Convert the High Sierra installer app to an ISO - UPDATE: SUCCESS!!!

[br0adband]

Ok, in the past there have been other threads for making the installer.app file for various versions of OSX/macOS into a bootable ISO for using with VMWare or VirtualBox such as those for El Capitan then Sierra but of course as times change so does Apple and so does the installer.app which of course for High Sierra is different once again.

Now, before anyone goes off to hit that Post or Submit button and ask "Why not just make a bootable USB stick and be done with it?" I'll say if you read what I just posted above I'm not looking (and neither are other people) for a bootable USB stick or image because virtual machines won't boot those at least not that I'm aware of - that would be AWESOME to have VMware Fusion or VirtualBox or Parallels be able to boot from a USB stick like a traditional PC or Mac is capable of doing but alas, so far that aspect of booting has not been implemented for virtual machine software (again, that I know of, and I test stuff constantly).

The topic at hand is taking the Install macOS High Sierra Beta.app file (and soon enough the final release in a few days as well) that is downloaded from the App Store and then convert that to a bootable ISO file (just like we've done in the past with El Capitan, Sierra, and previous releases as well) successfully and have that work for installing the OS in VMware/VirtualBox/Parallels. So far, in my attempts, what happens by using the older instructions and scripts for Sierra that I've used before (with great success for that version of macOS) end up creating a 9GB+ file that does boot but what happens is that it ends up doing a remote install from Apple's servers and not from the ISO itself which seems a bit stupid to me.

I'm not 100% sure why it's doing that because all the files needed to install the OS are obviously contained in the installer.app file already but no matter what I do, no matter how carefully I examine the script itself, I end up each time with an ISO that does boot (that works every time, thankfully) but it will not install from the ISO and requires network access and a 5GB download every single time. I'm on a fast Internet connection and I'm nowhere near my data cap for September so I don't really care about having "wasted" almost 50GB of bandwidth on multiple attempts and it does the remote install every time, but it is somewhat frustrating to not get this working.

So, if anyone wants to take a shot at this, here's the script I've used to create the bootable ISO (again, it IS bootable) but it then simply reverts to the remote install routine - I'm trying to get things done from the contents of the ISO (which was created from the installer.app so all the files are actually there and should not require nor actually use the remote installer BS. The filename I chose was highsierra_iso.sh and saved to the Desktop then chmod +x for making it executable as usual. Note that when High Sierra is finalized and released the installer will just drop the word "Beta" from the name of the installer.app so, that should be the only change after it's released.

# Generate a BaseSystem.dmg with 10.13 Install Packages
hdiutil attach /Applications/Install\ macOS\ High\ Sierra\ Beta.app/Contents/SharedSupport/InstallESD.dmg -noverify -mountpoint /Volumes/highsierra
hdiutil create -o /tmp/HighSierraBase.cdr -size 7316m -layout SPUD -fs HFS+J
hdiutil attach /tmp/HighSierraBase.cdr.dmg -noverify -mountpoint /Volumes/install_build
asr restore -source /Applications/Install\ macOS\ High\ Sierra\ Beta.app/Contents/SharedSupport/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase
cp -R /Volumes/highsierra/Packages /Volumes/OS\ X\ Base\ System/System/Installation
hdiutil detach /Volumes/OS\ X\ Base\ System/
hdiutil detach /Volumes/highsierra/
mv /tmp/HighSierraBase.cdr.dmg /tmp/BaseSystem.dmg

# Restore the 10.13 Installer's BaseSystem.dmg into file system and place custom BaseSystem.dmg into the root
hdiutil create -o /tmp/HighSierra.cdr -size 8965m -layout SPUD -fs HFS+J
hdiutil attach /tmp/HighSierra.cdr.dmg -noverify -mountpoint /Volumes/install_build
asr restore -source /Applications/Install\ macOS\ High\ Sierra\ Beta.app/Contents/SharedSupport/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase
cp /tmp/BaseSystem.dmg /Volumes/OS\ X\ Base\ System

hdiutil detach /Volumes/OS\ X\ Base\ System/
hdiutil convert /tmp/HighSierra.cdr.dmg -format UDTO -o /tmp/HighSierra.iso
mv /tmp/HighSierra.iso.cdr ~/Desktop/HighSierra.iso
rm /tmp/HighSierra.cdr.dmg

 

[Crash0veride]

I don't know about all the making an iso using a script jazz, but could you create a regular bootable USB using "creatinstallmedia" and then use "dd" in terminal to turn the usb image into an ISO? More of a workaround than a solution, but might help.

