Parse array of links and downloading them using Ruby
===

I have an array named as 'pdf_links' with links of pdf files collected by gem Mechanize.
<pre>
http://site/file1.pdf
http://site/file2.pdf
http://site/file3.pdf
http://site/file4.pdf
http://site/file5.pdf
http://site/file6.pdf
http://site/file7.pdf
</pre>

I need to save all pdf files to my didrectory.
What is the best way to do it with Ruby?
I have tried to do it with *nix string but I'm receiving an error:
pdf_links.each do |d|
system %x{ wget #{d} }
end


Please help.