User ID: mio
Subject: Extract .DMG on GNU/Linux

Simple steps to extract a .dmg on GNU/Linux.
For the example on this page, we're going to use the SFMono.dmg font available on Apple's design website. 

wget "https://devimages-cdn.apple.com/design/resources/download/SF-Mono.dmg"
7z x SF-Mono.dmg
cd SFMonoFonts
7z x "SF Mono Fonts.pkg"
7z x Payload~

Installing the Fonts

As a bonus: installing the fonts we just downloaded!

  1. Navigate to the font files 
    cd Library/Font
  2. Copy the font files to a system directory (note that this may be different on your distribution) 
    sudo cp ./*.otf /usr/share/fonts/opentype
  3. Re-build the font cache information 
    sudo fc-cache -f