 

[br0adband]

Hadn't gone THAT far with the process but for now it seems there's a glitch in the sense that the Packages contents is not where it is in Sierra and previous installer.app setups, it's been shifted so, during the script execution what it finds is just a symbolic link and it craps with an error but the creation continues. I copied all the Packages manually and then continued and it still didn't work so, I'll keep hoping for a solution soon enough. I'm still mainly a Windows person by default so this kind of stuff (using a late 2012 MBP) and all the scripting finer points is just experimental stuff I do to learn some new tricks I suppose.

It'll happen sooner or later.

 

[chrfr]

The topic at hand is taking the Install macOS High Sierra Beta.app file (and soon enough the final release in a few days as well) that is downloaded from the App Store and then convert that to a bootable ISO file (just like we've done in the past with El Capitan, Sierra, and previous releases as well) successfully and have that work for installing the OS in VMware/VirtualBox/Parallels.

VMWare Fusion 8.5.8 will install High Sierra from the installer app, without having to make an ISO or do anything special to make it happen, just as it does with earlier versions of the OS.

 

[br0adband]

Yes, I realize that, and older versions of VirtualBox could actually install from a .dmg and I never could figure out why they removed that capability but they did so, still the quest to make the proper working bootable ISO continues.

 

[tywebb13]

I repost instructions here removing the word Beta because High Sierra is released now (and I also added another line rm /tmp/BaseSystem.dmg because I didn’t want that staying in there):

hdiutil attach /Applications/Install\ macOS\ High\ Sierra.app/Contents/SharedSupport/InstallESD.dmg -noverify -mountpoint /Volumes/highsierra

hdiutil create -o /tmp/HighSierraBase.cdr -size 7316m -layout SPUD -fs HFS+J

hdiutil attach /tmp/HighSierraBase.cdr.dmg -noverify -mountpoint /Volumes/install_build

asr restore -source /Applications/Install\ macOS\ High\ Sierra.app/Contents/SharedSupport/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase

cp -R /Volumes/highsierra/Packages /Volumes/OS\ X\ Base\ System/System/Installation

hdiutil detach /Volumes/OS\ X\ Base\ System/

hdiutil detach /Volumes/highsierra/

mv /tmp/HighSierraBase.cdr.dmg /tmp/BaseSystem.dmg

hdiutil create -o /tmp/HighSierra.cdr -size 8965m -layout SPUD -fs HFS+J

hdiutil attach /tmp/HighSierra.cdr.dmg -noverify -mountpoint /Volumes/install_build

asr restore -source /Applications/Install\ macOS\ High\ Sierra.app/Contents/SharedSupport/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase

cp /tmp/BaseSystem.dmg /Volumes/OS\ X\ Base\ System

hdiutil detach /Volumes/OS\ X\ Base\ System/

hdiutil convert /tmp/HighSierra.cdr.dmg -format UDTO -o /tmp/HighSierra.iso

mv /tmp/HighSierra.iso.cdr ~/Desktop/HighSierra.iso

rm /tmp/HighSierra.cdr.dmg

rm /tmp/BaseSystem.dmg

Then I burnt it to a bluray (couldn’t fit it on DL DVD because it is over 9gb!)

The bluray starts to boot, but then just hangs. I think it’s a coaster now. Time to give up on that one. There might be a way to get it to work. The BaseSystem.chunklist doesn’t seem to have been copied over either. Shouldn’t that be there too?

 

[SignedAdam]

This is really annoying that the rest of us with mac's that have (The) superdrives "for thoses who dont know, they are what apply uses to call its dvd/cd reader and writers" are no longer useful for installing the very thing that makes the mac work! i'm taking about the operating system! I hope someone does work out away to put the installer on to a 8gb dvd, must be away to make it smaller and even have it work!

