Manual Pages  — BSDLABEL

bsdlabel – read and write BSD label

SYNOPSIS DESCRIPTION Disk Device Name General Options Reading the Disk Label Writing a Standard Label Editing an Existing Disk Label Restoring a Disk Label From a File Installing Bootstraps FILES SAVED FILE FORMAT EXAMPLES DIAGNOSTICS COMPATIBILITY SEE ALSO HISTORY

bsdlabel [-A] disk | -f file
bsdlabel -w [-amp;An] [-B [-b boot]] [-m machine] disk | -f file [type]
bsdlabel -e [-amp;An] [-B [-b boot]] [-m machine] disk | -f file
bsdlabel -R [-amp;An] [-B [-b boot]] [-m machine] [-f] disk | -f file protofile

The bsdlabel utility installs, examines or modifies the BSD label on a disk partition, or on a file containing a partition image. In addition, bsdlabel can install bootstrap code.

When specifying the device (i.e., when the -f option is not used), the /dev/ path prefix may be omitted; the bsdlabel utility will automatically prepend it.

The -A option enables processing of the historical parts of the BSD label. If the option is not given, suitable values are set for these fields.

The -f option tells bsdlabel that the program will operate on a file instead of a disk partition.

The -n option stops the bsdlabel program right before the disk would have been modified, and displays the result instead of writing it.

The -m machine argument forces bsdlabel to use a layout suitable for a different architecture. Current valid values are i386 and amd64. If this option is omitted, bsdlabel will use a layout suitable for the current machine.

To examine the label on a disk drive, use the form

bsdlabel [-A] [-m machine] disk

disk represents the disk in question, and may be in the form da0 or /dev/da0. It will display the partition layout.

To edit an existing disk label, use the form

bsdlabel -e [-amp;An] [-m machine] disk

This command opens the disk label in the default editor, and when the editor exits, the label is validated and if OK written to disk.

To restore a disk label from a file, use the form

bsdlabel -R [-amp;An] [-m machine] disk protofile

The bsdlabel utility is capable of restoring a disk label that was previously saved in a file in ASCII format. The prototype file used to create the label should be in the same format as that produced when reading or editing a label. Comments are delimited by ‘#’ and newline.

If the -B option is specified, bootstrap code will be read from the file /boot/boot and written to the disk. The -b boot option allows a different file to be used.

/boot/boot	Default boot image.
/etc/disktab
	Disk description file.

The bsdlabel utility uses an ASCII version of the label when examining, editing, or restoring a disk label. The format is:

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:    81920       16    4.2BSD     2048 16384  5128
  b:  1091994    81936      swap
  c:  1173930        0    unused        0     0         # "raw" part, don't edit

If the -A option is specified, the format is:

# /dev/da1c:
type: SCSI
disk: da0s1
label:
flags:
bytes/sector: 512
sectors/track: 51
tracks/cylinder: 19
sectors/cylinder: 969
cylinders: 1211
sectors/unit: 1173930
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:    81920       16    4.2BSD     1024  8192    16
  b:   160000    81936      swap
  c:  1173930        0    unused        0     0         # "raw" part, don't edit

Lines starting with a ‘#’ mark are comments.

The partition table can have up to 8 entries. It contains the following information:

#	The partition identifier is a single letter in the range ‘a’ to ‘h’. By convention, partition ‘c’ is reserved to describe the entire disk.
size	The size of the partition in sectors, K (kilobytes - 1024), M (megabytes - 1024*1024), G (gigabytes - 1024*1024*1024), % (percentage of free space after removing any fixed-size partitions other than partition ‘c’), or * (all remaining free space after fixed-size and percentage partitions). For partition ‘c’, a size of * indicates the entire disk. Lowercase versions of suffixes K, M, and G are allowed. Size and suffix should be specified without any spaces between them. Example: 2097152, 1G, 1024M and 1048576K are all the same size (assuming 512-byte sectors).
offset
	The offset of the start of the partition from the beginning of the drive in sectors, or * to have bsdlabel calculate the correct offset to use (the end of the previous partition plus one, ignoring partition ‘c’). For partition ‘c’, * will be interpreted as an offset of 0. The first partition should start at offset 16, because the first 16 sectors are reserved for metadata.
fstype
	Describes the purpose of the partition. The above example shows all currently used partition types. For UFS file systems and ccd(4) partitions, use type 4.2BSD. For Vinum drives, use type vinum. Other common types are swap and unused. By convention, partition ‘c’ represents the entire slice and should be of type unused, though bsdlabel does not enforce this convention. The bsdlabel utility also knows about a number of other partition types, none of which are in current use. (See the definitions starting with FS_UNUSED in <sys/disklabel.h> for more details.)
fsize	For 4.2BSD file systems only, the fragment size; see newfs(8).
bsize	For 4.2BSD file systems only, the block size; see newfs(8).
bps/cpg
	For 4.2BSD file systems, the number of cylinders in a cylinder group; see newfs(8).

The kernel device drivers will not allow the size of a disk partition to be decreased or the offset of a partition to be changed while it is open.

The disklabel utility appeared in BSD 4.3 Tahoe .