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fsdb(8)								       fsdb(8)

       fsdb - File system debugger

       /usr/sbin/fsdb [options] path

       Display	usage  Override some error conditions Forces the path argument
       to be processed only as a regular file.	Set prompt to string Open  for

       The fsdb utility operates on a device file or a file system  image. The
       utility first attempts to use the path argument as a device  file.   If
       that  fails,  it	 attempts  to  use  the path argument as a file system
       image. To avoid conflict, you can specify the -f option	to  force  the
       path argument to be used as a file system image.

       You must be root to use this command.

       The  fsdb  command  can be used to repair a damaged file system after a
       crash. It has conversions to translate block 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.

       The  fsdb  command  contains  several error-checking routines to verify
       inode and block addresses. These can be disabled if necessary by invok‐
       ing fsdb with the -o option.

       The  fsdb command reads a block at a time and works with raw as well as
       block I/O. A buffer management routine is used to retain commonly  used
       blocks  of data in order to reduce the number of read system calls. All
       assignment operations result in an immediate write-through of the  cor‐
       responding block. Note that in order to modify any portion of the disk,
       fsdb must be invoked with the -w option.

       Wherever possible, adb-like syntax was adopted to promote  the  use  of
       fsdb through familiarity.

       Numbers	are  considered hexadecimal by default. However, you have con‐
       trol over how data is to be displayed or	 accepted.  The	 base  command
       displays	 or  sets  the	input/output  base.  Once  set, all input will
       default to this base and all output will be shown  in  this  base.  The
       base  can  be overridden temporarily for input by preceding hexadecimal
       numbers with '0x', preceding decimal numbers with '0t', or  octal  num‐
       bers  with  '0'.	 Hexadecimal numbers beginning with a-f or A-F must be
       preceded with '0x' to distinguish them from commands.

       Disk addressing by fsdb is at the byte level. However, fsdb offers many
       commands to convert a desired inode, directory entry, block, superblock
       etc. to a byte address. Once the address has been calculated, fsdb will
       record the result in dot.

       Several	global	values	are  maintained	 by  fsdb:  The	 current  base
       (referred to as base); the current address (referred to	as  dot);  the
       current inode (referred to as inode); the current count (referred to as
       count); and the current type (referred to as type). Most	 commands  use
       the preset value of dot in their execution. For example: > 2:inode

       will  first  set	 the  value of dot to 2, ':' will alert the start of a
       command, and the inode command will set inode to 2. A count  is	speci‐
       fied after a ','. Once set, count will remain at this value until a new
       command is encountered which will then reset the value back to  1  (the
       default). So, if >2000,400/X

       is  typed,  400 hex longs are listed from 2000, and when completed, the
       value of dot will be 2000 + 400 *  sizeof  (long).  If  you  press  the
       Return  key,  the output routine uses the current values of dot, count,
       and type and displays 400 more hex longs. An asterisk  (*)  causes  the
       entire block to be displayed.

       End  of fragment, block and file are maintained by fsdb.	 When display‐
       ing data as fragments or blocks, an error message is displayed when the
       end of fragment or block is reached. When displaying data using the db,
       ib, directory, or file commands, an error message is displayed  if  the
       end  of file is reached. This is mainly needed to avoid passing the end
       of a directory or file and getting unknown and unwanted results.

       An example showing several commands and the use of  Return  follows:  >
       2:ino; 0:dir?d

       or > 2:ino; 0:db:block?d

       The  two	 examples  are	synonymous  for getting to the first directory
       entry of the root of the file system.  Once there,  subsequent  use  of
       the Return key ( or +, -) advances to subsequent entries. The following
       display is again synonymous: > 2:inode; :ls /