 

[rot3r]

I don't know what is wrong with APPLE!
why change everything every time!
i can make bootable on a DVD-DL with the instruction of tywebb13 for the sierra with a little modification,it boot but after booting show high sierra installation but give me the error of "/system/installation/packages/OSInstall.mpkg appear to be missing or damage " but this file exist on this path!

 

[tbohlsennswssrg]

Have you tried creating a read/write disk image, mounting that and using the createinstallmedia command to install the files to that disk image and converting that image to a ISO using the hdiutil makehybrid -o image source command?

 

[LarryJoe33]

I use CCC5 to create a disk image to a network drive. I have no issues doing this with all betas and the GM. It’s been failing with the final release.

 

[br0adband]

ty's instructions won't work, unfortunately, because of the fact that the files aren't being copied over properly. The script that I provided has the same issue but at least it doesn't go into the actual installer, it starts up the Remote Recovery or install thing, whatever it's called anymore.

I ended up just giving up in the process and following just the first portion of the script I posted which creates the BaseSystem.dmg, then I converted that to an ISO and did the install that way (it does the remote install directly off Apple's servers).

It really sucks to have to use that process and not be able to use the installer files that are so obviously right there on the ISO when I make a full ISO but, something has obviously changed and I'm simply not experienced enough with the way the installer app is handled. I'm sure someplace in the install script there's the necessary info but it's beyond my abilities at this time, unfortunately.

The script that I posted, found someplace else on Github by a person that swore up and down both sides of reality that it worked fine for him with High Sierra betas, but since the final release a few days ago that person hasn't been heard from so I'm hoping he/she/it might be able to take a look and figure out what's changed.

Upon execution of that script when it gets to line #5 it will error because it can't write new data to the place where the Packages alias exists (created during the command from line #4). In the past that command copies the Packages subdirectory over, entirely, which is "the meat and the potatoes" of the InstallESD.dmg content to begin with, that is High Sierra itself basically.

The second part of that script does the same thing again but then goes further to copy the "custom" BaseSystem.dmg (which is like 7.8GB in size at that point) into the root directory of the final install layout which of course seems totally wrong: no previous version of macOS or OSX had a dmg in the root directory, all the necessary files ended up being in the SharedSupport directory or someplace not the root level directory.

I would love to figure out just what the hell Apple has actually changed in the layout once and for all but I'm not gonna get my hopes up at this point. I made that much smaller ISO with just the BaseSystem.dmg created from the InstallESD.dmg and that was good enough.

So in about 10 days of experimentation I've downloaded High Sierra betas and the final release like 35 times which ends up being like 125GB of my bandwidth on my Internet connection (not that I care) and probably added 2-2.5TB of writes to my SSD by creating VMs then shredding them over and over again, copying them, moving them, etc.

It hasn't been fun by any measure but it's something to do I suppose in the search for a solution that does actually work properly.

 

[tywebb13]

Have you tried creating a read/write disk image, mounting that and using the createinstallmedia command to install the files to that disk image and converting that image to a ISO using the hdiutil makehybrid -o image source command?

Tried that years ago with mavericks and it didn’t work then so expect that it won’t work now.

But I might be wrong so I gave it a go. I also burnt it to disk too.

Result: another coaster.

So I was right. It won’t work. At least it was a bit smaller this time and so the new coaster is a DL DVD coaster instead of a bluray coaster.

 

[br0adband]

NOTE: originally this method did work for me one single time aka the first time I made an ISO with this method - but then I decided to do it a second time (after deleting the first VM I created) and in the second attempt the virtual hard drive is not bootable, not even using the bless command to point to it as the Startup volume so now I'll do some troubleshooting.

Again, this method may or may not work for you and apparently tywebb13 commented in the very next post that it still doesn't appear to create a proper bootable DVD if and when the ISO is burned to physical media so, the quest still continues...

