2 .\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
3 .\" This file may be copied under the terms of the GNU Public License.
5 .TH DEBUGFS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
7 debugfs \- ext2/ext3/ext4 file system debugger
43 program is an interactive file system debugger. It can be used to
44 examine and change the state of an ext2, ext3, or ext4 file system.
47 is a block device (e.g., /dev/sdXX) or a file containing the file system.
51 Specifies that the file system should be opened in read-write mode.
52 Without this option, the file system is opened in read-only mode.
55 Disables metadata checksum verification. This should only be used if
56 you believe the metadata to be correct despite the complaints of
60 Specifies that the file system should be opened in catastrophic mode, in
61 which the inode and group bitmaps are not read initially. This can be
62 useful for filesystems with significant corruption, but because of this,
63 catastrophic mode forces the filesystem to be opened read-only.
68 represents an ext2 image file created by the
70 program. Since the ext2 image file only contains the superblock, block
71 group descriptor, block and inode allocation bitmaps, and
74 commands will not function properly.
76 no safety checks are in place, and
78 may fail in interesting ways if commands such as
80 etc. are tried without specifying the
86 is a debugging tool. It has rough edges!
88 .I -d data_source_device
91 option, specifies that
93 should be used when reading blocks not found in the ext2 image file.
94 This includes data, directory, and indirect blocks.
97 Forces the use of the given block size (in bytes) for the file system,
98 rather than detecting the correct block size automatically. (This
99 option is rarely needed; it is used primarily when the file system is
100 extremely badly damaged/corrupted.)
103 Causes the file system superblock to be read from the given block
104 number, instead of using the primary superblock (located at an offset of
105 1024 bytes from the beginning of the filesystem). If you specify the
107 option, you must also provide the blocksize of the filesystem via the
110 option is rarely needed; it is used primarily when the file system is
111 extremely badly damaged/corrupted.)
116 to read in commands from
118 and execute them. When
120 is finished executing those commands, it will exit.
125 to open the device using Direct I/O, bypassing the buffer cache. Note
126 that some Linux devices, notably device mapper as of this writing, do
127 not support Direct I/O.
132 to execute the single command
137 print the version number of
142 Before overwriting a file system block, write the old contents of the block to
143 an undo file. This undo file can be used with e2undo(8) to restore the old
144 contents of the file system should something go wrong. If the empty string is
145 passed as the undo_file argument, the undo file will be written to a file named
146 debugfs-\fIdevice\fR.e2undo in the directory specified via the
147 \fIE2FSPROGS_UNDO_DIR\fR environment variable.
149 WARNING: The undo file cannot be used to recover from a power or system crash.
155 as an argument to specify an inode (as opposed to a pathname)
156 in the filesystem which is currently opened by
160 argument may be specified in two forms. The first form is an inode
161 number surrounded by angle brackets, e.g.,
163 The second form is a pathname; if the pathname is prefixed by a forward slash
164 ('/'), then it is interpreted relative to the root of the filesystem
165 which is currently opened by
167 If not, the pathname is
168 interpreted relative to the current working directory as maintained by
170 This may be modified by using the
178 This is a list of the commands which
182 .BI blocks " filespec"
183 Print the blocks used by the inode
187 .BI bmap " [ -a ] filespec logical_block [physical_block]"
188 Print or set the physical block number corresponding to the logical block number
194 flag is specified, try to allocate a block if necessary.
196 .BI block_dump " [-f filespec] block_num"
197 Dump the filesystem block given by
199 in hex and ASCII format to the console. If the
201 option is specified, the block number is relative to the start of the given
205 Dump the contents of the inode
210 Change the current working directory to
213 .BI chroot " filespec"
214 Change the root directory to be the directory
218 Close the currently open file system. If the
220 option is specified, write out any changes to the superblock and block
221 group descriptors to all of the backup superblocks, not just to the
225 Clear the contents of the inode
228 .BI copy_inode " source_inode destination_inode"
229 Copy the contents of the inode structure in
231 and use it to overwrite the inode structure at
232 .IR destination_inode .