       or > :ls /

       displays 2010 in decimal (use of	 fsdb  as  a  calculator  for  complex
       arithmetic).   displays	i-number  386  in  an  inode  format. This now
       becomes the current inode.  changes the	link  count  for  the  current
       inode  to  4.   increments  the link count by 1.	 displays the creation
       time as a hexadecimal long.  displays the  modification	time  in  time
       format.	displays, in ASCII, block zero of the file associated with the
       current inode.  displays the first blocks worth	of  directory  entries
       for the root inode of this file system. It will stop prematurely if the
       eof is reached.	changes the current inode to that associated with  the
       5th  directory  entry  (numbered	 from zero) of the current inode.  The
       first logical block of the file is then displayed in  ASCII.   displays
       the  superblock	of this file system.  displays cylinder group informa‐
       tion and summary for cylinder group 1.  changes the  i-number  for  the
       seventh	directory  slot	 in the root directory to 3.  changes the name
       field in the directory slot to name.  displays the third block  of  the
       current inode as directory entries.  gets fragment 3c3 and fill 20 type
       elements with 0x20.  sets the contents of address 2050  to  0xffffffff.
       0xffffffff  may be truncated depending on the current type.  places the
       ASCII for the string at 1c92434.

       The symbols recognized by fsdb are: update the value of dot by the cur‐
       rent  value  of	type  and  display  using  the current value of count.
       numeric expressions may be composed of +, -, *, and % operators (evalu‐
       ated left to right) and may use parentheses.  Once evaluated, the value
       of dot is updated.  count indicator.  The global value of count will be
       updated	to  count.  The	 value of count remains until a new command is
       run. A count specifier of '*' will attempt to show the information of a
       block.  The  default  for count is 1.  display in structured style with
       format specifier f.  display in unstructured style with	format	speci‐
       fier  f.	  the value of dot.  increment the value of dot by the expres‐
       sion e. The amount actually incremented is dependent  on	 the  size  of
       type: dot = dot + e * sizeof (type)

	      The  default  for	 e  is	1.   decrement the value of dot by the
	      expression e (see +).  multiply the value of dot by the  expres‐
	      sion  e.	 Multiplication	 and division do not use type.	In the
	      above calculation of dot, consider the size of (type) to	be  1.
	      divide the value of dot by the expression e (see *).  restore an
	      address saved in register name.  name must be a single letter or
	      digit.  save an address in register name.	 name must be a single
	      letter or digit.	display indicator. If f is a legitimate format
	      specifier, then the value of dot is displayed using format spec‐
	      ifier f. Otherwise, assignment is assumed.   assignment  indica‐
	      tor.   The address pointed to by dot has its contents changed to
	      the value of the expression e or to the ASCII representation  of
	      the  quoted  ("  ")  string  s.  This may be useful for changing
	      directory names or ASCII file information.  incremental  assign‐
	      ment. The address pointed to by dot has its contents incremented
	      by expression e.	decremental assignment. The address pointed to
	      by dot has its contents decremented by expression e.

       A  command  must be prefixed by a ':' character. Only enough letters of
       the command to uniquely distinguish it are  needed.  Multiple  commands
       may be entered on one line by separating them by a space, tab or ';'.