==========

This is not my solution, I did not come up with it nor did I post it originally, I found it at the same place I located the script I shared in the OP above (post #1 of this thread, aka Original Post in case you missed that) and had asked if anyone could help provide a working one since that one posted above didn't seem to cut it. The person that eventually provided the working script did so here:

https://gist.github.com/agentsim/00cc38c693e7d0e1b36a2080870d955b

and goes by the name halabibk so thank that person if you see him/her around someplace online. Anyway, the final confirmed working ISO (as I just used it to create the ISO, about 5.2GB in size) works like this and of course the presumption is that you have the Install macOS High Sierra.app sitting in your Applications folder:

hdiutil create -o /tmp/HighSierra.cdr -size 5130m -layout SPUD -fs HFS+J
hdiutil attach /tmp/HighSierra.cdr.dmg -noverify -mountpoint /Volumes/install_build
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build
mv /tmp/HighSierra.cdr.dmg ~/Desktop/InstallSystem.dmg
hdiutil detach /Volumes/Install\ macOS\ High\ Sierra
hdiutil convert ~/Desktop/InstallSystem.dmg -format UDTO -o ~/Desktop/HighSierra.iso

then manually rename the HighSierra.iso.cdr to HighSierra.iso (or whatever name you want) and voila, you're done - and of course you can then delete the InstallSystem.dmg as well.

As noted, I did this before making this post and tested it with the NIC disabled and now when it gets to the dialogue it doesn't show "Reinstall macOS High Sierra" anymore but instead what I was always hoping to see which is "Install macOS High Sierra" and it installs relatively quick as expected from the ISO media.

So, that's that, and an even easier solution than some of us have been using in the past.

EDITED to add the NOTE at the beginning of the post later that same evening.

EDITED again to add the info about detaching the .dmg to be able to convert it and the command to do the detach - you can also just choose to "Eject" the attached image in Finder as well.

 

[tywebb13]

As noted in the edited title, SUCCESS!!!

Note: this is not my solution, I did not come up with it nor did I post it originally, I found it at the same place I located the script I shared in the OP above (post #1 of this thread, aka Original Post in case you missed that) and had asked if anyone could help provide a working one since that one posted above didn't seem to cut it. The person that eventually provided the working script did so here:

https://gist.github.com/agentsim/00cc38c693e7d0e1b36a2080870d955b

and goes by the name halabibk so thank that person if you see him/her around someplace online. Anyway, the final confirmed working ISO (as I just used it to create the ISO, about 5.2GB in size) works like this and of course the presumption is that you have the Install macOS High Sierra.app sitting in your Applications folder:

hdiutil create -o /tmp/HighSierra.cdr -size 5130m -layout SPUD -fs HFS+J
hdiutil attach /tmp/HighSierra.cdr.dmg -noverify -mountpoint /Volumes/install_build
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build
mv /tmp/HighSierra.cdr.dmg ~/Desktop/InstallSystem.dmg
hdiutil convert ~/Desktop/InstallSystem.dmg -format UDTO -o ~/Desktop/HighSierra.iso

then manually rename the HighSierra.iso.cdr to HighSierra.iso (or whatever name you want) and voila, you're done - and of course you can then delete the InstallSystem.dmg as well.

As noted, I did this before making this post and tested it with the NIC disabled and now when it gets to the dialogue it doesn't show "Reinstall macOS High Sierra" anymore but instead what I was always hoping to see which is "Install macOS High Sierra" and it installs relatively quick as expected from the ISO media.

So, that's that, and an even easier solution than some of us have been using in the past.

Glad you got a working method for bootable iso. Unfortunately though it still doesn’t work for dvd. I burnt the iso to dvd, it starts to boot up, just like the rest of my coasters before, and then just hangs and doesn’t fully boot. So yet another coaster unfortunately.

 

[br0adband]

Yeah, I had the most interesting experience just now. Was experimenting as usual and decided to make yet another clean High Sierra install and this time, for some reason I can't explain yet, the installation does not work properly meaning after I get the installation itself done from the ISO it boots back to the ISO a second time. So I started Terminal from the installer, used the bless command to point the boot parameters to the virtual hard drive, and it's still not working.

