The Guy Named Bob Mac OS

Whitney Elizabeth Houston was born on August 9, 1963, in what was then a middle-income neighborhood in Newark, New Jersey. She was the daughter of ex-Army serviceman and Newark city administrator John Russell Houston Jr. And gospel singer Emily 'Cissy' (Drinkard) Houston. Turn on Finder integration. If you’re on OSX 10.10 or higher, get sync status directly from Finder by enabling Finder overlays in Settings. First, click the Apple logo in the top left corner of your Mac Desktop and select System Preferences, then select Extensions in the top-level menu (shown in the 3rd row from the top). Toggle on the OneDrive Finder Integration to enable Finder overlays.

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This document is a Mac OS X manual page. Manual pages are a command-line technologyfor providing documentation. You can view these manual pages locally using theman(1) command.These manual pages come from many different sources, and thus, have a variety of writingstyles.

For more information about the manual page format, see the manual page for manpages(5).

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Set volume bootability and set the active boot volume.
bless has 5 modes of execution: Folder Mode, Mount Mode, Device Mode, NetBoot Mode, and Info Mode.

Bless predates SIP, APFS, and T2 Secure Boot. On modern Macs, bless should be used with great caution as it may render the Mac unbootable.

In macOS 10.11 and above, bless should not be used to try to set the startup disk as System Integrity Protection (SIP) is in place.
Instead use systemsetup -setstartupdisk

For a full description of all the bless options see man bless the options available for bless will vary according to the version of macOS you are running.

Examples

INFO MODE
Gather information about the currently selected volume (as determined by the firmware):

sudo bless --info

Gather plist information about the currently selected volume (as determined by the firmware), suitable for piping to a program capable of parsing Property Lists:

sudo bless --info --plist

FOLDER MODE
To bless a volume with only Mac OS 9:

bless --folder9 '/Volumes/Mac OS 9/System Folder' --bootBlockFile '/usr/share/misc/bootblockdata'

To bless a volume with only macOS or Darwin, and create the BootX and boot.efi files as needed:

bless --folder '/Volumes/Mac OS X/System/Library/CoreServices' --bootinfo --bootefi

MOUNT MODE
To set a volume containing either Mac OS 9 and macOS to be the active volume:

bless --mount '/Volumes/Mac OS' --setBoot

NETBOOT MODE
To set the system to NetBoot and broadcast for an available server:

bless --netboot --server bsdp://255.255.255.255

“If everything seems under control, then you're not going fast enough” - Mario Andretti

Related macOS commands: