Writing to files (echo, printf) in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the content of the file after running this script?

Consider the following bash script that writes to a file named output.txt. What will be the content of output.txt after running it?

Bash Scripting

echo "Hello World" > output.txt
printf "Line1\nLine2\n" >> output.txt

A Hello World\nLine1\nLine2

B Hello World\nLine1 Line2

C Hello World

D Line1\nLine2

💡 Hint

Remember that > overwrites the file and >> appends to it.

The first command writes "Hello World" and overwrites any existing content. The second command appends two lines: "Line1" and "Line2". So the file contains three lines in total.

💻 Command Output

intermediate

What does this command write to the file?

What will be the exact content of data.txt after running this command?

Bash Scripting

printf "%s\n" "apple" "banana" "cherry" > data.txt

A apple\nbanana\ncherry

B apple\nbanana\ncherry\n

C apple\nbanana cherry

D apple banana cherry

💡 Hint

Each %s\n prints the string followed by a newline.

The printf command prints each string followed by a newline, so the file ends with a newline after "cherry".

📝 Syntax

advanced

Which option correctly appends a line with a variable to a file?

You want to append the text "User: alice" to a file named log.txt, where the username is stored in a variable user. Which command is correct?

Bash Scripting

user=alice

A printf 'User: $user\n' >> log.txt

B echo 'User: $user' >> log.txt

C printf "User: $user\n" > log.txt

D echo "User: $user" >> log.txt

💡 Hint

Think about how single and double quotes handle variables.

Double quotes allow variable expansion, so $user becomes 'alice'. Single quotes do not expand variables, so $user is written literally. Also, >> appends, > overwrites.

🔧 Debug

advanced

Why does this script not write the expected content to the file?

This script is intended to write "Count: 5" to count.txt. Why does it fail?

Bash Scripting

count=5
echo 'Count: $count' > count.txt

A Because single quotes prevent variable expansion, so $count is written literally.

B Because echo does not support variables.

C Because the file count.txt is read-only.

D Because the > operator only works with printf.

💡 Hint

Check how quotes affect variables inside echo.

Single quotes prevent the shell from expanding variables, so the literal string 'Count: $count' is written instead of 'Count: 5'.

🚀 Application

expert

How to write a multi-line formatted report to a file using printf?

You want to create a report file report.txt with the following content exactly (including newlines):

Report Summary:
- Total: 10
- Passed: 8
- Failed: 2
End of Report

Which command correctly writes this using a single printf command?

A echo -e "Report Summary:\n- Total: 10\n- Passed: 8\n- Failed: 2\nEnd of Report" > report.txt

B printf 'Report Summary:\n- Total: 10\n- Passed: 8\n- Failed: 2\nEnd of Report\n' > report.txt

C printf "Report Summary:\n- Total: %d\n- Passed: %d\n- Failed: %d\nEnd of Report\n" 10 8 2 > report.txt

D

printf "Report Summary:
- Total: 10
- Passed: 8
- Failed: 2
End of Report" > report.txt

💡 Hint

Use printf format specifiers and escape sequences carefully.

Option C uses printf with format specifiers %d and newline escapes \n correctly, writing the exact formatted report with variables.