The first time I did this earlier it worked without a single hitch, now - of course after I deleted that first virtual machine I made for testing that new method - I can't get it to function a second time so, I'm going to edit the post above and say it's not quite the success I thought it was and now I'll work on troubleshooting to see what's going on with this crap once again.

Part deux:

Ah, that would do it: it's converting to APFS hence not being bootable for me. Even though I'm manually telling it to format the volume as HFS+ it's then putting that inside the APFS container and I think that's where all the issues are coming from (yes I'm installing on an SSD). Will try this a second time with the virtual hard drive sitting on a physical hard drive and see what happens.

 

[tywebb13]

Yeah, I had the most interesting experience just now. Was experimenting as usual and decided to make yet another clean High Sierra install and this time, for some reason I can't explain yet, the installation does not work properly meaning after I get the installation itself done from the ISO it boots back to the ISO a second time. So I started Terminal from the installer, used the bless command to point the boot parameters to the virtual hard drive, and it's still not working.

The first time I did this earlier it worked without a single hitch, now - of course after I deleted that first virtual machine I made for testing that new method - I can't get it to function a second time so, I'm going to edit the post above and say it's not quite the success I thought it was and now I'll work on troubleshooting to see what's going on with this crap once again.

Part deux:

Ah, that would do it: it's converting to APFS hence not being bootable for me. Even though I'm manually telling it to format the volume as HFS+ it's then putting that inside the APFS container and I think that's where all the issues are coming from (yes I'm installing on an SSD). Will try this a second time with the virtual hard drive sitting on a physical hard drive and see what happens.

I have a theory for why it isn't working for bootable dvds or blurays.

On apple's page https://support.apple.com/en-au/ht201372 on how to create bootable usbs it used to say the usb should have at least 8GB of free space. And that was even for El Capitan which was much bigger than High Sierra.

Now with High Sierra they have changed that to say "Make sure that it has at least 12GB of available storage space".

So why would High Sierra need so much more free space than even El Capitan which was even bigger than High Sierra?

I reckon new stuff is being written onto the usb as it boots taking up more space. A potentially bootable dvd or even bluray can't write that new stuff to the disk as it boots and hence stalls.

So this behaviour is quite different for High Sierra than for previous versions.

It will be OK for USBs which are big enough but won't work for dvds or blurays - even though a bluray has heaps of extra space.

On the other hand I too have had partial success with this.

The DVD wouldn't boot up on a computer which already was apfs formatted.

But the very same DVD did actually boot up another computer which was formatted as hfs+.

So it is a coaster for some computers, and a bootable dvd for others!

That doesn't necessarily invalidate my theory though. It might be trying to write the extra stuff to itself when trying to boot up on an apfs computer, but not need to do this if the computer is hfs+.

In the first command the bit with "-layout SPUD -fs HFS+J" means that the iso (hence the dvd) is hfs+ formatted - and therefore can only boot up hfs+ computers.

Maybe we actually need 2 isos and 2 dvds, one formatted as hfs+ and the other as apfs - alternatively a dual bootable bluray with 2 partitions each with the High Sierra installer - but one formatted as hfs+ and the other as apfs.

 

[br0adband]

Ok, so I redid this situation and instead of creating the VM on my primary SSD I chose a secondary physical hard drive used for raw storage of content (slow 5400 rpm so not a real performer) and yep, everything installed just fine the 3rd time around without any issues whatsoever. It did keep my choice of HFS+ for the partition for the virtual hard drive and it's good to go.

I can't say why this is the case, I was reading that some instances with APFS wouldn't be bootable by design, maybe it's borked with virtual hard drives in that respect and perhaps there's a flag someplace that can be flipped or involved to push it through, I really don't know at this point but again on the 3rd attempt and with using a physical hard drive to store the VM (including the virtual hard drive's vmdk file) it had no issues whatsoever.

So of course me being me I decided a 4th attempt, back on the SSD once more, and again, no bootable partition found which gives me the reason to conclude there's something funky going on with the APFS boot capacity and a virtual hard drive.

