This is a list of the commands which debugfs supports.
blocksfilespec
Print the blocks used by the inode filespec to stdout.
bmap[-a]filespeclogical_block[physical_block]
Print or set the physical block number corresponding to the logical block number logical_block in
the inode filespec. If the -a flag is specified, try to allocate a block if necessary.
block_dump'[-x][-ffilespec]block_num
Dump the file system block given by block_num in hex and ASCII format to the console. If the -f
option is specified, the block number is relative to the start of the given filespec. If the -x
option is specified, the block is interpreted as an extended attribute block and printed to show
the structure of extended attribute data structures.
catfilespec
Dump the contents of the inode filespec to stdout.
cdfilespec
Change the current working directory to filespec.
chrootfilespec
Change the root directory to be the directory filespec.
close[-a]
Close the currently open file system. If the -a option is specified, write out any changes to the
superblock and block group descriptors to all of the backup superblocks, not just to the master
superblock.
clrifilespec
Clear the contents of the inode filespec.
copy_inodesource_inodedestination_inode
Copy the contents of the inode structure in source_inode and use it to overwrite the inode
structure at destination_inode.
dirsearchfilespecfilename
Search the directory filespec for filename.
dirty[-clean]
Mark the file system as dirty, so that the superblocks will be written on exit. Additionally,
clear the superblock's valid flag, or set it if -clean is specified.
dump[-p]filespecout_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_mmp[mmp_block]
Display the multiple-mount protection (mmp) field values. If mmp_block is specified then verify
and dump the MMP values from the given block number, otherwise use the s_mmp_block field in the
superblock to locate and use the existing MMP block.
dx_hash[-cv][-hhash_alg][-shash_seed]filename
Calculate the directory hash of filename. The -c option will casefold the filename before
calculating the hash. The -v option will make the dx_hash command more verbose and print the hash
algorithm and hash seed to calculate the hash. If a file system is open, use the hash_seed and
default hash_algorithm used by the file system, although these can be overridden by the -h and -s
options. The hash algorithm specified with -h may be legacy, half_md4, or tea. The hash seed
specified with -s must be in UUID format.
dump_extents[-n][-l]filespec
Dump 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 will cause dump_extents to only display 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 file system data structures.
Hence, the values displayed may not necessarily by accurate and does not indicate a problem or
corruption in the file system.)
dump_unused
Dump unused blocks which contain non-null bytes.
ea_get[-foutfile]|[-xVC][-r]filespecattr_name
Retrieve the value of the extended attribute attr_name in the file filespec and write it either to
stdout or to outfile.
ea_listfilespec
List the extended attributes associated with the file filespec to standard output.
ea_set[-finfile][-r]filespecattr_nameattr_value
Set the value of the extended attribute attr_name in the file filespec to the string value
attr_value or read it from infile.
ea_rmfilespecattr_names...
Remove the extended attribute attr_name from the file filespec.
expand_dirfilespec
Expand the directory filespec.
fallocatefilespecstart_block[end_block]
Allocate and map uninitialized blocks into filespec between logical block start_block and
end_block, inclusive. If end_block is not supplied, this function maps until it runs out of free
disk blocks or the maximum file size is reached. Existing mappings are left alone.
feature[fs_feature][-fs_feature]...
Set or clear various file system features in the superblock. After setting or clearing any file
system features that were requested, print the current state of the file system feature set.
filefrag[-dvr]filespec
Print the number of contiguous extents in filespec. If filespec is a directory and the -d option
is not specified, filefrag will print the number of contiguous extents for each file in the
directory. The -v option will cause filefrag print a tabular listing of the contiguous extents in
the file. The -r option will cause filefrag to do a recursive listing of the directory.
find_free_block[count[goal]]
Find the first count free blocks, starting from goal and allocate it. Also available as ffb.
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.) Also available as ffi.
freebblock[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.
freefrag[-cchunk_kb]
Report free space fragmentation on the currently open file system. If the -c option is specified
then the filefrag command will print how many free chunks of size chunk_kb can be found in the
file system. The chunk size must be a power of two and be larger than the file system block size.
freeifilespec[num]
Free the inode specified by filespec. If num is specified, also clear num-1 inodes after the
specified inode.
get_quotaquota_typeid
Display quota information for given quota type (user, group, or project) and ID.
help Print a list of commands understood by debugfs.
htree_dumpfilespec
Dump the hash-indexed directory filespec, showing its tree structure.
icheckblock...
Print a listing of the inodes which use the one or more blocks specified on the command line.
inode_dump[-b]|[-e]|[-x]filespec
Print the contents of the inode data structure in hex and ASCII format. The -b option causes the
command to only dump the contents of the i_blocks array. The -e option causes the command to only
dump the contents of the extra inode space, which is used to store in-line extended attributes.
