Calling functions in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a simple function call

What is the output of this Bash script?

Bash Scripting

greet() {
  echo "Hello, $1!"
}
greet World

A Hello, World!

B greet World

C World

D Hello, $1!

💡 Hint

Look at how the function uses the first argument.

The function greet prints 'Hello, ' followed by the first argument passed to it, which is 'World'.

💻 Command Output

intermediate

Function with local variable scope

What will be the output of this script?

Bash Scripting

count=5
myfunc() {
  local count=10
  echo $count
}
myfunc
echo $count

A

5
5

B

5
10

C

10
10

D

10
5

💡 Hint

Remember local variables inside functions do not change outside variables.

Inside the function, count is local and set to 10. Outside, count remains 5. So the outputs are 10 then 5.

📝 Syntax

advanced

Identify the syntax error in function definition

Which option contains a syntax error in defining a Bash function?

A myfunc() { echo "Hello"; }

B myfunc() echo "Hello"

C function myfunc { echo "Hello"; }

D function myfunc() { echo "Hello"; }

💡 Hint

Check if the function body is properly enclosed.

Option B misses curly braces around the function body, causing a syntax error.

🔧 Debug

advanced

Why does this function not print the argument?

Given this script, why does it print nothing? myfunc() { echo $name } myfunc John

A The function does not use $1 to access the argument

B The function name is invalid

C The echo command is missing quotes

D The function is not called correctly

💡 Hint

How do functions access passed arguments in Bash?

In Bash, function arguments are accessed with $1, $2, etc. The variable $name is empty here.

🚀 Application

expert

Function calling another function with output capture

What is the output of this script?

Bash Scripting

get_date() {
  date +"%Y-%m-%d"
}
print_message() {
  local today=$(get_date)
  echo "Today is $today"
}
print_message

A Today is

B Today is $(get_date)

C Today is 2024-06-01

D get_date: command not found

💡 Hint

The inner function output is captured with $(...).

The function get_date returns the current date in YYYY-MM-DD format. print_message captures it and prints it.

Practice

1. In Bash scripting, how do you call a function named greet?

easy

A. Write greet() with parentheses.

B. Write call greet().

C. Just write greet on a line by itself.

D. Write run greet.

Solution

1. Step 1: Understand Bash function call syntax

   In Bash, functions are called by simply writing their name without parentheses or keywords.

2. Step 2: Compare options with Bash syntax

   Only Just write greet on a line by itself. matches the correct way: just the function name alone.

3. Final Answer:

   Just write greet on a line by itself. -> Option C

4. Quick Check:

   Function call = function name alone [OK]

Hint: Call functions by name only, no parentheses needed [OK]

Common Mistakes:

• Adding parentheses like in other languages
• Using keywords like 'call' or 'run'
• Forgetting to write the function name

2. Which of the following is the correct syntax to define a function named hello in Bash?

easy

A. hello { echo "Hi" }

B. hello() { echo "Hi" }

C. def hello() { echo "Hi" }

D. function hello() echo "Hi"

Solution

1. Step 1: Recall Bash function definition syntax

   Bash functions are defined as name() { commands; } or with the keyword function followed by name and braces.

2. Step 2: Check each option

   hello() { echo "Hi" } uses hello() { echo "Hi" }, which is correct. hello { echo "Hi" } misses the () after the name. def hello() { echo "Hi" } uses Python syntax. function hello() echo "Hi" misses braces.

3. Final Answer:

   hello() { echo "Hi" } -> Option B

4. Quick Check:

   Function syntax = name() { commands } [OK]

Hint: Use name() { commands } to define functions in Bash [OK]

Common Mistakes:

• Using Python or other language syntax
• Omitting parentheses or braces
• Misplacing the function keyword

3. What is the output of this script?

say_hello() {
  echo "Hello, $1!"
}
say_hello Alice

medium

A. Hello, Alice!

B. Hello, $1!

C. say_hello Alice

D. Error: function not found

Solution

1. Step 1: Understand function and argument usage

   The function say_hello prints "Hello," followed by the first argument $1.

2. Step 2: Identify the argument passed

   The function is called with argument "Alice", so $1 becomes "Alice".

3. Final Answer:

   Hello, Alice! -> Option A

4. Quick Check:

   Function argument $1 = Alice [OK]

Hint: Use $1 to access first argument inside function [OK]

Common Mistakes:

• Printing literal $1 instead of its value
• Forgetting to pass argument
• Misunderstanding function call syntax

4. Identify the error in this script:

greet() {
  echo "Hi $name"
}
greet John

medium

A. Function greet is not defined correctly

B. Missing semicolon after echo

C. Function call syntax is wrong

D. Variable $name is not set or passed

Solution

1. Step 1: Check variable usage inside function

   The function uses $name, but no variable named name is set or passed.

2. Step 2: Check function call and argument passing

   The function is called with "John" as argument, but the function does not use $1 to access it.

3. Final Answer:

   Variable $name is not set or passed -> Option D

4. Quick Check:

   Use $1 to access arguments, not undefined variables [OK]

Hint: Use $1 inside function to get passed arguments [OK]

Common Mistakes:

• Using undefined variables instead of $1
• Assuming arguments auto-assign to variable names
• Ignoring function call syntax correctness

5. You want to write a Bash function sum that takes two numbers as arguments and prints their sum. Which script correctly calls the function and prints the result?

hard

A. sum() {
echo $(($1 + $2))
}
sum 3 5

B. sum() {
echo $1 + $2
}
sum 3 5

C. sum() {
echo $((1 + 2))
}
sum 3 5

D. sum() {
echo $1 $2
}
sum 3 5

Solution

1. Step 1: Understand arithmetic evaluation in Bash

   To add numbers, use $((expression)). Inside, use $1 and $2 for arguments.

2. Step 2: Check each option's output

   sum() {
     echo $(($1 + $2))
   }
   sum 3 5

   correctly sums $1 + $2.

   sum() {
     echo $1 + $2
   }
   sum 3 5

   prints literal string with plus sign.

   sum() {
     echo $((1 + 2))
   }
   sum 3 5

   adds 1 and 2 literally, ignoring arguments.

   sum() {
     echo $1 $2
   }
   sum 3 5

   prints arguments separated by space.

3. Final Answer:

   sum() { echo $(($1 + $2)) } sum 3 5 -> Option A

4. Quick Check:

   Use $(( $1 + $2 )) for sum [OK]

Hint: Use $(( $1 + $2 )) to add arguments inside function [OK]

Common Mistakes:

• Printing arguments without arithmetic evaluation
• Using fixed numbers instead of arguments
• Confusing string concatenation with addition