74 responses

  1. Theo Douglas
    June 5, 2015

    This is good I used to use dd all the time and still do in some occasions, but, I have found two better solutions which are easier for the average Mac Joe too.

    WINDOWS: For making a bootable Windows installer from OS X I’ve found the absolute easiest method is to use Boot Camp Assistant, works every time and you can feed it an ISO and you’re good to go. It even works with the Preview versions too


    LINUX: For making Linux installers from ISO files, I like unetbootin, which can streamline the process of downloading the ISO of your choosing and burning it to the destination of choice for an installer.


    STORAGE & MULTI-BOOT: You can triple boot OS X, Windows, Linux, just be sure you have a big hard drive. Windows 10 is very storage hungry I wouldn’t attempt less than 50GB for Windows, you can get away with less for Linux. Best used on a 512GB+ SSD, overall.

    • Pablo
      June 5, 2015

      Great information, thanks! Trying out unetbootin now.

    • PJSF
      June 9, 2015

      Is there a link with addtional detail on using Boot Camp Assistant to create the bootable USB for Windows?

      • Paul
        June 9, 2015

        It’s quite easy, you’ll need a Windows 8 or newer ISO (windows 10 works fine), and a large enough USB key to support the file size, I’ve used a 16GB for Windows 10 and it was fine. Then open “Boot Camp Assistant” in OS X (/Applications/Utilities/ folder) and go through the steps, Apple makes it very automated and it works quite well. We’ll cover it in detail perhaps in a future walkthrough.

      • mlnotes
        January 31, 2016

        Great tool, thanks for information!

    • xDisruptor
      February 6, 2016

      > For making a bootable Windows installer from OS X I’ve found the absolute easiest method is to use Boot Camp Assistant, *works every time*

      Yeah right … unless it doesn’t even show the option to create a bootable usb thumbdrive EVEN AFTER ONE MANAGES TO MANUALLY EDIT THE .PLIST FILE. Stupid utility.

      • Steve
        March 6, 2016

        Agreed – Boot Camp Assistant is way too inflexible, wants a very rigid workflow, and gives no diagnostics, logging, progress indicators or debug options. It has a bunch of platform-specific capabilities that are hidden but strictly enforced, requiring PRAM resets to fix and .plist edits to workaround.

        It also has virtually no built-in Help or tutorial, instead shuttling you off to articles on Apple’s site that may or may not apply to the version you’re using.

    • Jonathan
      March 17, 2017

      bs=1m is the block size, if you get an error you can use bs=1M. with a capital M, you are able to see the progress by hitting ctrl+t, this will show how many blocks have passed, blocks being 1mb in size it’s easy to see.


    • Maurice
      June 5, 2017

      Theo – you saved me here! Great tip about Bootcamp Assistant

    • alxcancado
      August 15, 2017


    • David
      September 27, 2017

      unetbootin doesn’t always work, and so I would say that dd can be easier since you don’t have to create multiple bootable USBs before you get one that works. Yesterday I was trying to use a bootable Ubuntu disk to remove partitions on drives in one of the servers that I work on for work, and unetbootin created bootable USBs wouldn’t work in the servers. However, the dd created bootable USBs worked just fine.

      • Gavin
        October 27, 2017

        I used unebootin and found not all files loaded, does not work all the time, and created endless frustration and many hours. It seems for no issues dd is the only way to be certain of success. Would not load gnome through unebootin

  2. Barton
    June 5, 2015

    > The ‘bs=1m’ at the end is for bitesize
    I would suggest “block size”. It is the size of the chunks of data that are written, in bytes.

  3. HenryAZ
    June 5, 2015

    Can you explain the significance of the ‘r’ in front of the disk identifier?

    • Paul
      June 5, 2015

      The ‘r’ is for ‘raw’, basically it’s faster and more direct than just using the disk identifier. You can use either, or one or the other, as far as I know there’s no benefit other than speed.

      Cholingo details this quite a bit below, referencing the man page for hdiutil, thanks for that!

