DEBUGFS(8)						      System Manager's Manual							DEBUGFS(8)

NAME

       debugfs - ext2 file system debugger

SYNOPSIS

       debugfs [ -b blocksize ] [ -s superblock ] [ -f cmd_file ] [ -R request ] [ -V ] [ [ -w ] [ -c ] [ -i ] [ 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.  debugfs is a debugging tool.  It has rough edges!

       -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.

       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 alloca-
	      tion 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.

       initialize 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 [-ac] [-b<block>] [-i<inode>] [-f<journal_file>] [output_file]
	      Dump the contents of the ext3 journal.

       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 des-
	      tination 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_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 con-
	      tents.

       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.

AUTHOR

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

SEE ALSO

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

E2fsprogs version 1.32						   November 2002							DEBUGFS(8)