Writing to files (echo, printf) in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to write the text 'Hello World' into a file named output.txt using echo.

Bash Scripting

echo "Hello World" [1] output.txt

Drag options to blanks, or click blank then click option'

A>>

B>

C<

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using >> appends instead of overwriting.

Using < which is for input redirection.

Using | which pipes output to another command.

The > operator redirects the output of echo to a file, overwriting it if it exists.

2fill in blank

medium

Complete the code to append the text 'New Line' to the file log.txt using echo.

Bash Scripting

echo "New Line" [1] log.txt

Drag options to blanks, or click blank then click option'

A>>

B>

C<

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using > which overwrites the file.

Using < which is for input redirection.

Using | which pipes output to another command.

The >> operator appends the output to the file without overwriting existing content.

3fill in blank

hard

Fix the error in the code to write formatted text with printf into file.txt.

Bash Scripting

printf "Name: %s\n" [1] > file.txt

Drag options to blanks, or click blank then click option'

AJohn

B'John'

C"John"

DName

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the string, causing errors or unexpected output.

Using single quotes which may not expand variables if used.

Passing a bare word that is not defined.

The argument to printf must be a string without quotes stripped by the shell, so use the string without quotes.

4fill in blank

hard

Fill both blanks to create a file with numbers 1 to 5, each on a new line, using printf and a loop.

Bash Scripting

for i in {1..5}; do printf "[1]\n" [2]; done > numbers.txt

Drag options to blanks, or click blank then click option'

A%d

Bi

C$i

D%s

Attempts:

3 left

💡 Hint

Common Mistakes

Using i without $ which is treated as a string.

Using %s which is for strings, not numbers.

Not redirecting output to the file.

Use %d as the format for integers and $i to pass the current loop value to printf.

5fill in blank

hard

Fill all three blanks to create a file with squares of numbers 1 to 3 using printf and arithmetic expansion.

Bash Scripting

for n in {1..3}; do printf "[1]: [2]\n" [3] $((n*n)); done > squares.txt

Drag options to blanks, or click blank then click option'

ANumber

BSquare

Cn

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same label twice.

Using incorrect variable names.

Not using arithmetic expansion correctly.

Use 'Number' and 'Square' as labels, and 'n' as the variable for the number in the loop.

Practice

1. Which command in bash writes the text Hello World to a file named greeting.txt and adds a newline automatically?

easy

A. echo "Hello World" > greeting.txt

B. printf "Hello World" > greeting.txt

C. echo -n "Hello World" > greeting.txt

D. printf "Hello World\n" > greeting.txt

Solution

1. Step 1: Understand echo behavior

   The echo command prints text and adds a newline by default.

2. Step 2: Compare with printf

   printf requires explicit newline characters to add a newline.

3. Final Answer:

   echo "Hello World" > greeting.txt -> Option A

4. Quick Check:

   echo adds newline automatically = A [OK]

Hint: Use echo for quick writes with newline [OK]

Common Mistakes:

• Using printf without \n misses newline
• Using echo -n suppresses newline
• Confusing > and >> operators

2. Which of the following is the correct syntax to append the line Log entry to a file log.txt using printf?

easy

A. printf "Log entry" >> log.txt

B. printf -n "Log entry" >> log.txt

C. printf "Log entry\n" >> log.txt

D. printf -e "Log entry" >> log.txt

Solution

1. Step 1: Understand printf newline requirement

   printf does not add newline automatically; you must include \n explicitly.

2. Step 2: Check append operator

   >> appends to the file without overwriting.

3. Final Answer:

   printf "Log entry\n" >> log.txt -> Option C

4. Quick Check:

   printf needs \n for newline + append with >> = C [OK]

Hint: Always add \n with printf to get a new line [OK]

Common Mistakes:

• Forgetting \n causes no newline
• Using > instead of >> overwrites file
• Using invalid printf flags like -n or -e

3. What will be the content of file.txt after running this script?

echo "Line1" > file.txt
printf "Line2\n" >> file.txt
echo -n "Line3" >> file.txt

medium

A. Line1\nLine2Line3

B. Line1\nLine2\nLine3\n

C. Line1Line2Line3

D. Line1\nLine2\nLine3

Solution

1. Step 1: Analyze echo "Line1" > file.txt

   This writes "Line1" plus newline to file.txt, overwriting existing content.

2. Step 2: Analyze printf "Line2\n" >> file.txt

   This appends "Line2" plus newline to file.txt.

3. Step 3: Analyze echo -n "Line3" >> file.txt

   This appends "Line3" without newline to file.txt.

4. Final Answer:

   Line1\nLine2\nLine3 -> Option D

5. Quick Check:

   echo adds newline, printf adds newline, echo -n no newline = D [OK]

Hint: Remember echo -n skips newline, printf needs explicit \n [OK]

Common Mistakes:

• Assuming echo -n adds newline
• Forgetting printf needs \n
• Confusing overwrite (>) and append (>>)

4. The following script is intended to write two lines to output.txt but only writes one line. What is the error?

echo "First line" > output.txt
printf "Second line" > output.txt

medium

A. printf needs \n to add newline

B. Second command overwrites the file instead of appending

C. echo should use >> to append

D. Missing quotes around Second line

Solution

1. Step 1: Check file redirection operators

   The first command uses > which creates or overwrites output.txt with "First line".

2. Step 2: Check second command redirection

   The second command also uses > which overwrites output.txt, replacing previous content.

3. Step 3: Correct approach

   To keep both lines, second command should use >> to append instead of overwrite.

4. Final Answer:

   Second command overwrites the file instead of appending -> Option B

5. Quick Check:

   Using > twice overwrites file = D [OK]

Hint: Use >> to append, > overwrites file [OK]

Common Mistakes:

• Thinking \n missing causes no second line
• Confusing > and >> operators
• Assuming echo always appends

5. You want to create a file report.txt with exactly two lines:
"Summary:"
"All tests passed"
Which script snippet correctly creates this file with proper newlines and no extra blank lines?

hard

A. printf "Summary:\nAll tests passed\n" > report.txt

B. echo "Summary:" > report.txt && echo "All tests passed" > report.txt

C. echo -n "Summary:\nAll tests passed" > report.txt

D. printf "Summary:" > report.txt && printf "All tests passed" >> report.txt

Solution

1. Step 1: Check echo commands in echo "Summary:" > report.txt && echo "All tests passed" > report.txt

   echo "Summary:" > report.txt && echo "All tests passed" > report.txt uses echo twice with > redirection, so the second command overwrites the first line.

2. Step 2: Check printf commands in printf "Summary:\nAll tests passed\n" > report.txt

   printf "Summary:\nAll tests passed\n" > report.txt uses printf with explicit \n for newlines, creating exactly two lines with no extra blank lines.

3. Step 3: Analyze Options C and D

   echo -n "Summary:\nAll tests passed" > report.txt uses echo -n which suppresses newlines and includes literal \n, so no actual new lines appear. printf "Summary:" > report.txt && printf "All tests passed" >> report.txt uses printf without \n, so lines run together.

4. Final Answer:

   printf "Summary:\nAll tests passed\n" > report.txt -> Option A

5. Quick Check:

   printf with explicit \n creates exact lines = B [OK]

Hint: Use printf with \n for precise multi-line output [OK]

Common Mistakes:

• Using echo -n with \n prints literal \n
• Forgetting \n in printf causes no new lines
• Using > and >> inconsistently