  4. Cholingo
    June 5, 2015

    The ‘r’ prefixing the identifier signifies the raw data under the visible file system, which is necessary to make the output volume bootable. It’s also faster because it’s block aligned IO. Basically, rdisk goes directly to the disk, disk goes through the fileystem.

    man hdiutil has more details if you’re curious which has this

    ” Since any /dev entry can be treated as a raw disk image, it is worth noting which devices can be accessed when and how. /dev/rdisk nodes are character-special devices, but are “raw” in the BSD sense and force block-aligned I/O. They are closer to the physical disk than the buffer cache. /dev/disk nodes, on the other hand, are buffered block-special devices and are used primarily by the kernel’s filesystem code.

    It is not possible to read from a /dev/disk node while a filesystem is mounted from it, but anyone with read access to the appropriate /dev/rdisk node can use hdiutil verbs such as fsid or pmap with it.Beware that information read from a raw device while a filesystem is mounted may not be consistent because the consistent data is stored in memory or in the filesystem’s journal.”

  5. Justin
    August 20, 2015

    THis is great. Seems so simple that I am suprised there isnt a simple GUI app for mac to do this behind the scenes. Wouldnt this implementation be trivial?

  6. brandito
    August 22, 2015

    how do i know when it is finished? It has been a few hours, but the flash drive is still blinking and after entering the password, i never received a complete message. .iso is about 4.8GB SUSE Linux.

    • Itan
      August 22, 2015

      When dd is complete you will be returned to the command prompt, if the disk is still blinking (writing) it has not finished yet. Depends on the speed of the drive, and other things really, but it can take a while to burn an ISO to a a usb flash disk.

    • Michael
      December 9, 2015

      If you press ^T in the terminal, it will send a SIGINFO signal to dd which will print out the current progress.

      • K.S.
        January 19, 2016

        Great tip! This should be added to the article.

      • peyman
        February 18, 2016

        it’s a great tip thank you :)

  7. Ehsan
    August 23, 2015

    It is a really feasible solution. Thanks a lot.

  8. superfuji
    September 7, 2015

    I have followed the above procedure but I always fail.

    What I have done is create a partition first on the usb using “free space” then execute the sudo dd command (same as the above instruction) on the usb primary drive (disk2 in my case).

    • Mark
      June 26, 2016

      Yes, I found that using the disk name + partition in the dd command (eg, disk2s2) is not creating a bootable drive that will work on the intended PC-The dd does complete ok though. Tonight I am going to try just referencing the primary disk identifier (eg disk2) to see what happens.

  9. Marco Garcês
    September 17, 2015

    Just a suggestion using dd; you can send a SIGINFO to dd, to find out the progress; the best way is to press “ctrl + t” and dd will display the current progress.

    • Michael
      November 9, 2015

      Great advice, thanks!

  10. Starting Grid
    September 30, 2015

    Have done all of that but than I can not enter my password.
    thx for help.

  11. Mike
    October 6, 2015

    This did not work for me on 10.10.5 (2012 Mac mini). I tried every variation I could think of:

    – Partitioning the USB drive as GUID, MBR
    – Formatting as “Free Space,” HFS+, ExFAT, FAT
    – dd to diskn, rdiskn, disknsm, rdisknsm

    Nothing worked. Some combinations produced a drive that contained the files from the iso, but it wouldn’t boot (did not show up in EFI when holding down Option, nor in System Preferences / Startup Disk). Others were unreadable altogether.

    Good thing I have an external Blu-ray drive. I managed to dig up an old blank CD and burn it. Booted just fine. Who says optical media is dead??

    • Dave
      December 16, 2015

      Here is the correct way to burn a usb with diskutil. This article left out that the .iso needs to be converted to an .img an apple puts on at the end a .dmg (it’s an apple thingy). OS X 10.11.2


      hdiutil convert -format UDRW -o filename.iso (backspace and change to .img) filename.iso

      Here is how it looks, (copy and paste filename)
      hdutil convert -format UDRW -o ubuntu-15.10-desktop-amd64.img ubuntu-15.10-desktop-amd64.iso

      Instead of typing in ~/home/usr/ an so on when in the terminal cd to working directory or where you downloaded the iso file then the command for dd if=filename.iso of=/dev/rdiskn (where n is the number) bs=1m.

