Style guide and conventions in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a comment in a 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 -- which are not valid comment symbols in Bash.

Forgetting to add the comment symbol at the start.

In Bash scripts, comments start with the # symbol.

2fill in blank

medium

Complete the code to declare a variable named 'name' with value 'Alice'.

Bash Scripting

[1]=Alice

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

Aname

Bdeclare name

Clet name

Dvar name

Attempts:

3 left

💡 Hint

Common Mistakes

Adding spaces around the equal sign.

Using keywords like var or let which are not used in Bash.

In Bash, variables are assigned without spaces and without keywords like var or let.

3fill in blank

hard

Fix the error in the code to print the variable 'name' value.

Bash Scripting

echo [1]

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

A$name

Bname

C"name"

D'name'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the $ sign before the variable name.

Using quotes that prevent variable expansion.

To print a variable's value in Bash, prefix it with $.

4fill in blank

hard

Fill both blanks to write a for loop that prints numbers 1 to 3.

Bash Scripting

for [1] in [2]
do
  echo $[1]
done

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

Ai

B1 2 3

Cseq 1 3

Dnum

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'seq 1 3' without command substitution.

Using invalid variable names.

The loop variable is 'i' and the list is '1 2 3' to iterate over numbers 1 to 3.

5fill in blank

hard

Fill all three blanks to create an if statement that checks if variable 'count' is greater than 10.

Bash Scripting

if [ [1] [2] [3] ]
then
  echo "Count is large"
fi

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

A$count

B>

C10

D-gt

Attempts:

3 left

💡 Hint

Common Mistakes

Using > instead of -gt inside [ ] which causes errors.

Not using $ before the variable name.

In Bash, numeric comparison uses -gt inside [ ]. The variable is referenced with $.

Practice

1. Which of the following is the best practice for naming variables in a bash script according to style guides?

easy

A. Use clear, lowercase names with underscores, like file_count

B. Use uppercase names with spaces, like FILE COUNT

C. Use mixed case without underscores, like FileCount

D. Use numbers only, like 123

Solution

1. Step 1: Understand variable naming conventions

   Bash style guides recommend clear, lowercase variable names with underscores for readability.

2. Step 2: Compare options

   Use clear, lowercase names with underscores, like file_count uses lowercase and underscores, which is clear and readable. Other options use spaces, uppercase, or numbers only, which are not recommended.

3. Final Answer:

   Use clear, lowercase names with underscores, like file_count -> Option A

4. Quick Check:

   Variable naming = lowercase_with_underscores [OK]

Hint: Pick lowercase with underscores for variable names [OK]

Common Mistakes:

• Using uppercase or spaces in variable names
• Using camelCase instead of underscores
• Using numbers only as variable names

2. Which of the following is the correct way to add a comment in a bash script?

easy

A. # This is a comment

B. /* This is a comment */

C. // This is a comment

D.

Solution

1. Step 1: Identify bash comment syntax

   Bash uses the # symbol to start a comment line.

2. Step 2: Check each option

   # This is a comment uses #, which is correct. Options B, C, and D use comment styles from other languages.

3. Final Answer:

   # This is a comment -> Option A

4. Quick Check:

   Comment start = # [OK]

Hint: Use # to start comments in bash scripts [OK]

Common Mistakes:

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

3. What will be the output of the following bash script snippet?

count=3
if [ $count -gt 0 ]; then
  echo "Count is positive"
fi

medium

A. No output

B. Syntax error

C. Count is positive

D. Count is zero

Solution

1. Step 1: Evaluate the condition

   The variable count is 3, which is greater than 0, so the condition [ $count -gt 0 ] is true.

2. Step 2: Determine the output

   Since the condition is true, the script executes echo "Count is positive", printing that line.

3. Final Answer:

   Count is positive -> Option C

4. Quick Check:

   3 > 0 prints message [OK]

Hint: If condition true, echo runs; else no output [OK]

Common Mistakes:

• Confusing syntax causing errors
• Assuming no output if condition true
• Misreading the comparison operator

4. Identify the error in this bash script snippet:

for i in 1 2 3
 do
 echo $i
 done

medium

A. Missing semicolon after 3

B. Incorrect indentation of echo

C. Missing do keyword

D. No error, script runs correctly

Solution

1. Step 1: Check for syntax correctness

   The for loop syntax is correct: for i in 1 2 3; do ... done. The newline before do is allowed.

2. Step 2: Verify indentation and keywords

   Indentation is recommended but not required. The do keyword is present. No semicolon needed before newline.

3. Final Answer:

   No error, script runs correctly -> Option D

4. Quick Check:

   Newline before do is valid [OK]

Hint: Newline before do is allowed; indentation is style only [OK]

Common Mistakes:

• Thinking semicolon is mandatory before newline
• Confusing indentation with syntax error
• Missing do keyword

5. You want to write a bash script that reads a filename from the user, checks if it exists, and prints a message. Which style guide practice should you follow to make your script clear and maintainable?

hard

A. Use uppercase variable names and no comments

B. Use clear lowercase variable names with underscores and add comments explaining steps

C. Write all code in one line without indentation

D. Avoid using comments and use single-letter variable names

Solution

1. Step 1: Recall style guide recommendations

   Good style means using clear, lowercase variable names with underscores and adding comments to explain the script.

2. Step 2: Evaluate options

   Use clear lowercase variable names with underscores and add comments explaining steps follows these practices. Other options use uppercase, no comments, poor formatting, or unclear names, which reduce clarity.

3. Final Answer:

   Use clear lowercase variable names with underscores and add comments explaining steps -> Option B

4. Quick Check:

   Clear names + comments = maintainable script [OK]

Hint: Use clear names and comments for readable scripts [OK]

Common Mistakes:

• Skipping comments thinking code is self-explanatory
• Using uppercase or single-letter variables
• Writing code without indentation