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fsdb_ufs(1m)

System Administration Commands                                    fsdb_ufs(1M)



NAME
       fsdb_ufs - ufs file system debugger

SYNOPSIS
       fsdb -F ufs [generic_options] [specific_options] special


DESCRIPTION
       The  fsdb_ufs  command is an interactive tool that can be used to patch
       up a damaged UFS file system. 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.


       fsdb contains several error-checking routines to verify inode and block
       addresses. These can be disabled if necessary by invoking fsdb with the
       -o option or by the use of the o command.


       fsdb reads a block at a time and will therefore work with raw  as  well
       as  block  I/O  devices.  A buffer management routine is used to retain
       commonly used blocks of data in order to reduce the number of read sys‐
       tem  calls.  All  assignment  operations  result in an immediate write-
       through of the corresponding 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.

OPTIONS
       The following option is supported:

       -o    Specify UFS file system specific options. These  options  can  be
             any  combination  of  the  following separated by commas (with no
             intervening spaces). The options available are:

             ?             Display usage


             o             Override some error conditions


             p='string'    set prompt to string


             w             open for write



USAGE
       Numbers are considered hexadecimal by default. However,  the  user  has
       control  over how data is to be displayed or accepted. The base command
       will display or set 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
       and  so  forth to a byte address. Once the address has been calculated,
       fsdb will record the result in dot (.).


       Several global values are maintained by fsdb:

           o      the current base (referred to as base),

           o      the current address (referred to as dot),

           o      the current inode (referred to as inode),

           o      the current count (referred to as count),

           o      and the current type (referred to as type).


       Most commands use the preset value of dot in their execution. For exam‐
       ple,


       > 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 a  RETURN  is  then
       typed,  the  output  routine will use the current values of dot, count,
       and type and display 400 more hex longs. A '*' will  cause  the  entire
       block to be displayed.


       End of fragment, block and file are maintained by fsdb. When displaying
       data as fragments or blocks, an error message will  be  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 would be:

         > 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, any subsequent
       RETURN (or +, -) will advance to subsequent entries. Note that

         > 2:inode; :ls
               or
         > :ls /




       is again synonymous.

   Expressions
       The symbols recognized by fsdb are:

       RETURN       update the value of dot by the current value of  type  and
                    display using the current value of count.


       #            numeric  expressions  may  be  composed  of +, -, *, and %
                    operators (evaluated left to right) and may use  parenthe‐
                    ses. Once evaluated, the value of dot is updated.


       , count      count indicator. The global value of count will be updated
                    to count. The value of count will remain until a new  com‐
                    mand is run. A count specifier of '*' will attempt to show
                    a blocks's worth of information. The default for count  is
                    1.


       ? f          display  in  structured style with format specifier f. See
                    FormattedOutput.


       / f          display in unstructured style with format specifier f  See
                    FormattedOutput.


       .            the value of dot.


       +e           increment the value of dot by the expression e. The amount
                    actually incremented is dependent on the size of type:

                    dot = dot + e * sizeof (type)

                    The default for e is 1.


       -e           decrement the value of dot by the expression e. See  +.


       *e           multiply the value of dot by the expression e. Multiplica‐
                    tion and division don't use type. In the above calculation
                    of dot, consider the sizeof(type) to be 1.


       %e           divide the value of dot by the expression e. See  *.


       < name       restore an address saved in register name. name must be  a
                    single letter or digit.


       > name       save  an  address  in register name. name must be a single
                    letter or digit.


       = f          display indicator. If f is a legitimate format  specifier.
                    then the value of dot is displayed using the format speci‐
                    fier f.  See  FormattedOutput.  Otherwise,  assignment  is
                    assumed See  =.


       = [s] [e]    assignment  indicator.  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.


       =+ e         incremental  assignment. The address pointed to by dot has
                    its contents incremented by expression e.


       =- e         decremental assignment. The address pointed to by dot  has
                    its contents decremented by expression e.


   Commands
       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.
       See individual commands for details. The '*', '?', and '[-]' wild  card
       characters are available.

       base=b

           display  or set base. As stated above, all input and output is gov‐
           erned by the current base. If the  =b is omitted, 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  cor‐
           rectness  use the '0', '0t', or '0x' prefix when changing the base.
           The default for base is hexadecimal.


       block

           convert the value of dot to a block address.


       cd dir

           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 ("/").


       cg

           convert the value of dot to a cylinder group.


       directory

           If the current inode is a directory, then the value of dot is  con‐
           verted  to  a  directory  slot offset in that directory and dot now
           points to this entry.


       file

           the value of dot is taken as a relative block count from the begin‐
           ning  of the file. The value of dot is updated to the first byte of
           this block.


       find dir [ -name n] [-inum i]

           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=p

           fill an area of disk with pattern p. The area of disk is  delimited
           by dot and count.


       fragment

           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.


       inode

           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 shorthand, 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.


       log_chk

           run  through the valid log entries without printing any information
           and verify the layout.


       log_delta

           count the number of deltas into the log, using the value of dot  as
           an  offset into the log. No checking is done to make sure that off‐
           set is within the head/tail offsets.


       log_head

           display the header information about the file system logging.  This
           shows  the  block allocation for the log and the data structures on
           the disk.


       log_otodb

           return the physical disk block number, using the value of dot as an
           offset into the log.


       log_show

           display  all deltas between  the beginning of the log (BOL) and the
           end of the log (EOL).


       ls

           [ -R ] [ -l ] pat1 pat2... list directories or files. If no file is
           specified,  the current 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 arguments may be given. The long listing
           shows  only  the  i-number and the name; use the inode command with
           '?i' to get more information.


       override

           toggle the value of override. Some error conditions may be  overri‐
           den if override is toggled on.


       prompt p

           change the fsdb prompt to p. p must be surrounded by (")s.


       pwd

           display the current working directory.


       quit

           quit fsdb.


       sb

           the  value of dot is taken as a cylinder group number and then con‐
           verted 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.


       shadow

           if the current inode is a shadow inode, then the value  of  dot  is
           set to the beginning of the shadow inode data.


