Ruby command line program that saves and updates users/preferences - ruby

Question

I'm building an application that takes in stdin to save a user and their preferences. Should I write the stdin to a text file and save the user input there?
commandline.rb
class CommandLine
def initialize(filename)
#file = File.open(filename, 'w')
end
def add_user(input)
#file = File.open('new_accounts.txt', 'r+')
#file.write(input)
puts input
end
def run
puts "Welcome to the Command Line Client!"
command = ''
while command != 'quit'
printf "enter command: "
input = gets.chomp
parts = input.split
command = parts[0]
case command
when 'quit' then puts 'Goodbye!'
when '-a' then add_user(parts[1..-1].join(" "))
else
puts 'Invalid command #{command}, please try again.'
end
end
end
end
a = CommandLine.new('new_accounts.txt')
a.run
Let's say I want the user to enter '-a tommy likes apples' in the command line, I want it to output:
tommy likes apples
The same user tommy could also input '-a tommy likes oranges' which would then update his previous preference:
tommy likes oranges
Any help/direction is appreciated, thanks!

Answer 1

I don't see a problem with using a text file if you are doing something simple. Alternatives are many and without more detail I'm afraid I can't make a good recommendation.
def add_user(input)
File.open('new_accounts.txt', 'w') {|file|
file.write(input)
}
puts input
end
FYI: This will make it so that your text file updates. :-)
EDIT: Changed the add_user method.