count the size of all files in the directory

countsize.rb

#!/usr/bin/ruby

ttlsize = 0.0
curdir = ""
if !!ARGV[0]
        curdir = ARGV[0] + "/*"
else
        curdir = "*"
end
Dir[curdir].each do |x|
        ttlsize += (File.stat(x).size/1024.to_f).to_s[/.*\.../].to_f
end
puts ttlsize.to_s << " MB"