       !

           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 ':ib'
       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.

       at     access time.


       bs     block size.


       ct     creation time.


       db     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 frag‐
              ment 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 FormattedOutput.


       gid    group id.


       ib     use the current value of dot as an indirect  block  index  where
              indirect  blocks number from 0 - 2. This will only get the indi‐
              rect 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.


       ln     link count.


       mt     modification time.


       md     mode.


       maj    major device number.


       min    minor device number.


       nm     although listed here, this  command  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.


       si     shadow inode.


       sz     file size.


       uid    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 displays raw  data.
       The following shows the different ways of displaying:

       ?
            c    display as cylinder groups


            i    display as inodes


            d    display as directories


            s    display as superblocks


            S    display as shadow inode data



       /
            b      display as bytes


            c      display as characters


            o O    display as octal shorts or longs


            d D    display as decimal shorts or longs


            x X    display 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 current base. Also, type is appropriately updated upon comple‐
            tion.


EXAMPLES
       Example 1 Displaying in Decimal


       The following command displays 2010 in decimal (use of fsdb as a calcu‐
       lator for complex arithmetic):


         > 2000+400%(20+20)=D



       Example 2 Displaying an i-number in Inode Format


       The  following  command  displays i-number 386 in an inode format. This
       now becomes the current inode:


         > 386:ino?i



       Example 3 Changing the Link Count


       The following command changes the link count for the current  inode  to
       4:


         > :ln=4



       Example 4 Incrementing the Link Count


       The following command increments the link count by 1:


         > :ln=+1



       Example 5 Displaying the Creation Time


       The following command displays the creation time as a hexadecimal long:


         > :ct=X



       Example 6 Displaying the Modification Time


       The following command displays the modification time in time format:


         > :mt=t



       Example 7 Displaying in ASCII


       The following command displays in ASCII, block zero of the file associ‐
       ated with the current inode:


         > 0:file/c



       Example 8 Displaying the First Block's Worth of Directorty Entries


       The following command displays the first  block's  worth  of  directory
       entries  for  the  root  inode of this file system. It will stop prema‐
       turely if the EOF is reached:


         > 2:ino,*?d



       Example 9 Displaying Changes to the Current Inode


       The following command displays changes the current inode to that  asso‐
       ciated with the 5th directory entry (numbered from zero) of the current
       inode. The first logical block of the file is then displayed in ASCII:


         > 5:dir:inode; 0:file,*/c



       Example 10 Displaying the Superblock


       The following command displays the superblock of this file system:


         > :sb



       Example 11 Displaying the Cylinder Group


       The following command displays cylinder group information  and  summary
       for cylinder group 1:


         > 1:cg?c



       Example 12 Changing the i-number


       The  following  command  changes the i-number for the seventh directory
       slot in the root directory to 3:


         > 2:inode; 7:dir=3



       Example 13 Displaying as Directory Entries


       The following command displays the third block of the current inode  as
       directory entries:


         > 2:db:block,*?d



       Example 14 Changing the Name Field


       The  following  command changes the name field in the directory slot to
       name:


         > 7:dir:nm="name"



       Example 15 Getting and Filling Elements


       The following command gets fragment 3c3 and fill 20 type elements  with
       0x20:


         > 3c3:fragment,20:fill=0x20



       Example 16 Setting the Contents of an Address


       The  following command sets the contents of address 2050 to 0xffffffff.
       0xffffffff may be truncated depending on the current type:


         > 2050=0xffff



       Example 17 Placing ASCII


       The following command places the ASCII for the string at 1c92434:


         > 1c92434="this is some text"



       Example 18 Displaying Shadow Inode Data


       The following command displays all of the  shadow  inode  data  in  the
       shadow inode associated with the root inode of this file system:


         > 2:ino:si:ino;0:shadow,*?S



ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:




       tab()   box;   cw(2.75i)  |cw(2.75i)  lw(2.75i)  |lw(2.75i)  ATTRIBUTE
       TYPEATTRIBUTE VALUE _ Availabilitysystem/core-os


SEE ALSO
       clri(1M), fsck_ufs(1M), dir_ufs(4), attributes(5), ufs(7FS)

WARNINGS
       Since fsdb reads the disk raw, extreme caution is advised in  determin‐
       ing  its  availability of fsdb on the system. Suggested permissions are
       600 and owned by bin.

NOTES
       The old command line syntax for clearing i-nodes using the ufs-specific
       '-z  i-number' option is still supported by the new debugger, though it
       is obsolete and will be removed in a future release. Use of  this  flag
       will  result in correct operation, but an error message will be printed
       warning of the impending obsolesence of this option to the command. The
       equivalent  functionality is available using the more flexible clri(1M)
       command.



SunOS 5.11                        14 Apr 2003                     fsdb_ufs(1M)
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