Documentation with comments in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a comment in Bash script.

Bash Scripting

[1] This is a comment

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

A//

B<!--

C#

D/*

Attempts:

3 left

💡 Hint

Common Mistakes

Using // or /* for comments, which are used in other languages.

Forgetting to add the comment character at the start.

In Bash scripting, comments start with the # symbol.

2fill in blank

medium

Complete the code to add an inline comment after a command.

Bash Scripting

echo "Hello World" [1] This prints a greeting

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

A//

B#

C--

D/*

Attempts:

3 left

💡 Hint

Common Mistakes

Using // or -- which are not valid comment markers in Bash.

Placing the comment character before the command.

In Bash, inline comments start with # after the command.

3fill in blank

hard

Fix the error in the comment syntax to properly document the script.

Bash Scripting

echo "Start script" [1] This is a start message

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

A#

B//

C<!--

DREM

Attempts:

3 left

💡 Hint

Common Mistakes

Using comment styles from other languages like REM or .

Omitting the comment character entirely.

Bash uses # for comments; // and REM are invalid here.

4fill in blank

hard

Fill both blanks to add a multi-line comment using a common Bash workaround.

Bash Scripting

: [1] This is a multi-line comment
This text is ignored
[2]

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

A'

B#

C:

D"

Attempts:

3 left

💡 Hint

Common Mistakes

Using # for multi-line comments which only works for single lines.

Not quoting the text after the colon.

In Bash, multi-line comments can be simulated using a no-op command : followed by a quoted string.

5fill in blank

hard

Fill both blanks to document a function with comments.

Bash Scripting

function greet() {
  [1] "Hello, $1!"  [2] # Print greeting
}

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

A{

Becho

C#

D(

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of curly braces for function body.

Forgetting the comment character #.

Using print instead of echo.

Functions in Bash start with { and end with }, echo prints text, and # starts comments.

Practice

1. What is the main purpose of comments in a Bash script?

easy

A. To explain what the code does for better understanding

B. To make the script run faster

C. To change the output of the script

D. To store variables for later use

Solution

1. Step 1: Understand the role of comments

   Comments are lines starting with # that explain the code but do not affect execution.

2. Step 2: Identify the correct purpose

   Comments help humans understand the script, not the computer or output.

3. Final Answer:

   To explain what the code does for better understanding -> Option A

4. Quick Check:

   Comments explain code = D [OK]

Hint: Comments explain code, they don't affect running [OK]

Common Mistakes:

• Thinking comments speed up scripts
• Believing comments change output
• Confusing comments with variables

2. Which of the following is the correct way to write a comment in a Bash script?

easy

A. // This is a comment

B. # This is a comment

C.

D. /* This is a comment */

Solution

1. Step 1: Recall Bash comment syntax

   Bash comments start with the # symbol and continue to the end of the line.

2. Step 2: Match the correct syntax

   Only # This is a comment uses # correctly; others are for other languages.

3. Final Answer:

   # This is a comment -> Option B

4. Quick Check:

   Bash comments start with # = B [OK]

Hint: Bash comments always start with # [OK]

Common Mistakes:

• Using // like in JavaScript
• Using /* */ like in C
• Using HTML comment style

3. What will be the output of this script?

#!/bin/bash
# Print greeting message
echo "Hello, world!"  # This prints the message

medium

A. This prints the message

B. # Print greeting message

C. Hello, world!

D. No output

Solution

1. Step 1: Identify executable lines

   Lines starting with # are comments and ignored; only echo prints output.

2. Step 2: Determine output of echo command

   echo "Hello, world!" prints Hello, world! exactly.

3. Final Answer:

   Hello, world! -> Option C

4. Quick Check:

   Comments ignored, echo prints text = C [OK]

Hint: Only echo prints; comments do not show in output [OK]

Common Mistakes:

• Thinking comments print
• Confusing inline comments as output
• Expecting comment text to appear

4. Identify the error in this Bash script snippet:

#!/bin/bash
# This is a comment
#echo "Hello"
echo "World"

medium

A. The line '#echo "Hello"' is treated as a comment and not executed

B. The comment symbol # is missing

C. The echo command is misspelled

D. The script will print both Hello and World

Solution

1. Step 1: Analyze the commented line

   The line '#echo "Hello"' starts with #, so it is a comment and ignored.

2. Step 2: Check script output

   Only echo "World" runs, so only 'World' prints, not 'Hello'.

3. Final Answer:

   The line '#echo "Hello"' is treated as a comment and not executed -> Option A

4. Quick Check:

   Lines starting with # are comments = A [OK]

Hint: Lines starting with # are never executed [OK]

Common Mistakes:

• Thinking commented lines run
• Missing # on comment lines
• Expecting both outputs

5. You want to add a comment explaining a complex command in your Bash script. Which is the best practice?

hard

A. Add the comment without # anywhere in the script

B. Place the comment on the same line after the command using #

C. Put the comment inside double quotes after the command

D. Write the comment on the line before the command starting with #

Solution

1. Step 1: Understand comment placement

   Comments before commands clearly explain what the command does before it runs.

2. Step 2: Evaluate options

   Comments inside quotes or without # are treated as code or cause errors; inline comments are okay but less clear for complex commands.

3. Final Answer:

   Write the comment on the line before the command starting with # -> Option D

4. Quick Check:

   Comments before commands improve clarity = A [OK]

Hint: Put comments before complex commands for clarity [OK]

Common Mistakes:

• Putting comments inside quotes
• Omitting # for comments
• Adding comments after commands for complex lines