An even more robust edition of my previous MountEFI scripts.
Other scripts can call this script to do a silent mount - and receive a 0 on success, or 1 (or higher) on failure.
For example: If another script calls MountEFI.command disk0 then my script would mount without user interaction, and return a 0 on success, or a 1 on failure. This can also take multiple EFIs to mount - MountEFI.command disk0 / disk3 would mount the EFIs connected to disk0, the boot drive (/), and disk3 if they exist.
Do the following one line at a time in Terminal:
git clone https://github.com/corpnewt/MountEFI
cd MountEFI
chmod +x MountEFI.command
Then run with either ./MountEFI.command or by double-clicking MountEFI.command