dmg2img software package provides Tool for converting compress dmg files to hfsplus images, you can install in your Debian 7 (Wheezy) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install dmg2img
dmg2img is installed in your system.
Make ensure the dmg2img package were installed using the commands given below,
$ sudo dpkg-query -l | grep dmg2img *
You will get with dmg2img package name, version, architecture and description in a table
| Distro | Debian 7 wheezy |
| Section | Other OSs and file systems |
| Package | dmg2img |
| Version | 1.6.2-2+b1 [amd64, armel, i386 |
| Description | Tool for converting compress dmg files to hfsplus images |
| Sub Section | otherosfs |