Provided by: e2fsprogs_1.38-2ubuntu2_i386 bug

NAME

       debugfs - ext2/ext3 file system debugger

SYNOPSIS

       debugfs  [ -Vwci ] [ -b blocksize ] [ -s superblock ] [ -f cmd_file ] [
       -R request ] [ -d data_source_device ] [ device ]

DESCRIPTION

       The debugfs program is an interactive file system debugger. It  can  be
       used to examine and change the state of an ext2 file system.
       device  is  the special file corresponding to the device containing the
       ext2 file system (e.g /dev/hdXX).

OPTIONS

       -w     Specifies that the file system should be  opened  in  read-write
              mode.   Without  this option, the file system is opened in read-
              only mode.

       -c     Specifies that the file system should be opened in  catastrophic
              mode,  in  which  the  inode  and  group  bitmaps  are  not read
              initially.  This can be useful for filesystems with  significant
              corruption,  but  because  of this, catastrophic mode forces the
              filesystem to be opened read-only.

       -i     Specifies that device represents an ext2 image file  created  by
              the  e2image  program.   Since the ext2 image file only contains
              the  superblock,  block  group  descriptor,  block   and   inode
              allocation  bitmaps,  and the inode table, many debugfs commands
              will not function properly.  Warning: no safety  checks  are  in
              place, and debugfs may fail in interesting ways if commands such
              as  ls,  dump,   etc.   are   tried   without   specifying   the
              data_source_device  using the -d option.  debugfs is a debugging
              tool.  It has rough edges!

       -d data_source_device
              Used with  the  -i  option,  specifies  that  data_source_device
              should  be  used when reading blocks not found in the ext2 image
              file.  This includes data, directory, and indirect blocks.

       -b blocksize
              Forces the use of the given block  size  for  the  file  system,
              rather than detecting the correct block size as normal.

       -s superblock
              Causes  the  file  system  superblock  to be read from the given
              block number, rather than the default (1).  If  you  give  a  -s
              option, you must also give a -b option.

       -f cmd_file
              Causes  debugfs  to  read in commands from cmd_file, and execute
              them.  When debugfs is finished  executing  those  commands,  it
              will exit.

       -R request
              Causes  debugfs  to execute the single command request, and then
              exit.

       -V     print the version number of debugfs and exit.

SPECIFYING FILES

       Many debugfs commands take a filespec as  an  argument  to  specify  an
       inode  (as  opposed to a pathname) in the filesystem which is currently
       opened by debugfs.  The filespec  argument  may  be  specified  in  two
       forms.  The first form is an inode number surrounded by angle brackets,
       e.g., <2>.  The second form is a pathname; if the pathname is  prefixed
       by  a  forward slash (’/’), then it is interpreted relative to the root
       of the filesystem which is currently opened by debugfs.   If  not,  the
       pathname  is  interpreted  relative to the current working directory as
       maintained by debugfs.  This may  be  modified  by  using  the  debugfs
       command cd.

COMMANDS

       This is a list of the commands which debugfs supports.

       bmap filespec logical_block
              Print  the  physical  block  number corresponding to the logical
              block number logical_block in the inode filespec.

       cat filespec
              Dump the contents of the inode filespec to stdout.

       cd filespec
              Change the current working directory to filespec.

       chroot filespec
              Change the root directory to be the directory filespec.

       close  Close the currently open file system.

       clri file
              Clear the contents of the inode file.

       dump [-p] filspec out_file
              Dump the contents of the  inode  filespec  to  the  output  file
              out_file.   If  the  -p option is given set the owner, group and
              permissions information on out_file to match filespec.

       expand_dir filespec
              Expand the directory filespec.

       feature [fs_feature] [-fs_feature] ...
              Set or clear various  filesystem  features  in  the  superblock.
              After  setting  or  clearing  any  filesystem features that were
              requested, print the current state  of  the  filesystem  feature
              set.

       find_free_block [count [goal]]
              Find  the  first  count  free  blocks,  starting  from  goal and
              allocate it.

       find_free_inode [dir [mode]]
              Find a free inode and allocate it.  If  present,  dir  specifies
              the  inode  number  of  the  directory  which the inode is to be
              located.   The  second  optional  argument  mode  specifies  the
              permissions  of  the new inode.  (If the directory bit is set on
              the mode, the allocation routine will function differently.)

       freeb block [count]
              Mark the block number block as not allocated.  If  the  optional
              argument  count  is present, then count blocks starting at block
              number block will be marked as not allocated.

       freei filespec
              Free the inode specified by filespec.

       help   Print a list of commands understood by debugfs(8).

       icheck block ...
              Print a listing of the inodes which use the one or  more  blocks
              specified on the command line.

       imap filespec
              Print  the  location  of  the inode data structure (in the inode
              table) of the inode filespec.

       init_filesys device blocksize
              Create an ext2 file system on device with device size blocksize.
              Note  that  this  does  not  fully  initialize  all  of the data
              structures; to do this, use the mke2fs(8) program.  This is just
              a  call  to  the low-level library, which sets up the superblock
              and block descriptors.