234 .BI dirsearch " filespec filename"
240 .BI dirty " [-clean]"
241 Mark the filesystem as dirty, so that the superblocks will be written on exit.
242 Additionally, clear the superblock's valid flag, or set it if
246 .BI dump " [-p] filespec out_file"
247 Dump the contents of the inode
253 option is given set the owner, group and permissions information on
258 .BI dump_mmp " [mmp_block]"
259 Display the multiple-mount protection (mmp) field values. If
261 is specified then verify and dump the MMP values from the given block
262 number, otherwise use the
264 field in the superblock to locate and use the existing MMP block.
266 .BI dx_hash " [-h hash_alg] [-s hash_seed] filename"
267 Calculate the directory hash of
269 The hash algorithm specified with
272 .BR legacy , " half_md4" ", or " tea .
273 The hash seed specified with
275 must be in UUID format.
277 .BI dump_extents " [-n] [-l] filespec"
278 Dump the the extent tree of the inode
284 to only display the interior nodes in the extent tree. The
288 to only display the leaf nodes in the extent tree.
290 (Please note that the length and range of blocks for the last extent in
291 an interior node is an estimate by the extents library functions, and is
292 not stored in filesystem data structures. Hence, the values displayed
293 may not necessarily by accurate and does not indicate a problem or
294 corruption in the file system.)
297 Dump unused blocks which contain non-null bytes.
299 .BI ea_get " [-f outfile]|[-xVC] [-r] filespec attr_name"
300 Retrieve the value of the extended attribute
304 and write it either to stdout or to \fIoutfile\fR.
306 .BI ea_list " filespec
307 List the extended attributes associated with the file
311 .BI ea_set " [-f infile] [-r] filespec attr_name attr_value
312 Set the value of the extended attribute
318 or read it from \fIinfile\fR.
320 .BI ea_rm " filespec attr_names...
321 Remove the extended attribute
323 from the file \fIfilespec\fR.
325 .BI expand_dir " filespec"
329 .BI fallocate " filespec start_block [end_block]
330 Allocate and map uninitialized blocks into \fIfilespec\fR between
331 logical block \fIstart_block\fR and \fIend_block\fR, inclusive. If
332 \fIend_block\fR is not supplied, this function maps until it runs out
333 of free disk blocks or the maximum file size is reached. Existing
334 mappings are left alone.
336 .BI feature " [fs_feature] [-fs_feature] ..."
337 Set or clear various filesystem features in the superblock. After setting
338 or clearing any filesystem features that were requested, print the current
339 state of the filesystem feature set.
341 .BI filefrag " [-dvr] filespec"
342 Print the number of contiguous extents in
346 is a directory and the
348 option is not specified,
350 will print the number of contiguous extents for each file in
355 print a tabular listing of the contiguous extents in the
360 to do a recursive listing of the directory.
362 .BI find_free_block " [count [goal]]"
365 free blocks, starting from
367 and allocate it. Also available as
370 .BI find_free_inode " [dir [mode]]"
371 Find a free inode and allocate it. If present,
373 specifies the inode number of the directory
374 which the inode is to be located. The second
377 specifies the permissions of the new inode. (If the directory bit is set
378 on the mode, the allocation routine will function differently.) Also
382 .BI freeb " block [count]"
383 Mark the block number
386 If the optional argument
390 blocks starting at block number
392 will be marked as not allocated.
394 .BI freefrag " [-c chunk_kb]"
395 Report free space fragmentation on the currently open file system.
398 option is specified then the filefrag command will print how many free
401 can be found in the file system. The chunk size must be a power of two
402 and be larger than the file system block size.
404 .BI freei " filespec [num]"
405 Free the inode specified by
409 is specified, also clear num-1 inodes after the specified inode.
411 .BI get_quota " quota_type id"
412 Display quota information for given quota type (user, group, or project) and ID.
415 Print a list of commands understood by
418 .BI htree_dump " filespec"
419 Dump the hash-indexed directory
421 showing its tree structure.
423 .BI icheck " block ..."
424 Print a listing of the inodes which use the one or more blocks specified
427 .BI inode_dump " filespec"
428 Print the contents of the inode data structure in hex and ASCII format.
431 Print the location of the inode data structure (in the inode table)
435 .BI init_filesys " device blocksize"
436 Create an ext2 file system on
440 Note that this does not fully initialize all of the data structures;
443 program. This is just a call to the low-level library, which sets up
444 the superblock and block descriptors.
