pfdisk.doc

又一个选择启动分区的程序源码

PFDISK(8)	      MAINTENANCE COMMANDS		PFDISK(8)





NAME
	pfdisk - partition fixed disk

SYNOPSIS
	pfdisk device

DESCRIPTION
	pfdisk partitions the fixed disk identified as device  into  (at
	most) four parts, each of which	may be independently loaded with
	an operating system.  The actual name of device	depends	 on  the
	operating  system  in  use.   For ESIX (System V/386) the device
	name is	either "/dev/rdsk/0s0" or "/dev/rdsk/1s0".   For  Minix,
	it is "/dev/hd0" or "/dev/hd5".	 For MS-DOS it is a single digit
	(zero or one).

	pfdisk reads the hard disk partition table from	 block	zero  of
	device	into  memory  and allows the user to examine, modify, or
	save the partition table.  A regular file may be used instead of
	a  real	 device	for testing purposes, though the device	geometry
	must be	specified manually, and	some  systems  will  requrire  a
	file-name argument with	the "R"	and "W"	commands (DOS, ESIX).

	The partition table on device is NOT modified unless  the  write
	command	(W) is used with no argument.

USAGE
  Commands
	All pfdisk commands  consist  of  a  command  word  followed  by
	optional  blank-separated command arguments.  Note that	only the
	first letter of	a command word is significant (except  for  "wq"
	and  "q!").  All command letters are accepted in either	upper or
	lower case.  Numeric arguments are  specified  using  C	 syntax.
	Extra arguments	are silently ignored.

	The commands are:

	?	Prints a command summary (help).

	1 sys_id first last sys_name
		Set the	partition  table  entry	 for  part  one,  using:
		sys_id	as  its	system ID code,	first as the lowest num-
		bered cylinder it uses,	last  as  the  highest	numbered
		cylinder  it uses, and sys_name	(optional) as the system
		name (in the menu name table).

	2|3|4 sys-id first last	sys-name
		Similar	to 1 but sets partition	 two,  three,  or  four,
		respectively.





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PFDISK(8)	      MAINTENANCE COMMANDS		PFDISK(8)





	A number
		Mark partition number as active	(so it will be used  for
		booting).   If	number	is  zero,  no  partition will be
		active.

	G cylinders heads sectors
		Inform pfdisk what the geometry	of the device is.

	I	Print a	summary	of the known ID	codes.

	L	List the partition table.  See Output Format below.

	Q	Quit without saving.  If the memory copy of  the  parti-
		tion  table  was  modified, a warning will be issued and
		the command ignored.

	Q!	Quit, even if the memory copy of the partition table was
		not saved.

	R file-name
		Read boot sector from  file-name  (if  given)  otherwise
		read from device.

	W file-name
		Write boot sector to  file-name.  (if  given)  otherwise
		write to device.

	WQ	Same as	"write"	followed by "quit".

	#	This line is a comment (to be ignored).

  Output Format
	Here is	a sample of the	output from the	L command:

	# Partition table on device: /dev/rdsk/0s0
	geometry 1222 15 34 (cyls heads	sectors)
	#  ID  First(cyl)  Last(cyl)  Name     # start,	length (sectors)
	1   4	   0	    127	      MS-LOSS  # 34, 65246
	2 129	 128	    255	      Minix    # 65280,	65280
	3   0	   0	      0		       # 0, 0
	4  99	 256	   1220	      ESIX     # 130560, 492150
	# note:	 last(4): phys=(1023,14,34) logical=(1220,14,34)
	active:	4

	This output format is carefully	constructed so that  it	 may  be
	saved in a file	 (by redirecting standard output) and later used
	as input (by redirecting standard input).  On a	UNIX system, one
	can save this output using the command:





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		(echo L) | pfdisk device-name >	save-file

	save-file is a complete	record of the  partition  table.   On  a
	UNIX system, one could use save-file to	re-initialize the parti-
	tion table using the command:

		(cat save-file ; echo wq) | pfdisk device-name

	Consistency of each partition table entry is checked  while  the
	table is listed.  Any inconsistencies discovered are reported in
	a commentary note as shown above.

  Physical vs. Logical
	Each partition table entry has both "physical" and  a  "logical"
	fields.	  The  physical	 fields	 specify  the lowest and highest
	cylinder,head,sector combinations to be	used in	that  partition.
	The  logical  start  field has the total number	of sectors which
	precede	this partition,	and the	logical	 length	 field	has  the
	total  number  of  sectors  contained  in this partition.  These
	fields should be self consistent unless	the disk has  more  than
	1024 cylinders.

	The physical cylinder fields are only ten-bits wide so the  con-
	tents are limited to 1023. The logical sector fields are 32 bits
	wide and always	show the true logical beginning	 and  length  of
	the partition.	Generally, the physical	start field is used only
	to locate the secondary	boot sector, and the logical  start  and
	length fields are used to actually delimit the partition used by
	a particular system.

  Partition Names
	The Name field in the partition	table is  treated  specially  if
	the  bootmenu  program	is installed in	the primary boot sector.
	(See the file bootmenu.doc for	more  information.)  pfdisk  can
	recognize  the	name  table  used  by bootmenu and will	show the
	actual names present in	that name table.  If any other boot pro-
	gram  is  used	then  the  Name	 field	reflects the result of a
	table-lookup of	the system ID.

	If you provide a name when  setting  any  partition  entry,  the
	boot-sector  is	 marked	as using a name	table, so that on subse-
	quent uses of pfdisk you will see the partition	names  you  have
	specified.

  Boot program replacement
	You can	replace	the boot program in  your  boot	 sector	 without
	affecting  the	partition  table  by  using  pfdisk  as	follows.
	First, (as always) save	a copy of the current boot sector (on  a





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PFDISK(8)	      MAINTENANCE COMMANDS		PFDISK(8)





	floppy)	using the "W file" command.  Then, use the "R file" com-
	mand to	read the new boot program.  If the boot	program	read  in
	is  less  than	446  bytes  long,  the	partition  table will be
	unchanged.

	Unlike the DOS or UNIX fdisk programs, pfdisk has NO  boot  pro-
	gram  compiled	into  its  executable image.  If you wish to use
	pfdisk to partition a newly formatted hard disk, you must have a
	boot  program image available to read in using the "r file" com-
	mand.  Two boot	programs, "bootmenu.bin" and "bootauto.bin"  are
	distributed  with  pfdisk  and	should	be found with its source
	files.	See the	file bootmenu.doc for further information  about
	these boot programs.

AUTHOR
	Gordon W. Ross





































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