1:1 back up USB Flash Drive Yosemite installer data to IMG in OS X,like ghost works in Windows

[liujianwei]

I have one 32GB USB Flash Drive,it content 6GB  Yosemite installer data.I wanna create a IMG file(dd can do this,but I want IMG file not bigger than 6GB,dd create 32GB file),then format USB Flash Drive to carry some movie to another computer,after that I use dd to restore IMG to USB Flash Drive,get 100% same USB Flash Drive before format.Just like ghost works in Windows,how can I do this?

Seems like I can dd copies by using the count parameter. Look at the end sector for the 2nd partition, and use bs=<sector size> and count=<end

But can anybody give me a example.here is my USB Flash Drive fdisk output

Disk: /dev/rdisk2 geometry: 3892/255/63 [62537728 sectors]

Signature: 0xAA55

         Starting       Ending

 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]

------------------------------------------------------------------------

 1: EE 1023 254  63 - 1023 254  63 [         1 -     409639] <Unknown ID>

 2: AF 1023 254  63 - 1023 254  63 [    409640 -   11718752] HFS+        

 3: 0B 1023 254  63 - 1023 254  63 [  12390536 -   49885008] Win95 FAT-32

 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused 

[mjames21]

Use SuperDuper. It does what you describe and it has a free trial.  I don't think the trial expires, but if you use it and it works for you please purchase, it's only $27.99  

 

http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html