MacOS Monterey compatible Mac for downloading and installing the macOS 12 beta onto.This is it, you have a bootable OS X usb drive.This tutorial will walk through the steps to create a bootable macOS Monterey beta boot drive for both the developer beta and public beta.īe sure you have the following before getting started: From the first iso, obtained on step 3, copy BaseSystem.chunklist and BaseSystem.dmg on the thumb drive (actually, the latter might not be necessary - but it worked for me at this step and I stopped experimenting).

Mount the thumb drive (you might need to apt-get install hfsprogs to mount an HFS filesystem). In my case (High Sierra 10.13.6), 4Gb stick was sufficient, even though createinstallmedia requires 8Gb. iso as well ( dmg2iso -i BaseSystem.dmg -o BaseSystem.iso)Ĭopy it to a thumb drive: dd if=BaseSystem.iso of=/dev/sdX BS=1M. iso įind BaseSystem.dmg in the mounted image. You can do it from GUI (right click, 'Open with disk image mounter') or something like mount -o loop. So, you'll need to find an alternative source.Ĭonvert. This question on apple support has all the links, but they are only accessible from OS X (if you had access to a live OS X at this point - you probably would've just used createinstallmedia already, right?).

Unlike El Capitan, High Sierra only needs BaseSystem.dmg, which also has enough free space to boot - so, the process overall can be simplified a bit. So, leaving it here in case somebody else will need to.

I recently had to make a High Sierra 10.13.6 bootable USB drive, and the process turned out a bit more involved that just dd-ing the dmg2img-generated ISO to a thumb drive.

Create mac os usb installer