Any way to properly back up the Installer file?

[definitive]

I've downloaded El Capitan from the App Store, and backed up the InstallESD.dmg file to an external drive by simply copying it from the main .app file. I've done this with previous versions of OS X as well. Now when I try to make an installer out of it with DiskMaker X, it doesn't seem to work, and tells me I can't use that file to create a USB installer.

Did I back the files up wrong, or is there some way to use InstallESD file to manually create the USB install drive using the Terminal?

 

[Gav2k]

You don't need to use disk maker to be honest and I never have. All the tools needed are on your mac.

https://support.apple.com/en-gb/HT201372

 

[simon lefisch]

Why not just backup the main El Cap app? I did the same with Sierra. Downloaded it from the App Store and zipped it up to store on my server. That way I can use the commands from the link provided in the post above mine to create a bootable USB if needed.

 

[NoBoMac]

What Gav2k said.

Seems, to me, that the Diskmaker route seems to be more problematic than stock OS X method. Seems like issues with recovery media almost always have "Diskmaker X" in the steps taken.

For what it's worth, have always used createmediainstall command with no issues: just last week, re-verified my El Cap install thumbdrives, no issue.

 

[Fishrrman]

The easiest thing to do is to just copy the entire El Cap installer from your Applications folder to wherever you wish to save it.

Then it will be preserved "as Apple sent it".

I keep archives of ALL important Apple software that I've installed, going back many years.

No need to fight with Apple's website to get the stuff again!