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    Command:

    debugfs

    
    
    

    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, ext3, or ext4 file
           system.
           device is the special file corresponding to the device  containing  the
           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  ini-
                  tially.   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 alloca-
                  tion 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,  instead of using the primary superblock (located
                  at an offset of 1024 bytes from the beginning  of  the  filesys-
                  tem).   If  you specify the -s option, you must also provide the
                  blocksize of the filesystem via the -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.
    
           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 com-
           mand 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 [-a]
                  Close the currently open file system.  If the -a option is spec-
                  ified, write out any changes to the superblock and  block  group
                  descriptors  to  all  of the backup superblocks, not just to the
                  master superblock.
    
           clri file
                  Clear the contents of the inode file.
    
           dump [-p] filespec 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.
    
           dump_extents [-n] [-l] filespec
                  Dump the the extent tree of the inode  filespec.   The  -n  flag
                  will  cause  dump_extents  to only display the interior nodes in
                  the extent tree.   The -l flag cause dump_extents to  only  dis-
                  play the leaf nodes in the extent tree.
    
                  (Please  note  that  the length and range of blocks for the last
                  extent in an interior node is an estimate by the extents library
                  functions,  and  is  not  stored  in filesystem data structures.
                  Hence, the values displayed may not necessarily by accurate  and
                  does not indicate a problem or corruption in the file system.)
    
           expand_dir filespec
                  Expand the directory filespec.
    
           feature [fs_feature] [-fs_feature] ...
                  Set  or  clear  various  filesystem  features in the superblock.
    
           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 ta-
                  ble) 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  struc-
                  tures;  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>]  [out-
           put_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
    
           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] [-e] [-f] [-i] [-c] [-b blocksize] [-s superblock] device
                  Open a filesystem for editing.  The -f flag forces the  filesys-
                  tem  to be opened even if there are some unknown or incompatible
                  filesystem features which would normally prevent the  filesystem
                  from  being  opened.   The  -e  flag causes the filesystem to be
                  opened in exclusive mode.  The -b, -c, -i, -s,  and  -w  options
                  behave the same as the command-line options to debugfs.
    
           pwd    Print the current working directory.
    
           quit   Quit debugfs
    
           rdump directory destination
                  Recursively dump directory and all its contents (including regu-
                  lar 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  path-
                  name  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 argu-
                  ment  count is present, then count blocks starting at block num-
                  ber block will be marked as allocated.
    
           set_block_group bgnum field value
                  Modify the block group descriptor specified by bgnum so that the
                  block group descriptor field field has value value.
    
           seti filespec
                  Mark inode filespec as in use in the inode bitmap.
    
           set_inode_field filespec field value
    
           stat filespec
                  Display the contents of the inode structure of the  inode  file-
                  spec.
    
           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.
    
           undel <inode num> [pathname]
                  Undelete the specified inode number (which must be surrounded by
                  angle brackets) so that it and its blocks are marked in use, and
                  optionally link the recovered inode to the  specified  pathname.
                  The  e2fsck  command  should always be run after using the undel
                  command to recover deleted files.
    
                  Note that if you are recovering a large number of deleted files,
                  linking the inode to a directory may require the directory to be
                  expanded, which could allocate a block that had been used by one
                  of  the  yet-to-be-undeleted  files.  So it is safer to undelete
                  all of the inodes without specifying a destination pathname, and
                  then  in  a  separate pass, use the debugfs link command to link
                  the inode to the destination pathname, or use  e2fsck  to  check
                  the  filesystem  and  link  all  of  the recovered inodes to the
                  lost+found directory.
    
           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  com-
                  mands   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 dis-
                  playing  the  output  of  the  command and clears the output the
                  screen when the pager is exited.  Many users prefer to  use  the
    
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