      In apple’s dd if=filename.img.dmg of=/dev/rdiskn bs=1m

      Hope this helps

      • Paul
        January 10, 2016

        Now THIS was helpful! Totally the missing info from the article. Brain-racking, hours-Googling problem, grumble mood thanks!

      • Jeff
        August 1, 2016

        I also needed this step. My commands were:
        diskutil unmountDisk /dev/disk2s1
        sudo dd if=~/Desktop/lubuntu-16.04-desktop-i386.img.dmg of=/dev/rdisk2 bs=1m

  12. flux
    November 6, 2015

    didn’t work usb was not bootable

    • wrong
      November 6, 2015

      You burned the ISO wrong, try again

      • rob
        November 18, 2015

        Doesn’t work for me either. I tried 3 different thumb drives, and downloaded both the official Windows 10 ISO direct from Microsoft, and tried a pirated ISO. I also tried converting both of the ISO’s to images as well. Neither will boot in my PC, in any of the 3 thumb drives, using the ISO or the IMG.

        I also used the same drives and the same method to create two different bootable Linux drives, which both work fine. So the process is obviously correct, but there has to some other variable here.

        For the purposes of thoroughness, I tried 1 Sandisk, 2 PNY, and 1 ADATA drives.

  13. Alex
    November 12, 2015

    Didn’t work for me ether. The thumb drive after that is empty and not formatted even though it says the transfer was successful.

    3830+1 records in
    3830+1 records out
    4017000448 bytes transferred in 1102.431775 secs (3643763 bytes/sec)

    But then when you reinsert the usb thumb drive OS says “The disk you inserted was not readable by this computer.” and offers to initialize it.

    • Same
      January 26, 2016

      I have the exact same problem! Someone please help!

  14. Alex
    November 12, 2015

    Looks like you have to convert the iso into img first.

  15. Ely
    November 13, 2015

    Something else to add that makes the process easier; dragging the source .iso file to your terminal window will input the file path for you.

  16. efe
    November 14, 2015

    I have a PC and a Mac. As always, my windows has crashed. So, I bought a lower version of windows and downloaded it on my Mac but the problem is I can’t create bootable USB from my PC because windows won’t start. Can I create a bootable USB from my Mac for my PC using this method?

  17. Wes Fok
    November 15, 2015

    seems working
    MACs-iMac:~ mac$ sudo dd if=/Users/mac/Downloads/CentOS-7-x86_64-Everything-1503-01.iso of=/dev/rdisk1s1 bs=1m
    7240+0 records in
    7240+0 records out
    7591690240 bytes transferred in 474.486823 secs (15999792 bytes/sec)
    MACs-iMac:~ mac$

  18. Sur Max
    January 20, 2016

    Thanks for the wonderful tip.

  19. Florian
    January 29, 2016

    Thanks! The best tutorial that I found…100% working for me

  20. Wonder
    February 11, 2016

    I am trying out using an external Harddisk to install Win8 on Mac, all the steps above appeared to work during the process, however Mac cannot detect the bootable drive.

    can the bootable disk be mounted again? Seems like it doesn’t work for me and is it required to reformat before trying again?


  21. Tom Hallam
    February 25, 2016

    Could not get this to work. I suspect that your use of a partition device (/dev/rdisk1s1) instead of the disk device (/dev/rdisk1) is the issue, as you are using disk images not partition images.

    The instructions at http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx do work

    • tres perros
      March 20, 2016

      hdiutil convert -format UDRW -o ~/path/to/target.img ~/path/to/ubuntu.iso

      diskutil list

      (determine the device node assigned to your flash media (e.g. /dev/disk2))

      diskutil unmountDisk /dev/diskN

      sudo dd if=/path/to/downloaded.img of=/dev/rdiskN bs=1m

      diskutil eject /dev/diskN

      • Cob
        August 1, 2016

        Works. You’re awesome.

  22. Gosh
    February 27, 2016

    I try “sudo umount /dev/…”, but get only “Resource busy — try ‘diskutil unmount'”. How fix this?

