Style guide and conventions in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

Why should you use comments in bash scripts?

Comments explain what the script or parts of it do. They help others and your future self understand the code easily.

beginner

What is the recommended way to name variables in bash scripts?

Use uppercase letters with underscores, like MY_VARIABLE. This makes variables easy to spot and avoids conflicts with system variables.

intermediate

Why should you use double quotes around variables in bash scripts?

Double quotes prevent word splitting and globbing, which can cause unexpected behavior when variables contain spaces or special characters.

intermediate

What is the purpose of using 'set -e' at the start of a bash script?

'set -e' makes the script stop immediately if any command fails. This helps catch errors early and avoid running wrong commands.

beginner

How should you format your bash script for readability?

Use indentation for blocks like loops and conditionals, add blank lines between sections, and keep lines short. This makes the script easier to read and maintain.

What is the best way to name variables in bash scripts?

A Numbers only (e.g., 123)

B Lowercase letters without underscores (e.g., myvar)

C Mixed case with spaces (e.g., My Var)

D Uppercase letters with underscores (e.g., MY_VAR)

Uppercase letters with underscores are the standard for bash variables to improve readability and avoid conflicts.

Why should you put double quotes around variables in bash scripts?

A To comment out the variable

B To make variables bold

C To prevent word splitting and globbing

D To convert variables to uppercase

Double quotes protect variables from splitting into multiple words or matching filenames unexpectedly.

What does 'set -e' do in a bash script?

A Stops the script if any command fails

B Enables verbose output

C Ignores all errors

D Runs the script in the background

'set -e' makes the script exit immediately on any error, helping catch problems early.

Which of these is a good practice for bash script readability?

A Use random variable names

B Use indentation and blank lines

C Avoid comments

D Write all code in one long line

Indentation and blank lines make scripts easier to read and understand.

Why add comments in your bash scripts?

A To explain what the code does

B To make the script run faster

C To hide code from the shell

D To change variable names

Comments help others and yourself understand the purpose and function of the code.

Explain three key style guide rules you should follow when writing bash scripts.

Think about naming, quoting, and documentation.

Describe how formatting and error handling improve bash script quality.

Consider readability and safety.

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