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11.1 How to specify devices

The device syntax is like this:


`[]' means the parameter is optional. device should be either `fd' or `hd' followed by a digit, like `fd0'. But you can also set device to a hexadecimal or a decimal number which is a BIOS drive number, so the following are equivalent:


part-num represents the partition number of device, starting from zero for primary partitions and from four for extended partitions, and bsd-subpart-letter represents the BSD disklabel subpartition, such as `a' or `e'.

A shortcut for specifying BSD subpartitions is (device,bsd-subpart-letter), in this case, GRUB searches for the first PC partition containing a BSD disklabel, then finds the subpartition bsd-subpart-letter. Here is an example:


The syntax `(hd0)' represents using the entire disk (or the MBR when installing GRUB), while the syntax `(hd0,0)' represents using the first partition of the disk (or the boot sector of the partition when installing GRUB).

If you enabled the network support, the special drive, `(nd)', is also available. Before using the network drive, you must initialize the network. See Network, for more information.

If you boot GRUB from a CD-ROM, `(cd)' is available. See Making a GRUB bootable CD-ROM, for details.