    • Carlos Fonseca
      March 1, 2016

      sudo diskutil unmount /dev/diskX

  23. Mr. Peabody
    March 26, 2016

    please keep this discussion alive… I have tried everything several times over, double checked, triple checked, quadruple checked all of my work and my USB drive still comes up as unreadable. I am using a Mac mini late 2011, OS 10.11.x. i’m assuming that the disk should be readable after it’s formatted and before I reboot, is that correct?

    • eva
      March 25, 2017

      I’m having the same problem :( Did you solve it?

  24. Mr. Peabody
    March 26, 2016

    i’m also assuming that, after I convert the iso to an .img.dmg file, that I am to then manually change the file name to delete the .dmg portion of the suffix, is that correct?

  25. Evan P
    April 4, 2016

    I think I may have screwed this up I used the sudo dd but totally forgot to direct it to my USB is there anyway I may have screwed up something on my drive?

  26. Ziga
    April 9, 2016

    There is progress with dd. You should use signal USR1 and kill the procecss with it. Then it will should you stats in terminal where dd runs. Ex: kill -USR1 12345
    12345 is process id from Ex: ps aux | grep dd

  27. Nico
    July 6, 2016

    Hi There, thank’s for the tutorial
    I got a problem after it
    I finished it and when i tried to reboot I got the white screen of the death and the circle with the diagonal bar.
    Even if I try to boot the recovery mode or anything
    In the single user mode it’s tell me that he can’t find a bootable partition but when I check my drive it’s telling me that it’s fine.

    I remove my Drive from it’s case and try to plug to another computer and it’s correct, everything is in it
    I have a Time Machine Backup on my other hard drive.

    Macbookpro unibody Late2011, Elcapitan, intel i5,Samsung SSD840 evo, HDD Seagate 500go

    I run out of Ideas if you guys could help me

  28. RobertG
    July 7, 2016

    I followed the directions. When I tried to boot the computer from the external device, it says “Missing operating system”

  29. Laura
    August 24, 2016

    I couldn’t get umount to work, but the alternative worked. (diskutil unmount /dev/IDENTIFIER)

    Lauras-MBP:~ laura$ sudo umount /dev/disk2s1

    WARNING: Improper use of the sudo command could lead to data loss
    or the deletion of important system files. Please double-check your
    typing when using sudo. Type “man sudo” for more information.

    To proceed, enter your password, or type Ctrl-C to abort.

    umount(/Volumes/USB): Resource busy — try ‘diskutil unmount’
    Lauras-MBP:~ laura$ diskutil unmount /dev/disk2s1
    Volume USB on disk2s1 unmounted

  30. Stanley
    September 14, 2016

    So… I messed up big time

  31. junebeetle
    September 20, 2016

    Thanks, I haven’t seen a detailed tutorial like this.

    I think sometimes disk images can be compressed or have headers, which is why this doesn’t always work. I usually mount the disk image and then “diskutil list” to find the mounted disk image and the target disk, then I “sudo dd if=/dev/DISKIMAGE of=/dev/TARGET bs=1m” and it 90% works.

  32. Chubbs 215
    October 27, 2016

    I’m a PC guy and had the problem of downloading .iso files to my MAC and unable to xfer them to my USB drive for load in my PC. HERE’S YOUR QUICK FIX!!!

    Upload the .iso to dropbox, save it onto the drive from you MAC, xfer. Peace. No TERMINAL needed.

    • Justin
      June 11, 2017

      This is not even the topic at hand. Glad your issue got solved but didn’t have anything to do with this subject.