I haven't tried VMware 14 which was just released, can't really see a need for me to fork over more money for a newer version but it remains to be seen if this APFS issue is just a problem with my hardware or overall but then again most folks don't use ISOs anymore for direct installation of the OS as USB sticks have taken over in that respect.

 

[tywebb13]

With further investigations I have continued to have mixed success/failure.

On the one hand I was able to use the dvd to successfully install High Sierra. That is the ultimate test of a bootable dvd, not just that it boots.

On the other hand I wasn't able to make a bootable iso in apfs format hence not the dual bootable bluray in both apfs and hfs+ formats.

So for now at least what we have is a method to get a bootable dvd - but it only boots on computers formatted as hfs+, not apfs.

That might be OK for now since many compatible macs can be formatted as either (certainly all as hfs+ at least) it does not bode well for the future.

Unless someone can come up with an apfs version of the bootable High Sierra iso then maybe soon we will see the bootable iso not be a possibility for the future, eg., new macs maybe next year only formattable as apfs.

 

[toru173]

I wonder if you can make an ISO using my method, outlined at https://forums.macrumors.com/thread...ted-macs-thread.2048478/page-20#post-24856892

I know if I attempt to boot the created DMG as an ISO in virtual box, it boots and installs without issue. Maybe it will work on real hardware?

 

[dav777]

My iso boots up in virtualbox but I can't install as no hard disks are detected. Anyone have any solution or ideas?

 

[br0adband]

My iso boots up in virtualbox but I can't install as no hard disks are detected. Anyone have any solution or ideas?

There's a glitch with High Sierra's Disk Utility in that it won't show all your drives by default so click View - Show All Devices and it should then show your drives including the virtual hard drive you're attempting to install the OS on.

As noted in my post above, if you're installing the OS and the location you've chosen for the virtual machine itself - including where it stores the vmdk virtual hard drive file(s) - is on an SSD it's going to convert/encapsulate HFS+ inside an APFS container and that could have issues with booting properly.

What I did was to create a virtual machine stored on a physical hard disk and then after it was set up fully (account created, latest updates installed - just iTunes so far - and some apps installed) was then to transfer that virtual machine aka the entire folder it's stored in to my primary SSD and then opened it from there without issues and of course the speed boost from running off the SSD.

It just can't create a new VM that resides on an SSD without APFS. I did try to use the --converttoapfs NO flag with the InstallAssistant but it doesn't work either so, it's possible to get it all done but it's just not as easy as it potentially could be.

Of course, if you want APFS or you're experimenting to learn more about that file system then by all means, install on an SSD directly and you should be good to go presuming that it boots, of course.

 

[dav777]

There's a glitch with High Sierra's Disk Utility in that it won't show all your drives by default so click View - Show All Devices and it should then show your drives including the virtual hard drive you're attempting to install the OS on.

As noted in my post above, if you're installing the OS and the location you've chosen for the virtual machine itself - including where it stores the vmdk virtual hard drive file(s) - is on an SSD it's going to convert/encapsulate HFS+ inside an APFS container and that could have issues with booting properly.

What I did was to create a virtual machine stored on a physical hard disk and then after it was set up fully (account created, latest updates installed - just iTunes so far - and some apps installed) was then to transfer that virtual machine aka the entire folder it's stored in to my primary SSD and then opened it from there without issues and of course the speed boost from running off the SSD.

It just can't create a new VM that resides on an SSD without APFS. I did try to use the --converttoapfs NO flag with the InstallAssistant but it doesn't work either so, it's possible to get it all done but it's just not as easy as it potentially could be.

Of course, if you want APFS or you're experimenting to learn more about that file system then by all means, install on an SSD directly and you should be good to go presuming that it boots, of course.

Thanks for the info. Busy installing to a normal disk. So far so good
Spoke too soon. System installed boots to UEFI prompt Will continue the fight tomorrow..

 

[br0adband]

Thanks for the info. Busy installing to a normal disk. So far so good
Spoke too soon. System installed boots to UEFI prompt Will continue the fight tomorrow..

