A Haskell library and command-line tool to create, inspect, and alter master boot records.
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This is a haskell library and command-line tool for inspecting, creating, and manipulating master boot records from disk images and (at your own risk!) block devices.

fdisk has a few limitations, in my humble opinion -- it's written to be used interactively, doesn't display things in machine-readable format, and seems to be mostly centered around block devices.

partly, on the other hand, explicitly favors disk images and never alters the file whose MBR you want to read.


partly view is for inspecting and dumping the contents of an MBR.

  • partly json gives you a number of ways to dump the boot record as JSON.
  • partly signature simply prints the 16-bit boot signature as four hexadecimal digits.
  • partly bootloader dumps the bootloader section (the first 446 bytes of the MBR) to a file or to stdout.
  • partly view partitions pretty-prints the partition table, à la fdisk.
  • partly view timestamp views the obsolete DOS-style disk timestamp. N.B. that there may be false positives here.
  • partly view disk-signature prints the optional disk signature used by Windows NT/2000/Vista/7 and some other things (?). N.B. that there may be false positives here, too, especially when those bytes are zeroed.

partly make is for creating MBRs, based on existing ones or not. You can see the specific flags and arguments with partly make --help.

But I really want to change the MBR of an image!

Godspeed and good luck.

partly make --from disk.img --some-options -o mbr.bin
dd if=mbr.bin of=disk.img bs=512 count=1 conv=notrunc


You should probably have GHC and cabal-install installed, firstly; your distribution (or homebrew, on OS X) probably provides these. Then cabal install partly will install the latest release from Hackage.

If you want to build from source, cabal configure and then cabal build will build it to dist/ and register it in place.

To run the tests, re-configure with cabal configure --enable-tests, cabal build, and cabal test.


  • map partition type codes to readable strings -- this is an expansive and inexact art. See this page.
  • partly view partition 1, that dumps the contents of that partition from a disk image.
  • partly make --first-partition fs.img to automagically tailor an MBR for a filesystem image.
  • Support for GUID partition tables.