All tests passing on Windows (if you have 'file.exe' installed).

lib/paperclip/thumbnail.rb

@@ -71,8 +71,8 @@ module Paperclip
     def transformation_command
       scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
       trans = []
-      trans << "-resize" << "'#{scale}'" unless scale.nil? || scale.empty?
-      trans << "-crop" << "'#{crop}'" << "+repage" if crop
+      trans << "-resize" << %["#{scale}"] unless scale.nil? || scale.empty?
+      trans << "-crop" << %["#{crop}"] << "+repage" if crop
       trans
     end
   end

lib/paperclip/upfile.rb

@@ -17,7 +17,7 @@ module Paperclip
       when "csv", "xml", "css"       then "text/#{type}"
       else
         # On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
-        content_type = (Paperclip.run("file", "--mime-type :file", :file => self.path).split(':').last.strip rescue "application/x-#{type}")
+        content_type = (Paperclip.run("file", "-b --mime-type :file", :file => self.path).split(':').last.strip rescue "application/x-#{type}")
         content_type = "application/x-#{type}" if content_type.match(/\(.*?\)/)
         content_type
       end

test/paperclip_test.rb

@@ -11,19 +11,19 @@ class PaperclipTest < Test::Unit::TestCase
     should "execute the right command with :image_magick_path" do
       Paperclip.options[:image_magick_path] = "/usr/bin"
       Paperclip.expects(:log).with(includes('[DEPRECATION]'))
-      Paperclip.expects(:log).with("/usr/bin/convert 'one.jpg' 'two.jpg'")
-      Paperclip::CommandLine.expects(:"`").with("/usr/bin/convert 'one.jpg' 'two.jpg'")
+      Paperclip.expects(:log).with(regexp_matches(%r{/usr/bin/convert ['"]one.jpg['"] ['"]two.jpg['"]}))
+      Paperclip::CommandLine.expects(:"`").with(regexp_matches(%r{/usr/bin/convert ['"]one.jpg['"] ['"]two.jpg['"]}))
       Paperclip.run("convert", ":one :two", :one => "one.jpg", :two => "two.jpg")
     end
 
     should "execute the right command with :command_path" do
       Paperclip.options[:command_path] = "/usr/bin"
-      Paperclip::CommandLine.expects(:"`").with("/usr/bin/convert 'one.jpg' 'two.jpg'")
+      Paperclip::CommandLine.expects(:"`").with(regexp_matches(%r{/usr/bin/convert ['"]one.jpg['"] ['"]two.jpg['"]}))
       Paperclip.run("convert", ":one :two", :one => "one.jpg", :two => "two.jpg")
     end
 
     should "execute the right command with no path" do
-      Paperclip::CommandLine.expects(:"`").with("convert 'one.jpg' 'two.jpg'")
+      Paperclip::CommandLine.expects(:"`").with(regexp_matches(%r{convert ['"]one.jpg['"] ['"]two.jpg['"]}))
       Paperclip.run("convert", ":one :two", :one => "one.jpg", :two => "two.jpg")
     end
 

test/thumbnail_test.rb

@@ -92,7 +92,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "send the right command to convert when sent #make" do
         Paperclip::CommandLine.expects(:"`").with do |arg|
-          arg.match %r{convert '#{File.expand_path(@thumb.file.path)}\[0\]' -resize 'x50' -crop '100x50\+114\+0' \+repage '.*?'}
+          arg.match %r{convert ["']#{File.expand_path(@thumb.file.path)}\[0\]["'] -resize ["']x50["'] -crop ["']100x50\+114\+0["'] \+repage ["'].*?["']}
         end
         @thumb.make
       end
@@ -116,7 +116,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "send the right command to convert when sent #make" do
         Paperclip::CommandLine.expects(:"`").with do |arg|
-          arg.match %r{convert -strip '#{File.expand_path(@thumb.file.path)}\[0\]' -resize 'x50' -crop '100x50\+114\+0' \+repage '.*?'}
+          arg.match %r{convert -strip ["']#{File.expand_path(@thumb.file.path)}\[0\]["'] -resize ["']x50["'] -crop ["']100x50\+114\+0["'] \+repage ["'].*?["']}
         end
         @thumb.make
       end
@@ -154,7 +154,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "send the right command to convert when sent #make" do
         Paperclip::CommandLine.expects(:"`").with do |arg|
-          arg.match %r{convert '#{File.expand_path(@thumb.file.path)}\[0\]' -resize 'x50' -crop '100x50\+114\+0' \+repage -strip -depth 8 '.*?'}
+          arg.match %r{convert ["']#{File.expand_path(@thumb.file.path)}\[0\]["'] -resize ["']x50["'] -crop ["']100x50\+114\+0["'] \+repage -strip -depth 8 ["'].*?["']}
         end
         @thumb.make
       end