       In  order  to view a potentially unmounted disk in a reasonable manner,
       fsdb offers the cd, pwd, ls, and find commands.	The  functionality  of
       these  commands	substantially  matches those of its UNIX counterparts.
       The '*', '?', and '[-]' wild card characters are available.  display or
       set  base.   As	stated	above, all input and output is governed by the
       current base. If the '=b' is left off, the current base	is  displayed.
       Otherwise,  the current base is set to b. Note that this is interpreted
       using the old value of base, so to  ensure  correctness	use  the  '0',
       '0t',  or  '0x'	prefix when changing the base. The default for base is
       hexadecimal.  convert the value of dot to a block address.  change  the
       current	directory  to  directory dir.  The current values of inode and
       dot are also updated. If no dir is specified, then  change  directories
       to  inode  2  ("/").  convert the value of dot to a cylinder group.  If
       the current inode is a directory, then the value of dot is converted to
       a  directory  slot  offset in that directory and dot now points to this
       entry.  the value of dot is taken as a relative block  count  from  the
       beginning of the file. The value of dot is updated to the first byte of
       this block.  find files by name or i-number.  find recursively searches
       directory dir and below for filenames whose i-number matches i or whose
       name matches pattern n.	Note that only one of the two  options	(-name
       or  -inum)  may	be used at one time. Also, the -print is not needed or
       accepted.  fill an area of disk with pattern p.	The area  of  disk  is
       delimited  by  dot  and	count.	convert the value of dot to a fragment
       address. The only difference between the fragment command and the block
       command	is the amount that is able to be displayed.  convert the value
       of dot to an inode address. If successful, the current value  of	 inode
       will  be	 updated  as well as the value of dot.	As a convenient short‐
       hand, if ':inode' appears at the beginning of the line,	the  value  of
       dot  is	set  to the current inode and that inode is displayed in inode
       format.	list directories or files. If no file is specified,  the  cur‐
       rent  directory	is  assumed. Either or both of the options may be used
       (but, if used, must be specified before the filename specifiers). Also,
       as  stated above, wild card characters are available and multiple argu‐
       ments may be given.  The long listing shows only the i-number  and  the
       name;  use the inode command with '?i' to get more information.	toggle
       the value of override. Some error conditions may be overridden if over‐
       ride is toggled on.  change the fsdb prompt to p.  p must be surrounded
       by (")s.	 display the current working directory.	 quit fsdb.  the value
       of  dot	is  taken as a cylinder group number and then converted to the
       address of the superblock in that cylinder group. As a shorthand, ':sb'
       at  the beginning of a line will set the value of dot to the superblock
       and display it in superblock format.  escape to shell

   Inode Commands
       In addition to the above commands, there are several commands that deal
       with inode fields and operate directly on the current inode (they still
       require the ':'). They may be used to more easily display or change the
       particular fields.

       The  value  of  dot  is only used by the ':db' and ':db' commands. Upon
       completion of the command, the value of dot is changed to point to that
       particular field. For example, >:ln=+1

       would  increment	 the link count of the current inode and set the value
       of dot to the address of the link count	field.	 access	 time.	 block
       size.   creation	 time.	use the current value of dot as a direct block
       index, where direct blocks number from 0 - 11. In order to display  the
       block itself, you need to 'pipe' this result into the block or fragment
       command.	 For example, > 1:db:block,20/X

	      would get the contents of data block field 1 from the inode  and
	      convert  it  to  a block address. 20 longs are then displayed in
	      hexadecimal (see Formatted Output section).  group id.  use  the
	      current  value  of dot as an indirect block index where indirect
	      blocks number from 0 - 2. This will only get the indirect	 block
	      itself (the block containing the pointers to the actual blocks).
	      Use the file command and start at block 12 to get to the	actual
	      blocks.	link  count.   modification time.  mode.  major device
	      number.  minor device number.  although listed here,  this  com‐
	      mand  actually operates on the directory name field. Once poised
	      at the desired directory entry (using  the  directory  command),
	      this  command  will allow you to change or display the directory
	      name. For example, > 7:dir:nm="foo"

	      will get the 7th directory entry of the current inode and change
	      its  name to foo. Note that names cannot be made larger than the
	      field is set up for. If an attempt is made, the string is	 trun‐
	      cated  to fit and a warning message to this effect is displayed.
	      file size.  user id.

   Formatted Output
       There are two styles and many format types. The two styles  are	struc‐
       tured  and  unstructured.  Structured output is used to display inodes,
       directories, superblocks and the like. Unstructured just	 displays  raw
       data.  The following table shows the different ways of displaying: For‐
       mat specifier, followed by one of: display as cylinder  groups  display
       as  inodes  display as directories display as superblocks Format speci‐
       fier, followed by one of: display as bytes display as  characters  dis‐
       play  as	 octal shorts or longs display as decimal shorts or longs dis‐
       play as hexadecimal shorts or longs

       The format specifier immediately follows the '/' or '?' character.  The
       values  displayed by '/b' and all '?' formats are displayed in the cur‐
       rent base. Also, type is appropriately updated upon completion.

       Specifies the command path

       Commands: fsck(8)


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