fsdb_hfs man page on HP-UX

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fsdb_hfs(1M)							  fsdb_hfs(1M)

       fsdb_hfs: fsdb - HFS file system debugger

       special blocknum]

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

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

   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.

       normally uses the first superblock for the file system, located at  the
       beginning  of the disk section, as the effective superblock.  An alter‐
       nate 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 different
       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  pre‐
       fixed  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.

       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
	      Directory slot offset
	      File print facility
	      Convert from i-number to inode address;
			for continuation inodes as well as primary inodes
	      General print facility
	      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 current
       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

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

       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 dec‐
       imal 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 frag‐
       ment 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 avail‐
       able 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.  (Fragments
       are numbered from zero).	 The desired print option letter  follows  the
       fragment	 number, if present, or the symbol.  This print facility 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
	      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

       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

       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.

       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.

       was developed by HP and AT&T.

       Static information about the file systems

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


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