The device syntax used in GRUB is a wee bit different from what you may
have seen before in your operating system(s), and you need to know it so
that you can specify a drive/partition.
Look at the following examples and explanations:
First of all, GRUB requires that the device name be enclosed with
`(' and `)'. The `fd' part means that it is a floppy
disk. The number `0' is the drive number, which is counted from
zero. This expression means that GRUB will use the whole floppy
Here, `hd' means it is a hard disk drive. The first integer
`0' indicates the drive number, that is, the first hard disk, while
the second integer, `1', indicates the partition number (or the
pc slice number in the BSD terminology). Once again, please note
that the partition numbers are counted from zero, not from
one. This expression means the second partition of the first hard disk
drive. In this case, GRUB uses one partition of the disk, instead of the
This specifies the first extended partition of the first hard disk
drive. Note that the partition numbers for extended partitions are
counted from `4', regardless of the actual number of primary
partitions on your hard disk.
This means the BSD `a' partition of the second hard disk. If you
need to specify which pc slice number should be used, use something
like this: `(hd1,0,a)'. If the pc slice number is omitted,
GRUB searches for the first pc slice which has a BSD `a'
Of course, to actually access the disks or partitions with GRUB, you
need to use the device specification in a command, like `root
(fd0)' or `unhide (hd0,2)'. To help you find out which number
specifies a partition you want, the GRUB command-line
(see Command-line interface) options have argument
completion. This means that, for example, you only need to type
followed by a <TAB>, and GRUB will display the list of drives,
partitions, or file names. So it should be quite easy to determine the
name of your target partition, even with minimal knowledge of the
Note that GRUB does not distinguish IDE from SCSI - it simply
counts the drive numbers from zero, regardless of their type. Normally,
any IDE drive number is less than any SCSI drive number, although that
is not true if you change the boot sequence by swapping IDE and SCSI
drives in your BIOS.
Now the question is, how to specify a file? Again, consider an
This specifies the file named `vmlinuz', found on the first
partition of the first hard disk drive. Note that the argument
completion works with file names, too.
That was easy, admit it. Now read the next chapter, to find out how to
actually install GRUB on your drive.
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