Question

I want to write a simple program, that writes console input to file with name i entered.

file_name = ARGV[0]
of = File.open(file_name, 'w')

while a = gets.chomp
  puts a
  of.puts a
end

# ruby write_script.rb file_name.txt

returns: main: undefined method chomp for nil:NilClass (NoMethodError)

update:

file_name = ARGV[0]
File.open(file_name, 'w') do |file|
  while (a = gets)
    print a
    file.write a
  end
end

After executing this code – program terminates at start and empty file creates.

What is the right way to do it?

Answer 1

The following code works for me :

begin
  File.open(ARGV.shift, 'w') do |f|
    while a = gets.chomp
      p a
      break if a == 'exit'
      f.puts a
    end
  end
rescue SignalException
  puts
  puts "#Completed#"
  exit
end

It should be noted that I’m using ARG.shift instead of ARG[0] because when using the latter gets will access whatever is in ARG before moving on the STDIN. ARG.shift removes the original argument.