       kill_file filespec
              Deallocate the inode filespec and its blocks.   Note  that  this
              does  not  remove  any directory entries (if any) to this inode.
              See the rm(1) command if you wish to unlink a file.

       lcd directory
              Change the current working directory of the debugfs  process  to
              directory on the native filesystem.

       ln filespec dest_file
              Create a link named dest_file which is a link to filespec.  Note
              this does not adjust the inode reference counts.

       logdump   [-acs]    [-b<block>]    [-i<filespec>]    [-f<journal_file>]
       [output_file]
              Dump the contents of the ext3 journal.  By default, the  journal
              inode  as  specified  in  the  superblock.  However, this can be
              overridden with the -i option, which uses an inode specifier  to
              specify  the journal to be used.  A file containing journal data
              can be specified using the -f option.   Finally, the  -s  option
              utilizes  the backup information in the superblock to locate the
              journal.

              The -a option causes the logdump program to print  the  contents
              of  all  of the descriptor blocks.  The -b option causes logdump
              to print all journal records that are  refer  to  the  specified
              block.   The -c option will print out the contents of all of the
              data blocks selected by the -a and -b options.

       ls [-l] [-d] filespec
              Print a listing of the files in the directory filespec.  The  -l
              flag  will  list files using a more verbose format.  The -d flag
              will list deleted entries in the directory.

       modify_inode filespec
              Modify  the  contents  of  the  inode  structure  in  the  inode
              filespec.

       mkdir filespec
              Make a directory.

       mknod filespec [p|[[c|b] major minor]]
              Create  a  special device file (a named pipe, character or block
              device).  If a character or block device  is  to  be  made,  the
              major and minor device numbers must be specified.

       ncheck inode_num ...
              Take the requested list of inode numbers, and print a listing of
              pathnames to those inodes.

       open [-w] [-f] [-i] [-c] [-b blocksize] [-s superblock] device
              Open  a  filesystem  for  editing.   The  -w  flag  causes   the
              filesystem  to  be  opened  for writing.  The -f flag forces the
              filesystem to be opened  even  if  there  are  some  unknown  or
              incompatible  filesystem  features  which would normally prevent
              the filesystem from being  opened.   The  -c,  -b,  -i,  and  -s
              options behave the same as those to debugfs itself.

       pwd    Print the current working directory.

       quit   Quit debugfs

       rdump directory destination
              Recursively  dump  directory  and  all  its  contents (including
              regular files, symbolic links, and other directories)  into  the
              named  destination  which should be an existing directory on the
              native filesystem.

       rm pathname
              Unlink pathname.   If  this  causes  the  inode  pointed  to  by
              pathname to have no other references, deallocate the file.  This
              command functions as the unlink() system call.

       rmdir filespec
              Remove the directory filespec.

       setb block [count]
              Mark the block number  block  as  allocated.   If  the  optional
              argument  count  is present, then count blocks starting at block
              number block will be marked as allocated.

       seti filespec
              Mark inode filespec as in use in the inode bitmap.

       set_inode_field filespec field value
              Modify the inode specified by filespec so that the  inode  field
              field has value value.  The list of valid inode fields which can
              be set via this command can be displayed by using  the  command:
              set_inode_field -l

       set_super_value field value
              Set  the  superblock  field  field  to value.  The list of valid
              superblock fields which can be  set  via  this  command  can  be
              displayed by using the command: set_super_value -l

       show_super_stats [-h]
              List  the  contents  of  the  super  block  and  the block group
              descriptors.  If the -h  flag  is  given,  only  print  out  the
              superblock contents.

       stat filespec
              Display  the  contents  of  the  inode  structure  of  the inode
              filespec.

       testb block [count]
              Test if the block number block is marked  as  allocated  in  the
              block  bitmap.   If the optional argument count is present, then
              count blocks starting at block number block will be tested.

       testi filespec
              Test if the inode filespec is marked as allocated in  the  inode
              bitmap.

       unlink pathname
              Remove  the  link  specified by pathname to an inode.  Note this
              does not adjust the inode reference counts.

       write source_file out_file
              Create a file in the filesystem named  out_file,  and  copy  the
              contents of source_file into the destination file.

ENVIRONMENT VARIABLES

       DEBUGFS_PAGER, PAGER
              The  debugfs(8)  program  always  pipes  the  output of the some
              commands through  a  pager  program.   These  commands  include:
              show_super_stats,        list_directory,        show_inode_info,
              list_deleted_inodes, and htree_dump.   The  specific  pager  can
              explicitly  specified by the DEBUGFS_PAGER environment variable,
              and if it is not set, by the PAGER environment variable.

              Note that since a pager is always used, the less(1) pager is not
              particularly  appropriate,  since  it  clears  the screen before
              displaying the output of the command and clears the  output  the
              screen  when  the pager is exited.  Many users prefer to use the
              less(1) pager for most purposes, which is why the  DEBUGFS_PAGER
              environment  variable  is available to override the more general
              PAGER environment variable.

AUTHOR

       debugfs was written by Theodore Ts’o <tytso@mit.edu>.

SEE ALSO

       dumpe2fs(8), e2fsck(8), mke2fs(8)