The -x option causes the command to dump the extra inode space interpreted and extended
attributes. This is useful to debug corrupted inodes containing extended attributes.
imapfilespec
Print the location of the inode data structure (in the inode table) of the inode filespec.
init_filesysdeviceblocksize
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.
journal_close
Close the open journal.
journal_open[-c][-vver][-fext_jnl]
Opens the journal for reading and writing. Journal checksumming can be enabled by supplying -c;
checksum formats 2 and 3 can be selected with the -v option. An external journal can be loaded
from ext_jnl.
journal_run
Replay all transactions in the open journal.
journal_write[-bblocks][-rrevoke][-c]file
Write a transaction to the open journal. The list of blocks to write should be supplied as a
comma-separated list in blocks; the blocks themselves should be readable from file. A list of
blocks to revoke can be supplied as a comma-separated list in revoke. By default, a commit record
is written at the end; the -c switch writes an uncommitted transaction.
kill_filefilespec
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.
lcddirectory
Change the current working directory of the debugfs process to directory on the native file
system.
list_quotaquota_type
Display quota information for given quota type (user, group, or project).
lnfilespecdest_file
Create a link named dest_file which is a hard link to filespec. Note this does not adjust the
inode reference counts.
logdump[-acsOS][-bblock][-nnum_trans][-ifilespec][-fjournal_file][output_file]
Dump the contents of the ext3 journal. By default, dump the journal inode as specified in the
superblock. However, this can be overridden with the -i option, which dumps the journal from the
internal inode given by filespec. A regular 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 -S option causes logdump to print the contents of the journal superblock.
The -a option causes the logdump to print the contents of all of the descriptor blocks. The -b
option causes logdump to print all journal records that 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.
The -O option causes logdump to display old (checkpointed) journal entries. This can be used to
try to track down journal problems even after the journal has been replayed.
The -n option causes logdump to continue past a journal block which is missing a magic number.
Instead, it will stop only when the entire log is printed or after num_trans transactions.
ls[-l][-c][-d][-p][-r]filespec
Print a listing of the files in the directory filespec. The -c flag causes directory block
checksums (if present) to be displayed. The -d flag will list deleted entries in the directory.
The -l flag will list files using a more verbose format. The -p flag will list the files in a
format which is more easily parsable by scripts, as well as making it more clear when there are
spaces or other non-printing characters at the end of filenames. The -r flag will force the
printing of the filename, even if it is encrypted.
list_deleted_inodes[limit]
List deleted inodes, optionally limited to those deleted within limit seconds ago. Also available
as lsdel.
This command was useful for recovering from accidental file deletions for ext2 file systems.
Unfortunately, it is not useful for this purpose if the files were deleted using ext3 or ext4,
since the inode's data blocks are no longer available after the inode is released.
modify_inodefilespec
Modify the contents of the inode structure in the inode filespec. Also available as mi.
mkdirfilespec
Make a directory.
mknodfilespec[p|[[c|b]majorminor]]
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[-c]inode_num...
Take the requested list of inode numbers, and print a listing of pathnames to those inodes. The
-c flag will enable checking the file type information in the directory entry to make sure it
matches the inode's type.
open[-weficD][-bblocksize][-dimage_filename][-ssuperblock][-zundo_file]device
Open a file system for editing. The -f flag forces the file system to be opened even if there are
some unknown or incompatible file system features which would normally prevent the file system
from being opened. The -e flag causes the file system to be opened in exclusive mode. The -b,
-c, -d, -i, -s, -w, and -D options behave the same as the command-line options to debugfs.
orphan_inodes
List the orphan inodes in the file system.
punchfilespecstart_blk[end_blk]
Delete the blocks in the inode ranging from start_blk to end_blk. If end_blk is omitted then this
command will function as a truncate command; that is, all of the blocks starting at start_blk
through to the end of the file will be deallocated.
symlinkfilespectarget
Make a symbolic link.
pwd Print the current working directory.
quit Quit debugfsrdumpdirectory[...]destination
Recursively dump directory, or multiple directories, 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 file system.
rmpathname
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.
rmdirfilespec
Remove the directory filespec.
setbblock[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.
set_block_groupbgnumfieldvalue
Modify the block group descriptor specified by bgnum so that the block group descriptor field
field has value value. Also available as set_bg.
set_current_timetime
Set current time in seconds since Unix epoch to use when setting file system fields.
setifilespec[num]
Mark inode filespec as in use in the inode bitmap. If num is specified, also set num-1 inodes
after the specified inode.
set_inode_fieldfilespecfieldvalue
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 Also available as sif.
set_mmp_valuefieldvalue
Modify the multiple-mount protection (MMP) data so that the MMP field field has value value. The
list of valid MMP fields which can be set via this command can be displayed by using the command:
set_mmp_value-l Also available as smmp.
set_super_valuefieldvalue
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 Also available as ssv.
show_debugfs_params
Display debugfs parameters such as information about currently opened file system.
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. Also available as stats.
statfilespec
Display the contents of the inode structure of the inode filespec.
supported_features
Display file system features supported by this version of debugfs.
testbblock[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.
testifilespec
Test if the inode filespec is marked as allocated in the inode bitmap.
undel<inode_number>[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 file system and link all of the
recovered inodes to the lost+found directory.
unlinkpathname
Remove the link specified by pathname to an inode. Note this does not adjust the inode reference
counts.
writesource_fileout_file
Copy the contents of source_file into a newly-created file in the file system named out_file.
zap_block[-ffilespec][-ooffset][-llength][-ppattern]block_num
Overwrite the block specified by block_num with zero (NUL) bytes, or if -p is given use the byte
specified by pattern. If -f is given then block_num is relative to the start of the file given by
filespec. The -o and -l options limit the range of bytes to zap to the specified offset and
length relative to the start of the block.
zap_block[-ffilespec][-bbit]block_num
Bit-flip portions of the physical block_num. If -f is given, then block_num is a logical block
relative to the start of filespec.
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