447 Close the open journal.
449 .BI journal_open " [-c] [-v ver] [-f ext_jnl]
450 Opens the journal for reading and writing. Journal checksumming can
451 be enabled by supplying \fI-c\fR; checksum formats 2 and 3 can be
452 selected with the \fI-v\fR option. An external journal can be loaded
456 Replay all transactions in the open journal.
458 .BI journal_write " [-b blocks] [-r revoke] [-c] file
459 Write a transaction to the open journal. The list of blocks to write
460 should be supplied as a comma-separated list in \fIblocks\fR; the
461 blocks themselves should be readable from \fIfile\fR. A list of
462 blocks to revoke can be supplied as a comma-separated list in
463 \fIrevoke\fR. By default, a commit record is written at the end; the
464 \fI-c\fR switch writes an uncommitted transaction.
466 .BI kill_file " filespec"
469 and its blocks. Note that this does not remove any directory
470 entries (if any) to this inode. See the
472 command if you wish to unlink a file.
475 Change the current working directory of the
479 on the native filesystem.
481 .BI list_quota " quota_type"
482 Display quota information for given quota type (user, group, or project).
484 .BI ln " filespec dest_file"
487 which is a hard link to
489 Note this does not adjust the inode reference counts.
491 .BI logdump " [-acsOS] [-b block] [-i filespec] [-f journal_file] [output_file]"
492 Dump the contents of the ext3 journal. By default, dump the journal inode as
493 specified in the superblock. However, this can be overridden with the
495 option, which dumps the journal from the internal inode given by
497 A regular file containing journal data can be specified using the
501 option utilizes the backup information in the superblock to locate the
508 to print the contents of the journal superblock.
514 program to print the contents of all of the descriptor blocks.
519 to print all journal records that refer to the specified block.
522 option will print out the contents of all of the data blocks selected by
531 option causes logdump to display old (checkpointed) journal entries.
532 This can be used to try to track down journal problems even after the
533 journal has been replayed.
535 .BI ls " [-l] [-c] [-d] [-p] [-r] filespec"
536 Print a listing of the files in the directory
540 flag causes directory block checksums (if present) to be displayed.
543 flag will list deleted entries in the directory.
546 flag will list files using a more verbose format.
549 flag will list the files in a format which is more easily parsable by
550 scripts, as well as making it more clear when there are spaces or other
551 non-printing characters at the end of filenames.
554 flag will force the printing of the filename, even if it is encrypted.
556 .BI list_deleted_inodes " [limit]"
557 List deleted inodes, optionally limited to those deleted within
559 seconds ago. Also available as
562 This command was useful for recovering from accidental file deletions
563 for ext2 file systems. Unfortunately, it is not useful for this purpose
564 if the files were deleted using ext3 or ext4, since the inode's
565 data blocks are no longer available after the inode is released.
567 .BI modify_inode " filespec"
568 Modify the contents of the inode structure in the inode
573 .BI mkdir " filespec"
576 .BI mknod " filespec [p|[[c|b] major minor]]"
577 Create a special device file (a named pipe, character or block device).
578 If a character or block device is to be made, the
582 device numbers must be specified.
584 .BI ncheck " [-c] inode_num ..."
585 Take the requested list of inode numbers, and print a listing of pathnames
588 flag will enable checking the file type information in the directory
589 entry to make sure it matches the inode's type.
591 .BI open " [-weficD] [-b blocksize] [-d image_filename] [-s superblock] [-z undo_file] device"
592 Open a filesystem for editing. The
594 flag forces the filesystem to be opened even if there are some unknown
595 or incompatible filesystem features which would normally
596 prevent the filesystem from being opened. The
598 flag causes the filesystem to be opened in exclusive mode. The
599 .IR -b ", " -c ", " -d ", " -i ", " -s ", " -w ", and " -D
600 options behave the same as the command-line options to
603 .BI punch " filespec start_blk [end_blk]"
604 Delete the blocks in the inode ranging from
610 is omitted then this command will function as a truncate command; that
611 is, all of the blocks starting at
613 through to the end of the file will be deallocated.