  33. Pedro
    November 6, 2016

    I use DCFLDD (DC Forensic Lab dd) , I like it because it shows you the progress percentage and dd does not which drives me nuts

  34. Larry Rosenman
    January 26, 2017

    ctrl-t during the dd will give you how much it’s done (it sends SIGINFO)

  35. David
    March 12, 2017

    This was so simple I wonder why installers exist

    • Chris Tattersall
      May 11, 2017

      I tried this procedure as I can not upgrade my Snow Leopard to Yosemite using a DMG file downloaded from the appstore a while back (no longer available for re-download). Says it cannot be verified or my have been corrupted during download. I also have an ISO file but, after the burn to USB stick is completed (normally) using either the DMG or ISO files, I get “The disk you inserted was not readable by this computer.” Diskutil Verfy tells me that it has “Invalid B-treenode size” and Repair fails. I have tried this several times with different USB sticks and a DL CD RW and two different Macbooks (both with Snow Leopard)with same result. I eventually gave up (it’s very time consuming) and ordered a Bootable USV install Upgrade from eBay. I would like to know, however why the procedure failed in case I may need to try it again.

  36. Cicero
    May 31, 2017

    First off thank you for the tips.

    I was not able to unmount with “sudo umount”

    instead I used “sudo diskutil unmount /dev/disk4s1” in my case.

    Also much thanks to the commenter for the “control+t” command for checking the progress!

    The transfer is complete now so I’m going to check if the usb will boot.

  37. Robby robby robby bobby. ROBERT
    June 24, 2017

    There’s a unix command to pipe dd into a progress checker but I don’t remember what it is.

  38. Isaac Egglestone
    November 5, 2017

    Good old dd , I should have known this would solve my issue, thanks for the reminder, I haven’t used dd in at least 15 years.

    Except I was using in on linux to create windows boot disks back then….

    Sometimes its hard to build a better mouse trap I guess, I struggled with unetbootin, but got no love.

    Now back to basic dd and it boots fine on a dell laptop.

  39. Garret
    November 6, 2017

    I get to a point and an error comes up: /path/image.iso: No such file or directory

    • itb7
      November 27, 2017

      I have the same issue; I’ve tried typing everything in twelve ways to Sunday but have yet to get the disk image to copy onto my USB.

  40. Steve Price
    December 14, 2017

    I can not make this work on macOS High Sierra Version 10.13.2

    The instructions appear to work when I read the command line, but the thumb drive ends up empty and unformated and uninitialized.

    I tried it 3 ways:

    No bs.

    All look great on the command line, but the thumb drive gets unformatted and macOS High Sierra refuses to see it. When I plug in the drive I get this message:

    “The disk you inserted was not readable by this computer. Initialize…, Ignore, Eject

    I select Initialize and Erase the thumb drive as Mac OS (Extended (Journaled). I repeat my script and get the same bad results. I also have tried MS-DOS (FAT) and that also fails.

    /bin/ksh ~/bin/CentOS_thumb.ksh
    sudo diskutil unmount /dev/disk3s1
    Volume ThumbsUp on disk3s1 unmounted
    sudo dd if=/Users/steve/Public/Linux/CentOS/CentOS-7-aarch64-Netinstall.iso of=/dev/rdisk3s1
    load: 1.46 cmd: dd 9428 uninterruptible 1.22u 12.19s
    538348+0 records in
    538347+0 records out
    275633664 bytes transferred in 128.380321 secs (2147009 bytes/sec)
    538348+0 records in
    538347+0 records out
    275633664 bytes transferred in 128.380346 secs (2147008 bytes/sec)
    768656+0 records in
    768656+0 records out
    393551872 bytes transferred in 183.050061 secs (2149969 bytes/sec)
    sudo diskutil eject /dev/disk3s1
    Disk /dev/disk3s1 ejected
    steve@StevesiMac2017: ls -l /Users/steve/Public/Linux/CentOS/CentOS-7-aarch64-Netinstall.iso
    -rw-r–r–@ 1 steve staff 393551872 Dec 11 09:10 /Users/steve/Public/Linux/CentOS/CentOS-7-aarch64-Netinstall.iso

    • Alex
      February 13, 2018

      you should try using /dev/disk3 (or /dev/rdisk3) instead of the full volume path on the DD command – this will likely result in the volume being formatted correctly and readable under osx after its complete.

      So in your example it would be;

      sudo dd if=/Users/steve/Public/Linux/CentOS/CentOS-7-aarch64-Netinstall.iso of=/dev/rdisk3

      i had the same problem, and that was my solution which worked.

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