bless

Set volume boot capability and startup disk options. More information: https://ss64.com/osx/bless.html.

• Bless a volume with only Mac OS X or Darwin, and create the BootX and boot.efi files as needed:
  bless --folder {{/Volumes/Mac OS X/System/Library/CoreServices}} --bootinfo --bootefi
• Set a volume containing either Mac OS 9 and Mac OS X to be the active volume:
  bless --mount {{/Volumes/Mac OS}} --setBoot
• Set the system to NetBoot and broadcast for an available server:
  bless --netboot --server {{bsdp://255.255.255.255}}
• Gather information about the currently selected volume (as determined by the firmware), suitable for piping to a program capable of parsing Property Lists:
  bless --info --plist