grub-probe

grub-probe [OPTION...] [PATH]

--device DEVICE
    Probe only this device. If not specified, probe all block devices.

--target=TARGET
    Print the specified TARGET information instead of the device.

--directory=DIR
    Search for files in DIR instead of the current directory.

--file=FILE
    Search for FILE to find the root device.

--no-warn
    Suppress warnings.

--verbose
    Be verbose.

--help
    Display help message and exit.

--version
    Display version information and exit.

The `grub-probe` command is a utility used to gather information about various devices and filesystems, specifically to aid GRUB (Grand Unified Bootloader) in identifying them. It's commonly used during GRUB configuration to determine device paths (e.g., `/dev/sda1`) and filesystem types. `grub-probe` employs various heuristics and checks to determine this information. The tool can identify the root filesystem, partition layout, and other boot-related aspects. By default, grub-probe prints the device corresponding to the given path and optionally prints more device info. The most frequent use is finding the root device on which the OS is installed.

Possible --target values include:
fs: Filesystem type.
device: Device associated with the path (default).
drive: The drive device.
abstraction: Abstraction level.
Other targets exist for specialized GRUB configurations.

grub-probe /boot/grub: Determine the device containing the /boot/grub directory.
grub-probe --target=fs /boot: Find the filesystem type of /boot.

grub-install(8), grub-mkconfig(8)