Running scripts with ruby command - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a Ruby script run with ruby command

What is the output when running this Ruby script with ruby script.rb?

Ruby

puts "Hello, Ruby!"
puts 5 + 3 * 2

A Hello, Ruby!\n10

B Hello, Ruby!\n16

C Hello, Ruby!\n11

D SyntaxError

💡 Hint

Remember the order of operations in arithmetic.

The script prints the string first, then calculates 5 + (3 * 2) = 11.

❓ Predict Output

intermediate

Effect of command line argument on Ruby script output

What will be the output of this Ruby script when run as ruby greet.rb Alice?

Ruby

name = ARGV[0]
puts "Hello, #{name}!"

A NameError

B Hello, Alice!

C ARGV[0]

D Hello, !

💡 Hint

ARGV holds command line arguments passed to the script.

ARGV[0] is 'Alice', so the script prints 'Hello, Alice!'.

🔧 Debug

advanced

Identify the error when running this Ruby script

What error will occur when running this Ruby script with ruby test.rb?

Ruby

def greet(name)
  puts "Hello, #{name}!"
end

greet()

A ArgumentError: wrong number of arguments (given 0, expected 1)

B SyntaxError: unexpected end-of-input

C NoMethodError: undefined method 'greet' for main:Object

D No error, prints 'Hello, !'

💡 Hint

Check how many arguments the method expects versus what is given.

The method greet requires 1 argument but is called with none, causing ArgumentError.

❓ Predict Output

advanced

Output of a Ruby script using a block with ruby command

What is the output of this Ruby script when run with ruby block.rb?

Ruby

3.times do |i|
  puts i * 2
end

A SyntaxError

B 1\n2\n3

C 0\n1\n2

D 0\n2\n4

💡 Hint

The block variable i starts at 0 and goes up to 2.

3.times runs the block 3 times with i = 0,1,2; output is i*2 each time.

🧠 Conceptual

expert

Understanding Ruby script exit status with ruby command

If a Ruby script ends with exit(3), what will be the exit status code when run with ruby script.rb?

A 3

B nil

C 1

D 0

💡 Hint

The exit method sets the program's exit status code.

Calling exit(3) sets the exit status code to 3, which the OS receives.