Which is what happened to me as I noted above and I suspect it's got to do with the APFS container holding the HFS+ partition, or you might have chosen to just use APFS completely without the container aspect, I don't know. But in my testing so far if the virtual hard drive has anything APFS related going on the virtual machine will not boot and I can't say for sure why. Maybe there's an issue with it simply not being able to read the file system (unlikely but again, I don't know for sure) so it can gain access to the boot.efi file it needs so it just hangs.

I wonder if VMware 14 has addressed this issue, I might have to get the version 14 Player and do so some testing and see what happens with that.

 

[jonh229]

Anyway, the final confirmed working ISO (as I just used it to create the ISO, about 5.2GB in size) works like this and of course the presumption is that you have the Install macOS High Sierra.app sitting in your Applications folder:

Just a few questions please. I'm quite new to this, wanting to install H.S. on Linux host in vBox. On a macbook I've downloaded the macOS H.S.app, and to avoid confusion from bouncing apps & audible reminders moved it to ~/Downloads.
1) There are the instructions in post #1, and more instructions in post #13. The way I read it, I can use instructions only from post #13, correct?
2) And I must change the path to reflect current file location. Will that work or do I have to move it back to the original Applications folder before running the script?
3) vBox should accept a bootable .iso as install media, although I've never tried that, so that is my plan.
4) Just in case item 3 doesn't work, referring to 5.2GB dvd, my only experience is w/ 4.7GB dvd's? Did technology move ahead while I was asleep or is there newer media that works with current burners?
5) I don't know what apfs is, but I will look that up shortly. I think hfs+ will suit me just fine.

Hoping the above sounds like a workable plan. Comments?

 

[br0adband]

1) Yes you'd use the script in post #13 (what luck, eh?) - the 1st post was the older script I tracked down but it didn't create a working bootable ISO.

2) As for changing the path, my suggestion is to leave the path as it is and make a copy of the Install macOS High Sierra.app and paste that into the Applications folder which is where it should be anyway. This way you'd have the "backup" in Downloads but wouldn't need to alter the script as it is.

3) VirtualBox shouldn't have any issues at all with booting from the ISO this creates, nope.

4) DVD5 aka single layer blank media is the most common but DVD9 aka dual layer blank media is also available if necessary but those are obviously more expensive and in my experience of attempting to use DVD9 blank media is fraught with issues that don't exist with single layer media so I don't recommend actually using it unless absolutely necessary. Yes the ISO is 5.2GB in size, and would require DVD9 blank media to burn it to but in today's age of USB sticks and doing things with virtual machines, I can't imagine anyone would actively need to make this into physical DVD media. DVD5 means it's roughly 5GB of storage (ok, so 4.7GB or so) and DVD9 means roughly 9GB of storage (at about 8.3GB), it's just an easier way to refer to the media itself instead of saying single layer or dual layer.

5) APFS is Apple's new file system, designed from the ground up to offer better performance (in most disk based I/O operations) with Flash media of various kinds, mostly for SSDs obviously. It is compatible with physical hard drives even in spite of what Apple is telling people but because it's literally "new" in most senses of the word, it has very little documentation being provided, and typically when a new file system is created on any platform it takes years of testing before it's given the go-ahead but Apple isn't really providing the info that third parties want so they can understand this new file system nearly as well as HFS+ is. Doing that, limiting the scope of info provided, keeps those third party developers from being able to trust this new file system completely so a great many of them are having a "wait and see" approach.

Personally I think that Apple's choice to effectively force APFS on people is not right at this point in time but it's what they're doing and there's no turning back now. If you install High Sierra on an SSD natively it's going to use APFS and if you choose HFS+ with Disk Utility at the beginning of the installation it will (based on my experience so far) still use APFS and create a container partition with the HFS+ one inside it.

Anyway, that should help somewhat, at least that's the hope. The one thing to be on the lookout for as I mentioned in post #21 above is that when you start the installer and you use Disk Utility to partition/format the virtual hard drive you want to install High Sierra on it may not show up as an available drive. At that point you click the icon in the upper left corner of Disk Utility to alter the View settings to All Devices and that should cause the virtual hard drive - assuming it's attached to the VM as required - to then be visible so you can erase/format it.

Good luck...