How to Create an External El Cap Startup Drive?

[profcah]

Hi All;

I need to create a USB drive with El Cap on it that I can start up other Macs with (I DO NOT want to create an installer drive; that I can do). I have a number of older macs that occasionally I need to start up from an external USB (preferred) stick so I can get unbacked up files off of before I do reinstalls of OS, etc. I have searched but not found instructions. Eventually, I would like to do this for other OS's so I can do test drives before installing them.

Please, any help is greatly appreciated!

Carl

 

[Lufbrarunner]

1. Format your external device.
2. open the El Capitan installer.
3. Continue through the install process and accept the licence agreement.
4. Click on 'Show all disks'
5. Choose your external drive.
6. Click install.

When the install is complete, you can use the boot with option key pressed, to choose your required boot device.

 

[profcah]

Thanks for your answer; this is what I have tried before and here is what happens when I do this:

-First, I formatted a 32 Gb flash drive using Mac journaled format and GUID partition
-Follow instructions above.
-After clicking install, it goes thru the license agreement, allows me to pick my external drive, starts installation;
-After first restart, it says 17 minutes remain for install, but after 1=2 minutes a dialog comes up saying "OSX could not be installed on your computer. No packages were eligible for install. Contact a service associate or try again."
-Try again, same thing.

I downloaded El Captain install from the Apple store and tried all of this again; same result.

Interestingly, two folders were placed on my flash drive: one called "OSX Install Data" and the other called "private".

Does anyone have any ideas or solutions? By the way, I have been able to create Install OSX USB drives, but cannot seem to only\make a flash drive that I can use to start my computers up from. Any help is welcome!!!

 

[Lufbrarunner]

There is a problem with the expiry date on the certificate for the installer.
Running date 0101010116 in the Terminal of the installer solves the problem. (After boot to the installer, you can locate Terminal in top bar > Utilities)