The exact same code works for me with a different path.
Must be a Tilda (~) issue then.
I agree with Graham below.

-----Original Message-----
From: Graham Menhennitt [mailto:graham / menhennitt.com.au] 
Sent: Monday, October 29, 2012 10:12 AM
To: ruby-talk ML
Subject: Re: csv.rb:1342:in `initialize': No such file or directory

On 29/10/2012 19:05, Soichi Ishida wrote:
> dir  =  "~/Dropbox/Ruby/FlightLuggage/"
> file = "airport.csv"
> filename = dir + file
>
> csv_line_read = CSV.open(filename)
>
The tilde (~) expansion to the home directory name is a feature provided by the shell. The operating system knows nothing about tilde. You'll need something like ENV["HOME"]+"/Dropbox/Ruby/FlightLuggage" instead.

Graham