A ruby CLI program to manage tasks

tasks.rb

File.open("text.txt", "a+") do |f|
  f.seek(0)
  tasks = f.lines.to_a
  tasks.delete_at(ARGV[1].to_i) if ARGV[0] == "d" and !ARGV[1].nil? and ARGV[1].to_i
  tasks << ARGV.join(" ") unless ARGV[0] == "d" or ARGV.empty?
  File.open("text.txt", "w") {|g| g.puts tasks; tasks.each_with_index {|t, i| puts "#{i}: #{t}"} }
end