filepath.rb

class File

	def self.actual_path(file = nil)
		file = __FILE__ if file == nil
		file = File.expand_path(file)
		if File.ftype(file) == 'link' then
			actpath = File.readlink(file)
			file = File.actual_path(actpath)
		end
		return file
	end
	
end

if $0 == __FILE__ then
	p __FILE__
	p File.expand_path(__FILE__)
	p File.actual_path(__FILE__)
end

result.txt

$ cd ~/
$ mkdir slinktest
$ cd slinktest
$ mkdir hoge
$ cd hoge
$ cp ~/filepath.rb ./
$ cd ..
$ ln -s hoge/filepath.rb ./filepath_slink.rb
$ ls -l
合計 4
lrwxrwxrwx 1 pokutuna pokutuna   16 2009-05-21 21:46 filepath_slink.rb -> hoge/filepath.rb
drwxr-xr-x 2 pokutuna pokutuna 4096 2009-05-21 21:43 hoge
$ ruby filepath_slink.rb
"filepath_slink.rb"
"/home/pokutuna/slinktest/filepath_slink.rb"
"/home/pokutuna/slinktest/hoge/filepath.rb"