Efi shell
From wikinotes
the UEFI shell is a scriptable commandline interface you can use to boot operating systems.
Tutorials
https://techlibrary.hpe.com/docs/iss/proliant_uefi/UEFI_TM_030617/GUID-D7147C7F-2016-0901-0A6D-000000000E1B.html
Basics
devices # list devices FS0: # choose a device to interact with (FS0, FS1, ...) [command] -? # show help # several of shell builtins are available alias cat ls cd cp dh date ftp # boot or display boot options boot dump # show installed boot options boot -d # show boot options in order boot -n 1 # boot first option # load uefi driver load foo.efi