.\" from Symmetric Computer Systems.
.\" Modifications Copyright (c) 1987 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)disklabel.8	6.4 (Berkeley) %G%
.\"
.TH DISKLABEL 8 ""
.UC 5
.SH NAME
disklabel \- read and write disk pack label
.SH SYNOPSIS
.B disklabel
[
.B \-r
]
.I disk
.br
.B disklabel \-w
[
.B \-r
]
.I disk
.I disktype
[
.I packid
[
.I priboot secboot
] ]
.br
.B disklabel \-e
[
.B \-r
]
.I disk
.br
.B disklabel \-R
[
.B \-r
]
.I disk protofile
[
.I priboot secboot
]
.SH DESCRIPTION
.I Disklabel
can be used to install, examine or modify the label on a disk drive or pack.
When writing the label, it can be used
to change the drive identification,
the disk partitions on the drive,
or to replace a damaged label or bootstrap.
The disk label is located on one of the first sectors
of each disk (usually block 0).
On machines that require a block-0 bootstrap (VAX 11/750),
the label is inserted into the bootstrap program.
This information is used by the system disk driver and by the bootstrap
program to determine how to program the drive.
There are several forms of the command that display, install or modify
the label on a disk.
Each form has an additional option,
.BR \-r ,
which causes the label to be read from or written to the disk directly,
rather than going through the system's in-core copy of the label.
When writing, the in-core copy is also updated if possible.
This option may allow a label to be installed on a disk
without kernel support for a label, such as when labels are first installed
on a system.
.PP
The first form of the command is used to examine the label on the named
disk drive (e.g. hp0 or /dev/rhp0c).
It will display all of the parameters associated with the drive
and its partition layout.
The kernel's in-core label is displayed;
if the disk has no label, or the partition types on the disk are incorrect,
the kernel may have constructed or modified the label.
If the
.B \-r
flag is given, the label from the raw disk will be displayed rather
than the in-core label.
.PP
The second form of the command, with the
.B \-w
flag, is used to write a standard label on the designated drive.
The required arguments to
.I disklabel
are the drive to be labelled (e.g. hp0), and
the drive type as described in the
.IR disktab (5)
file.
The drive parameters and partitions are taken from that file.
If different disks of the same physical type are to have different
partitions, it will be necessary to have separate disktab entries
describing each or to edit the label as described below.
The first optional argument is a pack identification, up to 16 characters.
The pack id must be quoted if it contains blanks.
If the
.B \-r
flag is given, the disk sectors containing the label and bootstrap
will be written directly,
otherwise the existing label will be modified in place without modifying
the bootstrap.
If the disk does not already have a label, the
.B \-r
flag must be used.
In either case, the kernel's in-core label is replaced.
.PP
Alternate versions of the bootstrap files may be specified
after the pack identifier.
If an alternate bootstrap is not specified, the standard bootstrap will be used.
The bootstrap programs are located in
.IR /usr/mdec .
The names of the bootstrap programs may be specified in
.IR disktab (5);
if not specified
with default names of the form
.IR disktype boot
for the primary (block 0) bootstrap, and
.RI boot disktype
for the secondary (block 1-15) bootstrap;
for example, /usr/mdec/hpboot and /usr/mdec/boothp.
.PP
An existing disk label may be edited by using the
.B \-e
flag.
The label is read from the in-core kernel copy,
or directly from the disk if the
.B \-r
flag is also given.
The label is formatted and then supplied to an editor for changes.
If no editor is specified in an EDITOR environment variable,
.IR vi (1)
is used.
When the editor terminates, the formatted label is reread
and used to rewrite the disk label.
.PP
Finally,
with the 
.B \-R
flag,
.I disklabel
is capable of restoring a disk label that was formatted
in a prior operation and saved in an ascii file.
The prototype file used to create the label is in exactly the same format
that is produced when reading or editing a label.
If the
.B \-r
option is also given,
a block-0 bootstrap is installed on machines that use one;
either the disktype or the names of the bootstrap files must be specified
on such machines.
.SH FILES
/etc/disktab
.br
/usr/mdec/\fIxx\fPboot
.br
/usr/mdec/boot\fIxx\fP
.SH "SEE ALSO"
disktab(5), disklabel(5)