hpux man page for fsdb_hfs

fsdb_hfs(1M)															      fsdb_hfs(1M)

NAME
       fsdb_hfs: fsdb - HFS file system debugger

SYNOPSIS
       special blocknum]

   Remarks
       Always execute the command (see fsck(1M)) after running

DESCRIPTION
       The command can be used to patch up a damaged file system after a crash.

   Options and Arguments
       recognizes the following options and arguments.

	      special	     The file name of the special file containing the file system.

	      Initially disable the error-checking routines
			     that  are used to verify the inode and fragment addresses.  See the symbol.  If used, this option must follow special
			     on the command line.

	      Use	     blocknum as the superblock for the file system.  If used, this option must follow special on the command line.

	      Specify the HFS file system type.

	      Echo the completed command line, but perform no other action.
			     The command line is generated by incorporating the user-specified options and  other  information	derived  from  the
			     file.  This option allows the user to verify the command line.

   Operation
       normally  uses  the  first  superblock  for the file system, located at the beginning of the disk section, as the effective superblock.	An
       alternate superblock can always be found at block typically block 16.  The option can be used to specify the superblock location.

       deals with the file system in terms of block fragments, which are the unit of addressing in the file system and the minimum unit  of  space
       allocation.   To avoid possible confusion, fragment is used to mean that, and block is reserved for the larger true block.  has conversions
       to translate fragment numbers and i-numbers into their corresponding disk addresses.  Also included are mnemonic offsets to access  differ-
       ent parts of an inode.  These greatly simplify the process of correcting control block entries or descending the file system tree.

       contains  several  error-checking routines to verify inode and fragment addresses.  These can be disabled if necessary by invoking with the
       optional argument, or by using the symbol.

       Numbers are considered decimal by default.  Octal numbers must be prefixed with a zero.	Hexadecimal numbers must be prefixed  with  During
       any assignment operation, numbers are checked for a possible truncation error due to a size mismatch between source and destination.

       reads a fragment at a time.  A buffer management routine is used to retain commonly used fragments of data in order to reduce the number of
       read system calls.  All assignment operations result in an immediate write-through of the corresponding fragment.

   Symbols
       The following symbols are recognized by

	      Escape to shell
	      Absolute address
	      Address arithmetic
	      Address arithmetic
	      Restore an address
	      Save an address
	      Numerical assignment
	      Incremental assignment
	      Decremental assignment
	      Character string assignment
	      Convert from fragment number to disk address (historically "block")
	      Directory slot offset
	      File print facility
	      Convert from i-number to inode address;
			for continuation inodes as well as primary inodes
	      General print facility
	      Quit
	      Byte mode
	      Double-word mode
	      Error checking flip-flop
	      Word mode
	      Hexadecimal flip-flop

       Dots, tabs, and spaces can be used as function delimiters, but are not necessary.  A line with just a newline character increments the cur-
       rent  address by the size of the data type last printed.  That is, the address is set to the next byte, word, double word, directory entry,
       or inode, allowing the user to step through a region of a file system.

       Information is printed in a format appropriate to the data type.  If the toggle is off, bytes, words, and double words are printed  in  the
       form:

       If the toggle is on, bytes, words, and double words are printed in the form:

       If the (byte) or (double-word) mode is in effect, the colon shown above is preceded by or respectively.

       Directories are printed as a directory slot offset followed by the decimal i-number and the character representation of the entry name.

       Inodes are printed with labeled fields describing each element.

   Print Facilities
       The  print facilities generate a formatted output in various styles.  Octal numbers are prefixed with a zero.  Hexadecimal numbers are pre-
       fixed with The current address is normalized to an appropriate boundary before printing begins.	It advances with the printing and is  left
       at  the address of the last item printed.  The output can be terminated at any time by typing the interrupt character.  If a number follows
       the symbol, that many entries are printed.  A check is made to detect fragment boundary overflows since	logically  sequential  blocks  are
       generally  not  physically  sequential.	If a count of zero is used, all entries to the end of the current fragment are printed.  The print
       options available are:

	      Print as octal bytes
	      Print as characters
	      Print as directories
	      Print as decimal words
	      Print as inodes (primary or continuation)
	      Print as octal words
	      Print as hexadecimal words

       The symbol prints data fragments associated with the current inode.  If followed by a number, that fragment of the file is printed.  (Frag-
       ments  are numbered from zero).	The desired print option letter follows the fragment number, if present, or the symbol.  This print facil-
       ity works for small as well as large files except for special files such as FIFOs, and device special files.

   Inode and Directory Mnemonics
       The following mnemonics are used for inode examination and refer to the current working inode:

	      Data block numbers
			(num is in the range 0 - 14)
	      Time last accessed
	      Continuation inode number
	      Last time inode changed
	      Group ID number
	      Link count
	      Major device number
	      Mode
	      Minor device number
	      Time last modified
	      File size in byte unit
	      User ID number

       The following mnemonics are used for directory examination:

	      I-number of the associated directory entry
	      Name of the associated directory entry

EXAMPLES
       Print i-number 386 in an inode format.
		      This now becomes the current working inode.

       Change the link count for the working inode to 4.

       Increment the link count by 1.

       Print in ASCII fragment zero of the file associated with the working inode.

       Print the first fragment-size piece of directory entries
		      for the root inode of this file system.

       Change the current inode to that associated with the
		      fifth directory entry (numbered from zero) found from the above command.	The first fragment's worth of bytes  of  the  file
		      are then printed in ASCII.

       Print the first fragment of the superblock of this file system
		      in hexadecimal.

       Change the i-number for the seventh directory slot
		      in the root directory to 3.  This example also shows how several operations can be combined on one command line.

       Change the name field in the directory slot to the given string.
		      Quotes are optional if the first character of the name field is alphabetic.

       Print the third fragment of the current inode as directory entries.

WARNINGS
       Only experienced users should use The failure to fully understand the usage of and the file system's internal organization can lead to com-
       plete destruction of the file system and total loss of data.

AUTHOR
       was developed by HP and AT&T.

FILES
       Static information about the file systems

SEE ALSO
       dumpfs(1M), fsck(1M), fsdb(1M), stat(2), dir(4).

STANDARDS CONFORMANCE
																      fsdb_hfs(1M)