NetBSD/usr.sbin/sunlabel/sunlabel.doc

sunlabel.c is the source.  It should build Just Fine on any NetBSD
machine; with -DDISTRIB, probably on many non-NetBSD machines - though
it may require a little tweaking on some.  It should work on both
big-endian and little-endian machines; though I have not personally
tried it on anything but SPARC and sun3, I have heard one report that
it worked on NetBSD/i386, which is little-endian.

Usage: pass a single argument, which is the disk device or file you
wish to read/write the label to/from.  sunlabel reads/writes only the
first 512 bytes of its argument.  There are also some flags supported:

	-d
		takes an argument specifying the disk device (in case
		you want to give something beginning with a -)
	-m
		says to ignore an incorrect magic number in the disk
		label
	-s
		says to ignore checksum errors when reading the label
	-n
		says to synthesize a new label rather than reading
		what's there
	-q
		quiet mode - don't print unnecessary babble (currently
		this suppresses the "sunlabel>" prompt).

Note that -fixmagic is dangerous, especially when combined with
-fixsum, since it will then happily believe whatever garbage it may
find in the label.  If you use these, you should check all values
carefully, both the values printed by L and the partition table printed
by P.

sunlabel prints a prompt "sunlabel>" and expects commands.  You can
type ? for help; as of this writing, the help is

	? - print this help
	L - print label, except for partition table
	P - print partition table
	[abcdefghijklmnop] <cylno> <size> - change partition
	V <name> <value> - change a non-partition label value
	W - write (possibly modified) label out
	S - set label in the kernel (orthogonal to W)
	Q - quit program (error if no write since last change)
	Q! - quit program (unconditionally) [EOF also quits]

(If built without special precautions, the S line is present only when
built on NetBSD.)

The a through p commands will accept, for the <size> parameter, the
nnn/nnn/nnn syntax used by SunOS 4.x format(8).  (For those not
familiar with this syntax, a/b/c means a cylinders + b tracks + c
sectors.  For example, if the disk has 16 tracks of 32 sectors, 3/4/5
means (3*16*32)+(4*32)+5=1669.  This calculation always uses the nsect
and ntrack values as printed by the L command; in particular, if they
are zero (which they will initially be if -new is used), this syntax is
not very useful.  Some additional strings are accepted.  For the
<cylno> parameter, "end-X" (where X is a partition letter) indicates
that the partition should start with the first free cylinder after
partition X; "start-X" indicates that the partition should start at the
same place as partition X.  For the <size> parameter, "end-X" indicates
that the partition should end at the same place as partition X (even if
partition X ends partway through a cylinder); "start-X" indicates that
the partition should end with the last cylinder before partition X; and
"size-X" means that the partition's size should exactly match partition
X's size.

Note that sunlabel supports 16 partitions.  SunOS supports only 8.
Labels written by sunlabel, when partitions i through p are all set
offset=0 size=0, are identical to Sun labels.  If any of the "extended"
partitions are nontrivial, information about them is tucked into some
otherwise unused (as far as I can tell) space in the Sun label format.
I don't know whether SunOS cares what's in that space; as far as I know
only NetBSD actually uses the extended information, and even that only
with my patches to do so.

The V command changes fields printed by the L command.  For example, if
the L command prints

	ascii: ST15230N cyl 5657 alt 2 hd 19 sec 78
	rpm: 0          pcyl: 0         apc: 0          obs1: 0
	obs2: 0         intrlv: 1       ncyl: 5657      acyl: 0
	nhead: 19       nsect: 78       obs3: 0         obs4: 0

then you could type "V ncyl 6204" to set the ncyl value to 6204, or
"V ascii Seagate ST15230N cyl 5657 hd 19 sec varying" to set the
ascii-label string to that string.  sunlabel performs very few
consistency checks on the values you supply, and the ones it does
perform never generate errors, only warnings; it's a YAFIYGI program.

I will be glad to correspond with anyone about this program.  I'm...

					der Mouse

			       mouse@rodents.montreal.qc.ca
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