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fsdb_ufs


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 neces-
     sary 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 rou-
     tine 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
     corresponding  block.  Note that in order to modify any por-
     tion 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  numbers  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  execu-
     tion. 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 specified 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  com-
     pleted, 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 mes-
     sage 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 parentheses. 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 command  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 depen-
                     dent 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.  Multiplication  and  division  don't use
                     type.  In the above calculation of dot, con-
                     sider 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 for-
                     mat  specifier.  then  the  value  of dot is
                     displayed using the format specifier 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  reason-
     able  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  governed  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  inter-
                                     preted 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 hexade-
                                     cimal.



     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 converted to a direc-
                                     tory  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 beginning 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 frag-
                                     ment  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 suc-
                                     cessful, 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  for-
                                     mat.



     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
                                     offset    is    within   the
                                     head/tail offsets.



     log_head                        display the header  informa-
                                     tion  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  over-
                                     ride.  Some error conditions
                                     may be overriden 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   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.



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



     !                               escape to shell



  Inode Commands
     In addition to the above commands, there  are  several  com-
     mands  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'  com-
     mands.  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 fragment com-
              mand. 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  For-
              mattedOutput.



     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 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.



     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 truncated 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  structured  and unstructured. Structured output is used
     to display inodes, directories, superblocks  and  the  like.
     Unstructured displays raw data. The following shows the dif-
     ferent 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 calculator 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 for-
     mat. 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  hexa-
     decimal 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 associated 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 prematurely 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  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:

     > 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  direc-
     tory 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  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|


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
     determining  its  availability  of  fsdb on the system. Sug-
     gested 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  flexi-
     ble clri(1M) command.










Man pages from Solaris 10 Update 8. See docs.sun.com and www.oracle.com for further documentation and Solaris information.
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