint

The loop runs while count is greater than zero.

The while loop prints the current count and decreases it until it reaches zero, then stops.

📝 Syntax

advanced

Identify the syntax error in this for loop

Which option shows the correct syntax for a bash for loop that prints numbers 1 to 3?

Bash Scripting

for i in 1 2 3 do
 echo $i
 done

A for i in 1 2 3; do echo $i; done

B for i in (1 2 3) do echo $i done

C for i in 1 2 3 do echo $i done

D for i 1 2 3; do echo $i; done

💡 Hint

Remember the semicolon before 'do' is required.

Option A uses the correct syntax with 'in' keyword, semicolon before 'do', and proper loop body.

🔧 Debug

advanced

Why does this while loop run infinitely?

What is the reason this bash script runs forever?

Bash Scripting

count=1
while [ $count -le 3 ]
do
echo $count
done

A The condition uses '-le' which is invalid in bash.

B The while loop syntax is incorrect; it needs a semicolon before 'do'.

C The echo command is missing quotes.

D The variable 'count' is never updated inside the loop.

💡 Hint

Check if the loop changes the variable controlling the condition.

The loop never changes 'count', so the condition is always true, causing an infinite loop.

🚀 Application

expert

Create a loop to list all .txt files with line counts

Which bash script correctly lists all '.txt' files in the current folder and prints their line counts?

A for file in *.txt; do wc -l "$file"; done

B ls *.txt | while read file; do echo "$file: $(wc -l < "$file") lines"; done

C for file in *.txt; do echo "$file: $(wc -l < "$file") lines"; done

D for file in *.txt; do echo "$file: wc -l $file"; done

💡 Hint

Use command substitution and redirect wc input to avoid extra filename in output.

Option C uses a for loop with command substitution and input redirection to print only line counts with filenames.