another code blog

Using dd and pv on OS X

I find myself burning ISOs to flash drives fairly often. This is the best and quickest way I've found of doing it (on OS X - your experience with other systems and non-BSD tools may differ):

$RDISK=/dev/rdisk1 # diskutil list
dd if=$FILE \
| pv -tpreb -s $(du -k $FILE | awk '{print $1}')k \
| sudo dd of=$RDISK bs=1m


  • $RDISK should have the r in front (i.e. /dev/rdisk1 not /dev/disk1), that tells the kernel not to buffer it. It will display as /dev/disk1 in diskutil list, but you should put the r in front. This makes it faster.

  • bs=1m tells dd to use a blocksize of 1m. This makes it faster.

  • $(du -k $FILE | awk '{print $1}')k is a hack to make sure that dd understands the units being shown in du's answer. We pass the -k flag to du, which asks it to display the size of the file in kilobyte blocks. The snippet then has a trailing 'k', which makes it clear that the result is in kilobytes. This just gives you a progress bar.