From: ara.t.howard@...
Date: 2006-12-15T00:07:30+09:00
Subject: Re: Swap contents in two files

On Thu, 14 Dec 2006, Christopher Latif wrote:

> Robert Klemme wrote:
>> 2006/12/14, Christopher Latif <christopherl@bredband.net>:
>>> I have two files, I want to swap the contents of the files in my
>>> program, suggestions?
>>
>> Renaming with a third temp file name is the most efficient if you know
>> that no file handles are open on these files.
>>
>> robert
>
> How the code for that program going to look like?

   harp:~ > cat a.rb
   require 'tempfile'
   require 'fileutils'

   def swap a, b
     fu, f = FileUtils, File
     tmpdir = f.dirname b
     t = Tempfile.new f.basename(b), f.dirname(b)
     t.close
     c = t.path
     fu.mv b, c
     fu.mv a, b
     fu.mv c, a
   end

   a, b, ignored = ARGV

   swap a, b

   harp:~ > cat a
   a

   harp:~ > cat b
   b

   harp:~ > ruby a.rb a b

   harp:~ > cat a
   b

   harp:~ > cat b
   a

-a
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