615 .BI symlink " filespec target"
616 Make a symbolic link.
619 Print the current working directory.
625 .BI rdump " directory[...] destination"
630 and all its contents (including regular files, symbolic links, and other
631 directories) into the named
633 which should be an existing directory on the native filesystem.
638 If this causes the inode pointed to by
640 to have no other references, deallocate the file. This command functions
641 as the unlink() system call.
644 .BI rmdir " filespec"
648 .BI setb " block [count]"
649 Mark the block number
652 If the optional argument
656 blocks starting at block number
658 will be marked as allocated.
660 .BI set_block_group " bgnum field value"
661 Modify the block group descriptor specified by
663 so that the block group descriptor field
670 .BI set_current_time " time"
671 Set current time in seconds since Unix epoch to use when setting filesystem
674 .BI seti " filespec [num]"
677 as in use in the inode bitmap. If
679 is specified, also set num-1 inodes after the specified inode.
681 .BI set_inode_field " filespec field value"
682 Modify the inode specified by
684 so that the inode field
688 The list of valid inode fields which can be set via this command
689 can be displayed by using the command:
690 .B set_inode_field -l
694 .BI set_mmp_value " field value"
695 Modify the multiple-mount protection (MMP) data so that the MMP field
699 The list of valid MMP fields which can be set via this command
700 can be displayed by using the command:
705 .BI set_super_value " field value"
706 Set the superblock field
710 The list of valid superblock fields which can be set via this command
711 can be displayed by using the command:
712 .B set_super_value -l
716 .B show_debugfs_params
719 parameters such as information about currently opened filesystem.
721 .BI show_super_stats " [-h]"
722 List the contents of the super block and the block group descriptors. If the
724 flag is given, only print out the superblock contents. Also available as
728 Display the contents of the inode structure of the inode
731 .B supported_features
732 Display filesystem features supported by this version of
735 .BI testb " block [count]"
736 Test if the block number
738 is marked as allocated in the block bitmap.
739 If the optional argument
743 blocks starting at block number
747 .BI testi " filespec"
750 is marked as allocated in the inode bitmap.
752 .BI undel " <inode_number> [pathname]"
753 Undelete the specified inode number (which must be surrounded by angle
754 brackets) so that it and its blocks are marked in use, and optionally
755 link the recovered inode to the specified pathname. The
757 command should always be run after using the
759 command to recover deleted files.
761 Note that if you are recovering a large number of deleted files, linking
762 the inode to a directory may require the directory to be expanded, which
763 could allocate a block that had been used by one of the
764 yet-to-be-undeleted files. So it is safer to undelete all of the
765 inodes without specifying a destination pathname, and then in a separate
766 pass, use the debugfs
768 command to link the inode to the destination pathname, or use
770 to check the filesystem and link all of the recovered inodes to the
771 lost+found directory.
773 .BI unlink " pathname"
774 Remove the link specified by
776 to an inode. Note this does not adjust the inode reference counts.
778 .BI write " source_file out_file"
781 into a newly-created file in the filesystem named
784 .BI zap_block " [-f filespec] [-o offset] [-l length] [-p pattern] block_num"
785 Overwrite the block specified by
787 with zero (NUL) bytes, or if
789 is given use the byte specified by
795 is relative to the start of the file given by
801 options limit the range of bytes to zap to the specified
805 relative to the start of the block.
807 .BI zap_block " [-f filespec] [-b bit] block_num"
808 Bit-flip portions of the physical
814 is a logical block relative to the start of
816 .SH ENVIRONMENT VARIABLES
818 .B DEBUGFS_PAGER, PAGER
821 program always pipes the output of the some commands through a
822 pager program. These commands include:
823 .IR show_super_stats " (" stats ),
824 .IR list_directory " (" ls ),
825 .IR show_inode_info " (" stat ),
826 .IR list_deleted_inodes " (" lsdel ),
829 The specific pager can explicitly specified by the
831 environment variable, and if it is not set, by the
833 environment variable.
835 Note that since a pager is always used, the
837 pager is not particularly appropriate, since it clears the screen before
838 displaying the output of the command and clears the output the screen
839 when the pager is exited. Many users prefer to use the
841 pager for most purposes, which is why the
843 environment variable is available to override the more general
845 environment variable.
848 was written by Theodore Ts'o <tytso@mit.edu>.