Mount /dev/mapper/loop1p1 /mnt/basesystemįormat the USB flash drive as HFS+: sgdisk -o /dev/sdb But writing it directly to the USB drive does not work, because that would create a partition with almost no free space and still lacking some important files.Įxtract base system image BaseSystem.dmg, convert into raw and mount too: dmg2img /mnt/installesd/BaseSystem.dmg BaseSystem.img InstallESD.dmg contains another disk image, BaseSystem.dmg, which is a bootable installer disk. Mount /dev/mapper/loop0p2 /mnt/installesd Working as a root, convert InstallESD.dmg into raw image format and mount it using kpartx: dmg2img InstallESD.dmg InstallESD.img InstallESD.dmg is an image of a GPT disk with HFS+ partition which contains installer files, but is not bootable itself.

Manually it's as mentioned in MacWorld, but using the Linux tools: While trying to image over the net, I did also try entering my iCloud credentials but would get something like 'this is not currently available' it was certainly talking online because it prompted me for multi-factor authentication.There's a ready script that automates this whole process. I did initially try using TransMac on Windows to format a USB key and restore an image to use as recovery or install media, but either the images I had were no good or the USB key never came out bootable. Insert USB in iMac and use Option + R (I think) to get the boot options, select the install media and go.

Once back in the OS, I used Apple's terminal command example to build the install media and that went flawlessly.I think I was supposed to just exit the OSX installer instead of trying to go through it. In recovery I set the startup disk back to the primary OS drive to get back in. I initially broke something because I launched the pkg file/app, thought it was going to setup USB key since I pointed it to the key, but it set the VM to boot to recovery.- From within the VM, through Safari, downloaded the El Capitan DMG.Inside VM OS: Format a USB key using disk utility, name it something simple (ex: recovery) to access later in terminal.- Used Step 5 from this page to modify the VM config so that it would properly boot.Created an OS X El Capitan VM in VirtualBox using the downloaded VMDK as the primary drive.This is an outline of how I created the install media from a Windows PC:ĭownloaded their 7-part El Capitan VMDK (virtual machine disk file)ĭownloaded VirtualBox and the Extension Pack (necessary for getting USB keys to work correctly). I was able to create proper restore media from Apple using my Windows machine and the Mac seems healthy (HDD, wired/wireless, etc.) except the screen has some light wavy bars in it. This is a 20' iMac early-2008, didn't know it was that old.

Mac os el capitan bootable usb